Cyclopedia of Architecture Carpentry & Building Vol IX

1

MIliiiililMli ill

Cyclopediaof

Architecture, ('arpentry,

and Build in^>:

./ General Referente Work

ON .\R( IIITECTlRi:, rAKI'KNTRY, BI'll.DINO, SrpKKINTKMJKX( E, ( ONTRACTS,

S1'E( IKK ATIDNS, HIILUINC. LAW, STAIR-Ul I LI) ING, KSTIMATING,

MASONRY, RELNKORCEI) rONfRETE, STRlCTfRAL ESGINEER-

INC, AR( IIITECTIRAL I)KA\VIN(;, SHEET METAL

WiiKK, 1IE\TIN(;, VENTILATLSt;, ETC

PreparfJ hy a Staff of

ARCHITECTS, miLDERS, EXCilNEERS, AND EXPERTS OF THE IIKWIEST

l'K< iFESSIONAL STANUINO

/ with ox<er 'Ihrte 'Ihouiond hnj^nwingt

TKN VOL IMKS

( lllt:A(io

ami:ki(\\ ri-.ciiM(m. ><)c:i:tv

I'm:

Copyright. 1907. 1909. 1912

BY

AMERICAN SCHOOL OF CORRESPONDEN'CE

Copyright. 1907. 1909. 1912

BV

AMERICAN TECHNICAL SOCIETY

Entered at Stationers' Hall. London

All Rights Reserved

Authors and Collaborators

JAMES C. PLANTSuperintendent of Computintr DivUion. OfUcp of SupcrviHini; Architx-ct. Treaj-ury,

Wushintfton. D. C.

WALTER LOULNG WEBB, C. E.

Con.sultinfT Civil EnKintvrAuthor of "KailruucJ Construction," 'Economics of Railroatl Construction," etc.

J. K. COOLIDGE, Jr., A. M.

Architect. Boston

President. Iloston Society of Architects

ActinK Director, Mu.scum of Fine Arts, Boston

H. V. vo.N HOLST, A. B., S. B.

Architect, Chicago

President, Chicaso Architectural Club

FRED T. HODGSONArchitect and Editor

Member, Ontario Association of Architects

Author of "Modern Carpentry." "Architectural Drawinar, 5>elf-Taught," "The Steel

Square," "Modem Estimator." etc.

GLENN M. HOBBS. Ph. D.

Secretary. American School of Corresiondcnce

FRANK O. DUFOUR, C. E.

Assistant Professor of Structural EnKineerinit. University of Illinoi*

American Society of Civil Ensineers

SIDNEY T. STRICKLAND. S. B.

Masnachuiietts Institute of Terhnoloiry

tkiAa Am Beaux Arts. Paris

WM. II. LAWRENCE. S. B.

i'rufraxir iif Arrhltortural Knidnerrini:. Mawiarhuned* Institute of Twhnolovy

Authors and Collaborators—Continued

EDWARD NICHOLSArchitect, Boston

^«

H. W. GARDNER, S. B.

Associate Professor of Architecture, Massachusetts Institute of TechnoloEy

JESSIE M. SHEPHERD, A. B.

Associate Editor, Textbook Department, American School of Correspondence

GEORGE C. SHAAD, E. E.

Professor of Electrical Engineering, University of Kansas

MORRIS WILLIAMSWriter and Expert on Carpentry and Building

V»

HERBERT E. EVERETTProfessor of the History of Art, University of Pennsylvania

VERNEST L. WALLACE, B. S.

Assistant Examiner, United States Patent Office. Washington. D. C.

Formerly Instructor in Electrical Engineering, American School of Correspondence

VOTIS W. RICHARDSON, LL. B.

Of the Boston Bar

WM. G. SNOW, S. B.

steam Heating Specialist

Author of "Furnace Heating." Joint Author of "Ventilation of Buildings"

American Society of Mechanical Engineers

W. HERBERT GIBSON, B. S., C. E.

Civil Engineer and Designer of Reinforced Concrete

ELIOT N. JONES, LL. B.

Of the Boston Bar

Author) and Cullaburuturs—Continued

R. T. MILLER. Jr., A. M., LL. B.

I'rt-sident. Aiiu-rican School i>{ Corrmponijenct^

WM. NEUBECKERliMtructor, Sheet Metal Department of New York Trade School

WM. BEALL GKAVSanitary EnKint-er

Member, National Asthxriation of Master Plumbers

EDWARD MAURER. B. C. E.

rroffs.sor of Mechanics, University of Wisconsin

EDWARD A. TUCKER, S. B.

Architectural Enjrineer

Member. American Society of Civil EnKineers

EDWARD B. WAITEHead of Instruction Department, American School of CorrespondenceAmerican Six'iety of Mechanicul EnKineers

Western Society of EnKineers

ALVAH HORTON SABIN, M. S.

Lecturer in New York Univor«ily

Author of "Technoloify of I'liint and Varnish." etc,

American Society of Mechanical Engineers

GEORGE R. METCALFE, M. E.

^Alitor, American Institute cif Electrical Enifim-i-rs

Formerly Hcud. Technical i'ublication Departtiient. WestinKhousa Electric & Manufac-

turlHK Co.

HENRY M. HYDEEditor

"Technical World Magazine"

CHAS. L. HL'BBARD, S. B.. M. E.

Conniilllnir Knirineer on lleatinu. Vi'ntllntlnff. I.lithtinii. ami I'owrr

Kormrrly with .S. Homer Wmaltirlilun Co.

Authors and Collaborators—Continued

FRANK CHOUTEAU BROWNArchitect, Boston

Author of"Letters and Lettering'

DAVID A. GREGGTeacher and Lecturer in Pen and Ink Rendering, Massachusetts Institute of Technology

CHAS. B. BALLChief Sanitary Inspector, City of ChicagoAmerican Society of Civil Engineers

ERVIN KENISON, S. B.

Assistant Professor of Mechanical Drawing, Massachusetts Institute of Technology

CHAS. E. KNOX, E. E.

Consulting Electrical EngineerAmerican Institute of Electrical Engineers

JOHN H. JALLINGSMechanical Engineer

FRANK A. BOURNE, S. M., A. A. I. A.

Architect, Boston

Special Librarian, Department of Fine Arts, Public Library Boston

ALFRED S. JOHNSON, Ph. D.

Formerly Editor "Technical World Magazine"

GILBERT TOWNSEND, S. B.

With Ross & McFarlane, Montreal

HARRIS C. TROW, S. B., Managing Editor

Editor-in-Chief, Textbook Department. American School of Correspondence

Authorities Consulted

THEeditors have freely consulted the standard technical literature

of America and Europe in the preparation of these volumes. Theydesire to exjjress their indebtedness jjarticularly to the f(j|lowing

eminent authorities whose well-known works should be in the library of

everyone connected with buildinjr.

Grateful acknowledgment is here made also for the invaluable co-

operation of the foremost architects, engineers, and builders in makingthese volumes thoroughly re|)resentative of the very best and latest prac-tice m the design and construction of buildings; also for the valuable

drawings and data, suggestions, criticisms, and other courtesies.

J. B. JOHNSON, C. E.

Formerly Dean, CoIIckc of Mechanics and Enfrineerinir. University of WisconsinAuthor of "Enirinoorintr Contracts and Siiecifications," "Materials of Construction,"

Joint Author of "Theory and Practice ;in the Desitrnini? of Modern Framed Struc-

tures"

V»

JOHN CASSAN WAIT, M, C, E., LL. B.

Counselor-at-Law iind ConsultinR Entrinecr: Formerly Assistant Professor of Enicineer-

injt at Harvanl UniversityAuthor of "EnKinecrinK and Architectural Jurisprudence"

T. M. CLARKFVIlow of the American Institute of Architects

Author of "Buildinir Superintendence." "Architect. Builder, ami Owner before the

Law"

FRANK E, KIDDER. C, E.. Ph. I).

Consultinic Architect and Structural Knicincer; Kellow of the American Institute of

Architocta

Author of "Architects' and Builders' Pocket- Pook :

""Ruildinir Construction and

Superintendence: Part I. Masons' Wtirk : Part II. CariH-ntem' Work: Part 111.

Truued lUxjfs and Koof Trunscs;" "Churches and Chapeln"

V*

AUSTIN T. BYRNE, C. K.

Civil Knsinii'r

Author of "Inspection of MaU'rIals and Workmanship Employed In Conslruclkm."

"Ilitfhway Construrtlon"

"y

VV. R. WAREForm«'rly PriifiM««or of Arrhltrvture, Columbia UniversityAuthor of "Mi<lrrn l'rni|>eclivo"

Authorities Consulted—Continued

CLARENCE A. MARTINProfessor of Architecture at Cornell University

Author of "Details of Building Construction"

FRANK N. SNYDERArchitect

Author of "Building Details"

^*

CHARLES H. SNOWAuthor of "The Principal Species of Wood, Their Characteristic Properties"

*>*

OWEN B. MAGINNISAuthor of "How to Frame a House, or House and Roof Framing

'

^•

HALBERT P. GILLETTE, C. E.

Author of "Handbook of Cost Data for Contractors and Engineers"

^«

OLIVER COLEMANAuthor of "Successful Houses"

^«

CHAS. E. GREENE, A. M., C. E.

Formerly Professor of Civil Engineering, University of MichiganAuthor of "Structural Mechanics"

LOUIS de C. BERGAuthor of "Safe Building"

^*

GAETANO LANZA, S. B., C. & M. E.

Professor of Theoretical and Applied Mechanics. Massachusetts Institute of TechnologyAuthor of "Applied Mechanics"

IRA 0. BAKERProfessor of Civil Engineering, University of Illinois

Author of "A Treatise on Masonry Construction"

GEORGE P. MERRILLAuthor of "Stones for Building and Decoration"

FREDERICK W.TAYLOR, M. E., andSANFORD E.THOMPSON, S. B., C.E.

Joint Authors of "A Treatise on Concrete, Plain and Reinforced"

A. W. BUEL and C. S. 1111.L

Joint Authoni of"Reinforced Concrete"

NEWTON HARRISON, E. E.

Author of Klectric Wirinir. DiaKrama anJ Switchboard*"

•V

FRANCIS B. CROCKER. E. M.. Ph. D.

Head of Department of Electrical Enuinecrinir. Columbia Univemity; i i .idem.

American Institute of Klectrical Eni?ineer8

Author of "Electric LiRhtini?"

VJ. K. CKAVATH and V. K. LANSINGH

Joint Authors of"Practical Illumination"

JOSEPH KENDALL FREITAG. B. S.. C. E.

Authom of"Architectural Enitincorink'."

"Fireproofinif of Steel BuildinKs"

WILLIAM 11. BIRKMIRE, C. E.

Author of"IManninj: and Construction of Hiith Office BuildinRs." "Architeotural Iron

and Steel, and Ita Application in the Construction of Buildings." "Compound

Riveted Girders," "Skeleton Structures." etc.

EVERETT U. CROSBY and HENRY A. FISKE

Joint Authors of"Handbook of Fire Protection for Improved Risk"

CARNEGIE STEEL COMPANYAuthor* of "Pocket Companion. ContaininK Useful Information and Tables Appertain-

InK to the lIiMS of Steel"

J. C. TKAUTWINE, C. E.

Author of "Civil Kniclncer'a Pockct-Hook"

"y

ALPHA PlKia'E .lAMLSON, M. K.

Aiiolitunt PrufesHor ..f Mi-ctmnliiil Driiwrnn. Purdue l'nlver»ltjr

Autliiir of "Advnnoi-d Merlmnlcnl Drawinit"

V»

FRANK CHOUTEAU BliOVVN

Arrlillrct ikinlnn

Aiithiir of"

t.<>ttrr<i nnM l.«'lt<'rintt"


HENRY McGOODWINAuthor of "Architectural Shades and Shadows"

^«

VIGNOLAAuthor of "The Five Orders of Architecture," American Edition by Prof. Ware

CHAS. D. MAGINNISAuthor of "Pen Drawing, An Illustrated Treatise"

FRANZ S. MEYERProfessor in the School of Industrial Art. Karlsruhe

Author of"Handbook of Ornament," American Edition

RUSSELL STURGISAuthor of "A Dictionary of Architecture and Building,"' and "How to Judge Archi-

tecture"

A. D. F. HAMLIN, A. M.

Professor of Architecture at Columbia UniversityAuthor of "A Textbook of the History of Architecture

RALPH ADAMS CRAMArchitect

Author of "Church Building'

C. H. MOOREAuthor of

"Development and Character of Gothic Architecture"

ROLLA C. CARPENTER, C. E., M. M. E.

Professor of Experimental Engineering, Cornell UniversityAuthor of "Heating and Ventilating Buildings"

WILLIAM PAUL GERHARDAuthor of "A Guide to Sanitary House Inspection"

^»

I. J. COSGROVEAuthor of "Principles and Practice of Plumbing"

COriSTRUCTION DRAWIHasnov/iriG.

aHUET i^ETAL mUTi. AND VEMTILATOR. IN

VEriTILATIOM WORK.

'Bz.sndJIron Br>a-C€>

Jomtbefwcen Vent.

<

—r^

Vent.

-iboir

-^M^

JL

',Wood'^

a«.rjd.

Secfton&Jl view s'ho\A/l"n^ ventilaJtion

pipes conrjcclfed To drum in aJlic

e>s.lso sTea^m coils in drum To

crcavte sucTion.

Foreword

HF^ nii)i(l I'volutiuii (if constructive methods in recent

.\t':iis. as illustrated in tlif use of steel and concrete,

'^ ^f 1^^' '^'"^ ^'"' i'l^-'i't-'Ji^wl size and complexity of buildinjfs,

~has created the necessity foi' an antliority wliiih shall

embody accumulated experience and ai)proved practice along a

variety of corrt'lated lines. Tin' Cyclope(lia of Architecture,

Carpentry, and Huildiiiir is designed to lill this acknowledged

need.

C, There is no indiiNirv (hut coinpares with Building in the

close interdeiwndence of its subsidiaiy trades. The Architect,

for example, who knows nothing of Steel oi- Concrete con-

struction is today a> niurh out of iilace on important work

as the Contractor who cannot make intelligent estimato,s, or who

understands nothing of hi-^ legal right-; and responsibilities. A

carpenter must now know s«»nn'thing of Nhisoiuy, FJeeliie Wiring,

and. in fact, all othei' trades employed in the erection of a l)uild-

ing; and the same is tiue <yi' all the craftsmen whose handiwork

will enter into tlie completed structure.

C. Neither pains noi- expen-^e have lieen spared to make the

pro.sent work the most eimipreliensive and authoritative on the

Hul)ject of Building and its allied industries. The aim has Immmi.

not merel\- to create a work which will a|>peal lo llie trained

expert, but one that will commend itself also to the beginner

and the self-taught, practical man by giving him a working

knowledge of the principles and methods, not only of his own

particular trade, but of all other branches of the Building Indus-

try as well. The various sections have been prepared especially

for home study, each written by an acknowledged authority on

the subject. The arrangement of matter is such as to carry the

student forward by easy stages. Series of review questions are

inserted in each volume, enabling the reader to test his knowl-

edge and make it a permanent possession. The illustrations have

been selected with unusual care to elucidate the text.

C, The work will be found to cover many important topics on

which little information has heretofore been available. This is

especially apparent in such sections as those on Steel, Concrete,

and Reinforced Concrete Construction; Building Superintendence ;

Estimating; Contracts and Specifications, including the princi-

ples and methods of awarding and executing Government con-

tracts; and Building Law.

€, The Cyclopedia is a compilation of many of the most valu-

able Instruction Papers of the American School of Correspond-

ence, and the method adopted in its preparation is that which this

School has developed and employed so successfully for many years.

This method is not an experiment, but has stood the severest of all

tests—that of practical use— which has demonstrated it to be the

best yet devised for the education of the busy working man.

C In conclusion, grateful acknowledgment is due the staff of

authors and collaborators, without whose hearty co-operation

this work would have been impossible.

Tabic of Contents

Vttl.rMK IX

Electric Wiring .. . By Charles E. Knoxf Pa^e •!!

Wired Run in Conduitu: in MoMinit — Knob and Tube Wirinit — Wire* Exposed

on In»ulator« — Mi-lal Conduit — Armored Conduit — Armort-d Cable— Fibroun

Tubing — Two- Win- and Thrco-Win- .SyHti-ma- SizeH of Comluctom — FormulajJ

for CalcuUitini; I-oiw. Current, etc. — In.sUillation — Location of Outlets — Chaac*

for Feeders and Mains - Ix>cation of Cutout Cabinets and Distributint: Centers

Testintr -Alternatinir-Currcnt Circuita-Drop in A. C. Line*—Wirinsr an Ofllce

Buildintt— Outlet-Boxes— nuBhintc«— FuRC-Boxcs—Cutout Panels Fuse-Links

—Cartridge Fuse.s— Electric Bell Wiring

Electric LightiN(; . . . . B>j G. r. Shaad Page 95

Historical Sketch — Incandescent Lamps — Manufacture — Carbon Filament-

Voltage and Candlepower — Efficiency — Selection — Distribution of Light —Metallic-Filament Ijimps — Tantalum Lamp— Tungsten Lamp—Osmium Lamp— Helion Lamp — Nernst Lamp — Mercur>'-Vapor Lamp — Moore-Tube Light-

Arc Lamps— Arc-Lamp Mechanisms — Flaming-Arc Lamp — Power Distribu-

tion Illumination — Residence Lighting — Lighting of Public Halls and Offices

— Table of Lighting Data

Skylights, Roofing, Cornice Work . By William Neubecker Page 163

Skylight Bars — Condensation Gutters— Reinforcing Strips— Weight of Glass—

Single-Pitch and Double-Pitch Skylights—Hip Monitor Skylight—Ventilation-

Flat Extension Skylight — MeUl Roofs — Roof Mensuration — Corrugate<l Iron

Roofing ami Siding — Members of Cornice — Brackets. Tnis.sos — Raking Mold-

ings — Miter Cutting — Development of Blanks for Curved Moldings

Plastering . ... By Frank Chouteau Brown Page 297

Interior Plaatering—Lathing—Plaster Materials-Slaking and Working Lime—

MorUr— Rough Plaster Finish — Patent Plasters — Back Plastering — Plaster

Cracks — Drying PlasU'r — Plaster Molding — Exterior Plastering

Painting By .\. H. Sabiu I'ajro ;!2'.>

Data of Ctmi — Crcoaoting — Priming Coat — Paintii—Oil Finish — Linseetl Oil —

Mixing and Grinding—Thinners and Dryers—White Ix?ad—White Zinc—Adulter-

nls—Tinting Colors— Brushes — Fillers — House Painting — Painting Plastered

Walls- Repainting — R.">f Painting — Painting Structural Metal — Varnish-

Shellac - Damar - Enamel Paints - Floor Finishing -Glaxing

Index .... Page 363

• For page numlicrs. "«> foot of pau<i<.

» For profesaional standing of authors. «' li'-l of Aiilhiirs ami Collaborator* at

front of volume.

ELECTRICAL KITCHEN IN EDISON BUILDING, CHICAGO

ELECTRIC WIRING

.mi:th()I)s oi wikiNO

T\\v (litlVn-iit iiiftlKMls of \\iriii<; wliicli an- ikavaj>pn>\(.*(l l»y tlie

National Hoanl of Firt- I'mk'nvriters, may In- tlassiliwi uiultT four

i^fiienil lieails, as follows:

1. WiHEs Run' Concealed in Conduits.

2. WiuES Run in Moulding.

3. Concealed Knou a.nd Tube Wikino.

4. Wires Run Exposed on Insulators.

WIRHS I-JIN CONCnALED IN CONDIITS

Under this general heail, will Ik- included tiie following:

(o) Wires run in rigid conduits.

(6) Wires run in flexible metal conduits.

(r) Armoreil cable.

Wires Run in Rigid Conduit. The form of rigid metal conduit now

use<l almost t-xcliisixi-ly,

(•oii>i>i> of plain irongasj)ij)e the interior sur-

face of which has Ik-cii j)rej)are<l liy removing the scale and hy remov-

ing the irregidarities,and which is then coate<l with lle\il)le enamel.

The outside of the pi|>e is given a thin coat (»f enamel in some eases,

and, in o t h c r

cases, is galvan-

ized. Fig. 1

shows one make, 11/ ' '^-^ '• KIkI'I Hiiainrlr.l I'lMiilult. riiHif

Ot enamele«l (Un- CourU$y of American Conduit Mfg. Co., PUtttmrg, l\t.

lined I conduit.

.\iiother form of rigid conduit is that known as the armortd con-

duit, which consists of ironjiijM-

with an interior lining of pajHT

impregnate*! with asphaltum or ..imilar compound. 'This latter form

of conduit is now rapiillv going out of us*-, owing to the uidinctll»ilH*

iK-ingclu-aprr ami la^icr to install, and owing also to imj)nive«l mellxNls

of pn)tccting the iron pipe frnm corrosion, and to the intniduclion of

additioiuil hniid on tin- lonductors, which |«irtly <-om|H'n.sates ft>r the

11

ELECTRIC WIRING

pipe being unlined. Trie introduction of improved devices—such as

outlet insulators, for protecting the conductors from the sharp edges of

the pipe, at outlets, cui-out cabinets, etc.—also decreases the neces-

sity of the additional protection afforded by the interior paper lining.

Rigid Conduits are made in gaspipe sizes, from one-half inch to

three inches in diameter. The following table gives the various data

relating to rigid, enameled (unlined) conduit:

TABLE I

Rigid, Enameled Conduit—Sizes, Dimensions, Etc.

ELECTHIC WIUIN'G

TABLi: III

Two Wires in Une Conduit

Sizr. WiHK. U &. 8 U.

ELECTRIC WIRING

using these tables, for the reason that the sizes of conductors which

may be safely installed in any run of conduit depend, of course, uponthe length of and the number of bends in the run. The tables are

based on average conditions where the run does not exceed 90 to 100

feet, without more than three or four bends, in the case of the smaller

sizes of wires for a given size of conduit; and where the run does not

exceed 40 to 50 feet, with not more than one or two bends, in the case

of the larger sizes of wires, for the same sizes of conduit.

Unlined conduit can be bent without injury to the conduit, if the

conduit is properly made and if proper means are used in making the

bends. Care should be exercised to avoid flattening the tube as a result

of making the bend over a sharp curve or angle.

In installing iron conduits, the conduits should cross sleepers or

beams at right angles, so as to reduce the amount of cutting of the

beams or sleepers to a minimum.

Where a number of conduits originate at a center of distribution,

they should be run at right angles for a distance of two or three feet

from the cut-out box, in order to obtain a symmetrical and workman-

like arrangement of the conduits, and so as to have them enter the

cabinet in a neat manner. "\\Tiile it is usual to use red or white lead

at the joints of conduits in order to make them water-tight, this is

frequently unnecessary in the case of enameled conduit, as there is

often sufficient enamel on the thread to make a water-tight joint.

When iron conduits are installed in ash concrete, in Keene

cement, or, in general, where they are subject in any way to corrosive

action, they should be coated with asphaltum or other similar protec-

tive paint to prevent such action.

While the cost of circuit work run in iron conduits is usually

greater than any other method of wiring, it is the most permanentand durable, and is strongly recommended where the first cost is not

the sole consideration. This method of wiring should always be

used in fireproof buildings, and also in the better class of frame build-

ings. It is also to be recommended for exposed work where the work

is liable to disturbance or mechanical damage.Wires Run in Flexible Metal Conduit. This form of conduit,

shown in Fig. 2, is described by the manufacturers as a conduit com-

posed of "concave and convex metal strips wound spirally upon each

other in such a manner as to interlock several concave surfaces and

14

ELKCTHIC W111IN(]

Fig. 2. Flexible Sl.'clC.udult.

Vourtt*!/ of Sterling Electric Co., Trot/. X. V-

prtvstMittheir convex surfaces, lx)th exterior aiui interior, thereby

securing a smooth and cijniparatively frictionless surface inside and

out.

The fielil fur thr iim- i.l" this form of conduit is rapidly increasing.

Owing to its llexil)ility, coiKhiit df this fy|M' <;iii Ik- ns«il in nuniemus

cases where the

rigid conduitcould not possi-

1) 1 y be e m -

ployed. Its use

is to be recom-

mendeil al)Ove

all the other forms of wiring, except that installe<l in rigid conduits.

For new fireproof buildings, it is not so durable as the rigid conduit,

Ix'cause not so water-tight; and it is ver}' difliciilt, if not impossible,

tool)tain as workmanlike a condu't system with tiie flexible as with the

rigid type of conduit. For completed or old frame luiildings, liowever,

the use of the flexible conduit is sujoerior to all other forms of wiring.

Tal)le V gives the inside diameter of various sizes of flexible cx)n-

duit, and the lengths of tandard coils. inside diameter of this

conduit is the same as that of the rigid conduit; and the table given

for the maximum sizes of conductors which may l)e installiHl in the

various sizes of conduits, maybe usetl also for flexible steel conduits,

except that a little more margin should Ix; allowe<l for flexible steel

conduits than for the rigid conduits, as the stiffness of the latter makes

it jK>ssil)leto pull in slightly larger sized contluctors.

TABLE VOrcenfield I-Icxiblc Steel Conduit

Is.HIL'l.

6 ELECTRIC WIRING

This conduit should, of course, be first installed without the con-

ductors, in the same manner as the rigid conduit. Owing to the

flexibility of this conduit, however, it is absolutely essential to fasten

it securely at all elbows, bends, or offsets; for, if this is not done, con-

siderable difficulty will be ex-

perienced in drawing the con-

ductors in the conduit.

The rules governing the in-

stallation of this conduit are

the same as those covering

rigid conduits. Double-braided

Fig. 3. Use of Elbow Clamp for Fastening Flex- Conductors are required, andIble Conduit in Place. ,, i •, i iii i i

the conduit should be grounded

as required by the Code Rules. As already stated, the conduit should

be securely fastened (in not less than three places) at all elbows; or

else the special elbow clamp made for this purpose, shown in Fig. 3,

.should be used.

In order to cut flexible steel conduit properly, a fine hack saw

should be employed. Outlet-boxes are required at all outlets, as well

as bushing and wires to rigid

conduit. Fig. 4 shows

of flexible steel conduit

5, 6, and 7 show, respectively,

an outlet box and cover, outlet

plate, and bushing used for this

conduit.

Armored Cable. Thereare many cases where it is im-

possible to install a conduit

system. In such cases, prob-

bably the next best results maybe obtained by the use of steel

armored cable. The rules gov-

erning the installation of annored cable are given in the Natimial

Electric Code, under Section 24-A, and Section 48; also in 24-S. This

cable is shown in Fig. 8.

Steel armored cable is made by winding formed steel strips over

the insulated conductors. The steel strips are similar to those used

coil

Figs.

Fig. 4. A 100-Foot Coll ofFlexible Steel Conduit.

Courtesy of Sprague Electric Co., New Tork,N.Y.

ELECTRIC WIRING

for the steel eoiuliiit. (are is taken in forming tlie euljle, tu avoid

cnishinj; or ahraiilinij tlie insnlation on the eoiuliictors as the steel

Fig. 5. Outlet Box for Flexible Slei-1

strips are fnl and formed over the same. In tlie process of mannfae-

ture, the spools of steel ribbon are of irregnlar length, and when a

FIk'. ft. outlet IM.itf for Flexible Stt«l Flpr 7.

Co I III u 1 1. Courtftynf Spriujut 1 SnrYork, S.Y.

s|>ool is emj)ty, tin- machine isstojipi-d, ;iiid the rililum is slarletl on

the ne.xt sj)ooI, the process being eontinutxl. There is no rea.son whv

^ V y*

PlR. ft. Floxlbln AnnonM Cable. Twin PonduotonL

Courlny of Spragu* KUttrie Co., Krw York, A". 1*.

the conduit cai>lcs could not In- mndc of any length; but their aetnul

lengths as made are dctcrmiiuHl by eonvciiien e in haiulling. Ariuoa\]

17

8 ELECTRIC WIRING

cable is made in single conductors from No. 1 to No. 10 B. & S. G.;

in twin conductors, from No. 6 to No. 14 B. & S. G.; and three-conduc-

tor cable, from No. 10 to No. 14 B. & S. G. Table VI gives various

data relating to armored conductors:

TABLE VI

Armored Conductors—Types, Dimensions, Etc.

Size

KLKCTHIC WlUIXr, 9

tors) art' aniioml caljlf a«la|>tttlfor Dniiiian' iiuli>ur work. Tvjk*

HM (twill coiuluctors) is a<la|)t«'<lfor marine wiriiij;. Tvih-s DL

(sinfi;le), HXI. (twin), and HXL :{ ('i conductors) haw the conductors

lead-encase<l, with the steel armor outside, and an- e.s[)ecially adapted

for damp places, sucli as l)reweries, staljles, and similar places.

Tvpe H is use«l for tlexihUword j)cndants, and is suitable for

factories, mills, show windows, and other similar jjlaees. Tj'pe EMis the .siime as Type K; hut the flexihle conl is reinforcwl, and is suit-

able for marine work, for use in damj) places, and in all ca.ses where it

will U" subject to ver}' rouf^h handling;;.

While this form of wirinj^ has not the advantage of the conduit

svstem—namely, that the wires can U' withdrawn and new wires

mserte<l without disturbing the buildin<( in any way whatever—yet it

has many of the advantages of the flexible steel conduit, and it has

some additional advantages of its own. For example, in a building

alreadv erected, this cable can be lished between the tlinirs antl in the

partition walls, where it would l)e impossible to install either rigiil

conduit or flexible steel conduit without disturbing the floors or

walls to an extent that wouUl be objectionable.

Annore<l conductors .should be continuous from outlet to outlet,

without Iw'ing spliced and installed on the loop .system. Outlet Utxes

should be installwl at all outlets, although, where this isimi)o.s.sible,

outlet plates may be used under certain conditions. Clamps should

l.rj)ri.\

iilnl at all outlets, switch-boxes, junction-lK).xes, etc.. (o hold

the cable in place, and also to .ser\-e as a means of grounding the steel

sheathing.

Armored cable is le.ss expensive than the rigid conduit or the

flexible steel conduit, but more expensive than cleat wiring or knob

and tube wiring, and is strongly reconunenditl in preference to the

latt.T.

\\II^!:S RIN IN MOI IDINCi

Moulding is ver}' extensively used f<pr electric circuit work, in

extending circuits in buildings which have already U-en wiriNl, and

also in wiring buildings which were not pmvidetl with ele<-lric cin'uit

Work at the time of their erection. 'The n-ason for the |M)pularity «)f

niouMing is that it furnishes a convenient and fairly giKHl-Kniking

ruiuvav fur the wiri's, und protects ihem fnmi mechanical injur.'.

II)

10 ELECTRIC WIRING

Fig. 9. Two-Wire Wood MouldiuiJ

It seems almost unwise to place conductors carrying electric current,

in wood casing; but this method is still permitted by the National

Electric Code, although it is not allowed in damp places or in places

> where there is liability to damp-"^

%, —sj T I ness, such as on brick walls,

in cellars, etc.

The dangers from the use of

moulding are that if the wood

becomes soaked with water,

there will be a liability to leak-

age of current between the conductors run in the grooves of the mould-

ing,and to fire being thereby started, which may not be immediately dis-

covered. Furthermore, if the conductors are Overloaded, and conse-

quently overheated, the wood is likely to become charred and finally ig-

nited. Moreover, the moulding itself is always a temptation as affording

a good "round strip" in which to drive nails, hooks, etc. However, the

convenience and popularity of moulding cannot be denied; and until

some better substitute is found, or until its use is forbidden by the

Rules, it will continue to be used to a very great extent for running

circuits outside of the walls and on the ceilings of existing buildings.

Figs. 9, 10, 11, and 12 show two- and three-wire moulding respectively;

and Table VII gives complete data as to sizes of the moulding required

for various sizes of conductors.

While the Rules recommend the use of hardwood moulding, as a

matter of fact probably 90 per cent of the moulding used is of white-

wood or other similar cheap, soft wood . Georgia pine or oak ordinarily

S

dGO

o —Ac- -Ab- -Aa- Ab- -Ac-*CD

Fig. 10. Two-Wire Wood Moulding.

costs about twice as much as the soft wood. In designing moulding

work, if appearance is of importance, the moulding circuits shoulJ

be laid out so as to afford a symmetrical and complete design. For

20

KI.KCTKK" WIUING 11

exampli', if an initlct is U> In- locatnl in the center of the ceiling,

the inoiiltlinj,' shouM Iw continued from wall to wall, the [Mjrtion l>ey(jn«l

the outlet, of course, having no conductors inside of tiie moulding.

If four outlets are to Ih' placetl <jn the <eiling, the r-ctangle of moulding

should 1h' coinijlctJ-^lmi the fourth side, altliouj^'h, of coiirM*. no (.tm-

Kl^,'. 11. Thn-i- \Vlr«' Wood .Mi.uMuik

ductors nee«l Ik-])lace<l

in this portion of the moulding. I)«ting thi.s

increases the cost l»ut little aiul adds greatly to the appeanmce.

Moulding is fre(|nently use<l in combination with other meth(Mls

of wiring, including armored cable, flexible steel tubing, and fibrous

tubing. In many instances, it is po.ssible to fish tubing U'tween

U^ams or studs nmning in a certain direction; but when the conduc-

tors are to run in another direction or at right angles to the lK>ams or

studs, exj)osed work is nece.s.sary. In such ca.se.s, a junction-lM)x or

outlet-box nuist be placed at the point of comiection l)etweeii the

moulding and the armored cable or steel tubing.

Where circuits are nm in moulding, and pass through the floor,

additional protection must be provi(h'<l, as reciuiriHl by the ('(xlc liu}«\s,

GO—Ac Ab-

«1m

Aa— - - Ab-*— Aa --^Ab Ag-io

riK. 12. Tlir.'c'Wli-r WimmI MuuUlliifc'.

til protect the moulding. As a nilc. it is belter to use C4>nduit for all

{Mirtions of moulding within six feet of the flo«)r, .S4) as to avoid tlu-

|)ossibilitv of injurv to the «iriuits. When- a combination of in»n

conduit or flexible steel tubing is us«'»l with moulding, it is well t<t um*

double-}»raided conductors throughout, ln'<'ause. although only single-

12 ELECTRIC WIRING

TABLE Vll

Sizes of Mouldings Required for Various Sizes of Conductors

ol

Z

u.

FT-ErrUIC WIRING 13

onlinan' conditions, of the cost of annore<l c-ahle. Where tlie Litter

iiietlKxl of wiritii: or the conthiit .system can l»e einplovwj, one or tne

other of tliese two methods should Ik- used in preference to moulding,

Fig. 13 Fuseless CordRDseltf.

Courtfity of Croute- Trinrlt Co.,

Syraaue, X. 1'.

Fig. H. Device for Maklng"Tap" In

Mollldlug.

Vourttny of 11. T. Patttt Ci.,r/iil>nl<lpfiia, IM.

ns the work is not only more .suhstantial, but also siifer. Various forms

of metal mouldin<j; have been intHMJuced, Init up tt) the present time

have not met with the success which they deserve.

CONCIIALHI) KNOB ANDTl HP: W IRIN(i

This metlKHJ of wirini' is still allowed hv the Xaliimal KUctric

Cfxlf, althou;;h many vigorous attempts have l)een ma<le to have it

nlH)lishe<l. Each of these attempts lias met with the strongest

opposition from contractors and central stations, particularly in small

towns and villages, the argument for this metluHl InMiig, that it is the

chca|)est metluHl of wiring, and that if it were forbidden, many j)laivs

which are wire«l according to this iiielluHl would not 1k> winil at all,

and the use of electricity would therefore Ik.' nuich ri'strictetl, if not

entirely done away with, in such conununities. This argument, lu)W-

ever, is onlv a temponirv makeshift obstruction in the wav of inevitable

pntgress, and in a fi-w years, mwloubtnlly, the con<-eale«l knob and

tuU- mcthixl will Ik- forbidden by the Xaiinnnl EUciricCixlc.

The cost of wiring at-conling to this metluMl is aUuit one-lhinl

of the cost of circuits nm in rigid coniluit, and alniut one-half of the

cost of circuit.s run in armori-tl cable. The latter metluxl of wiring

88

14 ELECTRIC WIRING

is rapidly replacing knob and tube wiring, and justly so, wherever

the additional price for the latter method of wiring can be obtained.

As the name indicates, this method of wiring employs -porcelain knohs

Fig. 15. Knob and Tube Wiring.

and tubes, the circuit work being run concealed between the floor beams

and studs of a frame building. The knobs are used when the circuits

run parallel to the floor beams; and the porcelain tubes are used when

the circuits are run at right angles to the floor beams.

Fig. 15 shows an example of knob and tube wiring. In concealed

knob and tube wiring, the wires must be separated at least ten inches

from one another, and at least one inch from the surface wired over,

that is, from the beams, flooring, etc., to which the insulator is fas-

tened. Fig. 16 shows a

good type of porcelain

knob for this class of

wiring. For knob and

tube wiring, it will be

noted that, owing to the

fact that the wiring is

concealed, the conductors

must be kept further apart than in the case of exposed or open wiringon insulators, where, except in damp places, the wires may be run on

cleats or on insulators only one-half inch from the surface wired ovei.

Fig. 16. Porcelain Knob.

24

EI.F.rruiC WIRING 15

Tibrous lubiiiK. I'iWroiis tuliiug is fre<|ueiitly used with knob

and tiil)e wirinj;, and the re^julations governiiifj its use are pven in

Rule 24, Se<'tion S, of thi" Xatiunal KUctric Code. This tuhing, as

state*! in this Ituli,u\uy Ik- useil where it is irn[MJSsililean<l injj)raeti«-al>le

to einj)loy knobs an«l tuU-s, pmvided the difTerenj-e in ]x>tential

bi'twceii the wires is not DVt-r ."iOO volts, and if the wires are not sul>-

i .^. ... Flexible Tubing. "Flexauct" Type.

Courttry of Xational iletal Molding Co., IHltgburg, Pa,

ject to moisture. The cost of wirinj; in flexible fil)roiis tul)ing is

appn)xiniately about the same as the cost of knob and tul)e wiring.

Duplex conductors, or two wires together are not alloweti in fibrous

tubing.

Fibrous tubing is refjuire<l at all outlets where conduit or annore<l

cable is not use<l (as in knob and tube wiring) ; and, as reciuirol by the

Ritle.i, it must extend back from the last j)orcelain suj)port to one inch

beyond the outlet. Fig. 17 shows one make of fibrous tubinij.

Table VIII gives the maximum sizes of conductors (double-

braide<J) which may l)e installe<l in hbrous conduit.

TAHLl: VIII

Sizes of Conductors in I'lbrous Conduit

()1

16 ELECTRIC WIRING

WIRES RUN EXPOSED ON INSULATORS

This method of wiring has the advantages of cheapness, durabiUty,

and accessibihty.

Cheapness. The relative cost of this method of wiring as com-

pared with that of the concealed conduit system, is aboutfifty per cent

of the latter if rubber-covered conductors are used, and about forty

per cent of the latter if weatherproof slow-burning conductors are used.

As the Rules of the Fire Underwriters allow the use of weatherproof

slow-burning conductors in dry places, considerable saving may be

effected by this method of wiring, provided there is no objection to it

Fig. Is. Large l<\eders Run Expose* on Insulators.

from the standpoint of appearance, and also provided that it is not

liable to mechanical injury or disarrangement.

Durability. It Is a well-known fact that rubber insulation has a

relatively short life. Inasmuch as in this method of wiring, the insula-

tion does not depend upon the insulation of the conductors, but on

the insulators themselves, which are of glass or porcelain, this systemis much more desirable than any of the other methods. Of course,

if the conductors are mechanically injured, or the insulators broken,

the insulation of the system is reduced;but there is no gradual dete-

rioration as there is in the case of other methods of wiring, where

IKHip" SiriH't Substation

li.iini stri-ft suliHt.til.iii

SUBSTATIONS OF THK CLEVELAND ELECTRIC ILLUMINATING COMPANY.CLEVELAND. OHIO

\Vuii<-rii..ii ,l£ .SchllrliliT. Arililli'iln, Clrvplniol. Ohla.

KI.KCTItIC WIRING 17

nihlxT is (ItjHMuK'il ujMiii for insulation. This ise.s|K-tially tnie in hot

olatt's, particiihirly whi're thr tfinperature is 120° V. or aUne. For

such cast's, thewt'atht'rj)r(M)f slow-hum in;; coiuUn-tors on |)orceliun

or glass insulators arc esjH*cially reconuntMulc*!.

Accessibility. 'V\w comluctors lu-ing runexjK)se«l, thev niav Ije

readily repaired or reniove«l, or connections may lx> made to the sime.

This inethtjd of

wiring isesjx'cially

reconunended for

mills, factories, and

for large or long

feeder conductors.

Fig. IS shows e.\-

aujples ofe.\jK»sf«l

large fee<ler con-

ductors, installetl in the New York Life In.surance Huilding, NewVork City. For small conductors, up to say No. B. & S.

Gauge each, porcelain cleats may V)e use<l to support one, two,

or three conductors, provided the tlistance between the conduc-

FJg. 19. T\vo-\Vlre Cleat.

Fig. 2a Onc-WJro aoal.FlK- -I' r<>ri'<'litiii hisuUtor fur

Lartcu Couiluctorn.

tors is at least 21 in<hes in a two-wire .system, and 2' inches

U'tween the two outside conductors in a thnv-win* .system where the

|)otential U'tween the outsi<le conductors is not over '.HM.) volts. The

cleat must hold the wire at h-ast one-half in<'h front the s«irface to whi<-li

the cleat is fastene«l; and in damp places the win* must l>e helil at

least «)ne inch fr«>m the .surface wireil over. 'For IjirgiT conductors,

27

18 ELECTRIC WIRING

from No. 6 to No. 4/ OB. & S. Gauge, it is usual to use single porcelain

cleats or knobs. Figs. 19 and 20 show a good form of two-wire

m m m

Fig. 22. Iron Rack and Insulators for Large Conductors.

Courtesy of General Electric Co., Schenectady, iV. Y.

cleat and single-wire cleat, respectively.

For large feeder or main conductors

from No. 4/0 B. & S. Gauge upward, a

more substantial form of porcelain insu-

lator should be used, such as shown in

Fig. 21. These insulators are held in

iron racks or angle-iron frames, of which

two forms are shown in Figs. 22 and 23.

The latter form of rack is particularly de-

sirable for heavy conductors and where a

number of conductors are run together.

In this form of rack, any length of con-

ductor can be removed without disturb-

ing the other conductors.

As a rule, the porcelain insulators

should be placed not more than 4h feet

apart; and if the wires are liable to be

disturbed, the distance between supportsshould be shortened, particularly for small

conductors. If the beams are so far

apart that supports cannot be obtained

every 42- feet, it is necessaiy to provide a

running board as shown in Fig. 24, to

which the porcelain cleats and knobs

can be fastened. Figs. 25 and 26 show

two methods of supporting small con-

ductors, Fcr conductors of No. 8 B. & S.

-Q^oo n̂̂

t>

Fig. 23. Elevation and Plan ofInsulators Held in Angle-

Iron Frames.

28

ELECTRIC WliaXC 19

( Juuge, or over, it is not nect'ssjirv to hrt-ak iin»uiul the ln*ain.s, pmviiletl

they an* not Hahle to Ik- <li.stiirl>e«l ; but thesiij)j>ort.s may Ik* plaeed on

each iH'aiii.

Wliere the dis-

tance l>et\veen the

supp)rts, however,

is greater than 4\

feet, it is usually

necessiiry to provide

Ulterniediate SUJ)- p 1^,34 insulators Moutnod on Running B<i.ira acroshWUe-

|K)rtS,as shown in S,.a<.eU Beams.

Fig. 27, or else to provide a ninning-lMiard. Another nietho<l which

may lie used, where heains are furtlier than 4\ feet ajKirt,is to

TT^-j- M~

Fig. 25. Method of Supporting Small Conductors.

F-^:i

-ct>Flg. 27. Intcrmcdlatu SupiK>n for Conductor Ix'twcvu WlJc-Spaccd Uoam.->.

nin a main along the wall at right angles to the iH'ains, and to

have the individual circuits run lietween and parallel t») the U'ams.

FIk- 2<J. .Mil li' "I of SupiH.! luK .1 .s untilConductor.

Flu- 2H. Condiiciort I*rot<vi.-*i dv WiHklpn(iuard Slrl|>H nu l.ow (Vllluj:.

In low-<'eiliiig rooms, where the conductors are liable f(» injurA*.

it is Usually rei|uirnl that a wtHxIeii guard slri]>Ik* plac«'d on each side

of tlic cdiidiictors, as .shown in Kig. '2S.

Where the conductorspa.s.s through partitions or walls, they must

20

20 ELECTRIC WIRING

be protected by porcelain tubes, or, if the conductors be of rubber, bymeans of fibrous tubing placed inside of iron conduits.

All conductors on the walls for a height of not less than six feet

from the ground, either should be boxed in,or,if they be rubber-covered,

should (preferably) be run in iron conduits; and in conductors having

single braid only, additional protection should be provided bymeans of

flexible tubing placed inside of the iron conduit.

Where conductors cross each other, or where they cross iron pipes,

they should be protected by means of porcelain tubes fastened with

tape or in some other substantial manner that will prevent the tubes

from slipping out of place.

TW0=W1RE AND THREE=WIRE SYSTEMS

As both the two-wire and the three-wire system are extensively

used in electric wiring, it will be well to give some consideration to the

advantages and disadvantages of each system, and to explain them

somewhat in detail.

Relative Advantages. The choice of either a two-wire or a three-

wire system depends largely upon the source of supply. If, for ex-

ample, the source of supply will always probably be a 120-volt, two-

wire system, there w^ould be no object in installing a three-wire system

for the wiring. If, on the other hand, the source of supply is a 120-

240-volt system, the wiring should, of course, be made three-wire.

Furthermore, if at the outset the supply were two-wire, but with a pos-

sibility of a three-wire system being provided later, it would be well

to adapt the electric wiring for the three-wire system, making the

neutral conductor twice as large as either of the outside conductors,

and combining the two outside conductors to make a single conductor

until such time as the three-wire service is installed. Of course, there

would be no saving of copper in this last-mentioned three-wire system,

and in fact it would be slightly more expensive than a two-wire system,

as will be shortly explained.

The object of the three-wire system is to reduce the amount of

copper—and consequently the cost of wiring

—necessary to transmit a

given amount of electric power. As a rule, the proposition is usually

one of lighting and not of power, for the reason that by means of the

three-wire system we are able to increase the potential at which the

turrent is transmitted, and at the same time to take advantage of the

30

ELE(TUH: WIHIN'G 21

With t'lK- iS*- Thrt-e-Wlrc Syst'-m. wiih N<-iitr;il I'uiiducUir btLWi-i-u^' the Two outsldo C'ouJuftors.

j,'rt'atiT rdiciency of the Idwit v()haf,'e lain[). If ciirrt'iit fi»r |Hj\Vfr

{motors, vtv.) only werr to Ik- tninsinittitl, it woiihl U* a siinplf muttiT

to wind the motors, etr., for a hij^her voUafje, ami therel»y retluee the

weight of copjK'r.

If, however, we in-

crease the voltajLje

of lamps, we find

that they are not so

ellitient, nor is their

life so long

thestandanl carbon

lamp, it has been found that the 24()-volt lamp, with the siime

life, retpiires about 10 to 12 ])er cent more current than the cor-

resjM)ndin<; 120-volt lamp. Furthermore, in the case of the more

eflicient lamps recently intr(Hluce<l fsucii as the Tantalum lamp,

Tunj^sten lamj), etc.), it has been foimd impracticable, if not iuijxis-

sible, to make them for pressures alxive 120 volts. For this reason

the three-wire system is employed, for by tiiis metluKl we can use 210

volts across the t)utside conductors, and bv the use of a neutral con-

ductor obtain 120 volts between the neutral and the outside con«luctor,

and thereby l)e enaljUnl to use 12()-volt lamps. Furtherniori', if a

210-volt lamp should ever be j)lace<lon the market that was as economi-

cal as the lower voltage lamp, the result would be that the 240-lSO-

volt svstem would be introduce*!, and 210-volt lamps use«l. As ii

. . matter of fact, this

A. A. has l)een trietl in

I Isevend cities—and

particularly in

2O I'rovidence, Rhode

I IIsland. As a nde,

KIg. 30. I.Hnips .\rr;iiiK''iI III l':ilr-. Ill SiTl«'-i. I)Ui>.Ml.-.liik' wltli llOWCNCr, the 120-Necoii.Hliy for Third or N«"Utral Couduftor.

volt lamp has Urnfound .si> much more .sjjtisfacton' as reganis life, clli«iencv, etc., that

it is nrarlv alwavs <MUi)loveil.

The two-wire system is .so extremely simple that no explanationwhatever is re(|uirnl concerning if.

The three-wire systiMu, howeve.', is somewhat confusing, ano

will now Iv consideretl.

.31

22 ELECTRIC WIRING

Details of Three-Wire System. The three-wire system may be

considered as a two-wire system with a third or neutral conductor

placed between the two outside conductors, as shown in Fig. 29.

This neutral conductor would not be required if we could always have

the lamps arranged in pairs, as shown in Fig. 30. In this case, the

two lamps would bum in series, and we could transmit the current

at double the usual voltage, and thereby supply twice the number of

lamps with one-quarter the weight of copper, allowing the same loss

in pressure in the lamps. The reason for this is, that, having the

lamps arranged in series of pairs, we reduce the current to one-half,

and, as the pressure at which the current is transmitted is doubled,

we can again reduce the copper one-half without increasing the loss

in lamps. We therefore see that we have a double saving, as the cur-

rent is reduced one-half, which reduces the weight of copper one-half,

and we can again reduce the copper one-half by doubling the loss in

volts without increasing the percentage loss. For example, if in one

case we had a straight two-wire system transmitting current to 100

lamps at a potential of 100 volts, and this system were replaced by one

in which the lamps were placed in series of pairs, as shown in Fig. 30,

and the potential increased to 200 volts—100 lamps still being used—we should find, in the latter case, that we were carrj'ing current really

for only 50 lamps, as we would require only the same amount of cur-

rent for two lamps now that we required for one lamp before. Fur-

thermore, as the potential would now be 200 instead of 100 volts,

we could allow twice as much loss as in the first case, because the loss

would now be figured as a percentage of 200 volts instead of a percent-

age of 100 volts. From this, it will readily be seen that in the second

case mentioned, we would require only one-quarter the weight of

copper that would be required in the first case.

It will readily be seen, however, tliat a system such as that out-

lined in the second scheme having two lamps, would be impracticablefor ordinary purposes, for the reason that it would always require the

lamps to be burned in pairs. Now, it is for this very reason that the

third or neutral conductor is required ; and, if this conductor be added,

it will no longer be necessary to burn the lamps in pairs. This, then,

is the object of the three-wire system—to enable us to reduce the

amount of copper required for transmitting current, without increasingthe electric pressure employed for the lamps.

32

ELECTRIC WIRING 23

With reânl to the size of the iieiitnil C(iii(luctor, one im[xjrtant

{Mjiiitmust l>e Ixjnie in iniiul; ami that is, that the Rules of the J^ ational

Electric Code re(|uire the neutral coiKluctor in all interior wiring to Ik?

nia«le at least as lar;;e as either of the two outside eonduetors. The

reasons for this from a fire staiuljxînt are obvious, bec-jiuse, if for

unv reason either of the outside eonduetors l)eeame diseonnected, the

iieutRil wire mi^ht In- re<|uintl to earrv the siime eurrent as the out-

side eonduetors, ami therefore it should In- of the same eapaeity.( )f

course, the chaiiees of such an event haj)j>ening are slight; hut, as

the fire haziird is all-important, this rule nuist Ik- complied with for

interior wiring or in all cases where there would he a jirohahility of

fire. For outside or umh-rground work, however, where the fire

hazjinl would l)e relatively unimportant, the neutral conductor might

lie re»lucetl in size; and, as a matter of fact, it is made smaller than

the outside conductors.

The three-wire system is .sometimes installeil where it is desired

to use the system as a two-wire, 125-volt .system, or to have it arninged

so that it mav he use<l at any time also as a three-wire, 1 2.")-2.')0-volt

system. ( )f course, in onler to do this, it is nece.ssiirv to make the

neutral conductor ef[ual to the combined capacity of the outside con-

ductors, the latter being then connected together to form one con-

ductor, the neutral ln-ing the return conductor. This .system is not

reeonnnended except in such instances, for example, as where an

Lsolated plant of 12.') volts is installed, and where there is a |>ossibility

of changing over at .some future time t«) the three-wire, 12.")-2.")()-volt

system. In such a ca.se as this, however, it would be U-tter. where

po.ssible,to design the i.solated plant for a three-wire, 1 2.")-2.")<>-volt

system originally, and thru to make the ncutr.il < ondiictor the siime

size as each of the two oiilsid*' coMdiictors.

'I'he weight of copper re(|uired in a three-wire .system where the

neutral conductor is the s;ime size as either of the two outside eon«luct-

ors, is 3 "f '!'•'• rei|uini| for a eorresjMinding two-win* .system using

the s;ime voltage of lamps.* It is obvious that this is true, lHM-au.st»,

•V"Tr If. In fhf t wo-wln> nvHU-m. wi< n'prrwnt lln< wi'lulif of oni-li of f »in t wo ron-i|ii< >f rnrhor I In- iiiiin1iIi< riiiniti' »t

Ih' if H« liiiil lhn'<> loiidiiildi .o

I of ru|i|HT nHjulnnl III u 11 . • >«p., mK iwiHwIru nyitli'in IuivImk iIi)< Haiiiv |M<n'^<n(at!i< uf Ionh mhI

If ,; 1 ..li.lm lor wen- iimili' 4 of ' '' '

"x.

M In iw>i iiiK III iiiiilt'r«rouinl work. 1 1 '«»

J k- i » ,-, ,, 1.1 I hat nîiiln^l In the rom»ii>..i,...i,K ...... ., .i. -.. ^

?3

24 ELECTRIC WIRING

as the discussion proved concerning the arrangement shown in Fig.

30, where the lamps were placed in series of pairs, we found that the

weight of copper for the two conductors was one-quarter the weight

of the regular two-wire system. It is then of course true, that, if we

had another conductor of the same size as each of the outside conduct-

ors, we increase theweight of copper one-half, or one-quarter plus

one-half of one-quarter—that is, three-eighths.

In the three-wire system frequently used in isolated plants in

which the two outside conductors are joined together and the neutral

conductor made equal to their combined capacity, there is no saving

of copper, for the reason that the same voltage of transmission is used,

and, consequently, we have neither reduced the current nor increased

tlie potential. Furthermore, though the weight of copper is the same,

it is now divided into three conductors, instead of two, and naturally

it costs relatively more to insulate and manufacture three conductors

than to insulate and manufacture two conductors having the same

total weight of copper. As a matter of fact, the three-wire system,

having the neutral conductor equal to the combined capacity of the

two outside ones, the latter being joined together, is about 8 to 10

per cent more expensive than the corresponding straight two-wire

system.

In interior wiring, as a rule, where the three-wire system is used

for the mains and feeders, the two-wire system is nearly always em-

ployed for the branch circuits. Of course, the two-wire branch cir-

cuits are then balanced on each side of the three-wire system, so as to

obtain as far as possible at all times an equal balance on the two sides

of the system. This is done so as to have the neutral conductor carry

as little current as possible. From what has already been said, it is

obvious that in case there is a perfect balance, the lamps are virtually

in series of pairs, and the neutral conductor does not carry any current.

Where there is an unbalanced condition, the neutral conductor carries

the difference between the current on one side and the current on the

other side of the system. For example, if we had five lamps on one

side of the system and ten lamps on the other, the neutral conductor

would carry the current corresponding to five lamps.In calculating the three-wire system, the neutral conductor is

disregarded, the outer wires being treated as a two-wire circuit, and

the calculation is for one-half the total number of lamps, the per-

34

KLKCTHIC Wild NT, 25

c-entage of loss l)eing hasttl mi the [X)teiitial across the two outside

roiitlia-tors.

The three-wire system is ver}' generally ernployeil in altenuitiiig-

eurreiit secoiuhiry wiring, as nearly all transformers are built with

three-wire c-oniieetions.

While unhalancing will nut alVect the total Idss in the outsiile

coniluet«jrs, yet it tloes atfeet the loss in the lamps, for the reason that

the system is usually calculated on the basis of a perfect balance, and

the loss is divided e<)Ually between the two lamps (the latter Ix'ing

consideretl in series of pairs). If, however, there is ur.ljalaiicing to

a great degree, the loss in lamps will be increase-*!; and if the entire

load is thrown over on one side, the loss in the lamps will lie doubled

on the remaining side, because the total loss in voltage will now (M-cur

in these lamps, whereas, in the case of j)crfect balance, it would l>e

e(jually divided between tlie two groups of lamps.

CALCULATION OF SIZES OF CONDUCTORS

The formula for calculating the sizes of conductors for direct

currents, where the length, load, and loss in volts are given, is as fol-

lows :

The size of eondurtor (in circular mils) is eciual to the curn^rit mullifflicd

by the distance (.one way), niulliplud hy 21.0, duidid by tiie los^ in vuils; or,

^^^^ rxDx2i.r.^(^

in which C = Current, in amperes;D — Distance or length of the circuit (one way, in feet);

V = Loss in volts between the licginnini^ and end of tiie circuit.

The constant (21.0) of this fornnda is derivc«l fn»m the resistjmee

of a mil foot of wire of \)S per <eiit conductivity at 2')° ("enlignide or

77'' FahR-nheit. The resistance t)f a conductor of <inc mil diam-

eter and one foot long, is lO.S at the ti-mperatiire and eondi)<>

tivity named. Wf nndtiply this figure (10.S) by 'J, as the length of a

circuit is usually given as the distance one way, and in onler t»» obtain

the resistance of lM)th conductors in a two-wire circuit, we must

multiply by 2. The formida as alM)ve given, therefore, is for a tw«>-

wire circuit; and in calculating the si/e of conductors in a thri'e-win*

.system, the calcidatioti shouM be made on u (wo-wire Im.sis, as ex-

plained lieri'iiiaflcr.

36

26 ELECTRIC WIRING

Formula 1 can be transformed so as to obtain the loss in a given

circuit, or the current which may be carried a given distance with a

stated loss, or to obtain the distance when the other factors are given,

in the following manner:

Formula for Calculating Loss in Circuit when Size, Current, and Distance are Given

rr _ C X DX 21.6 /^x^ ~ CM y-^)

Formula (or Calculating Current which may be Carried by a Qiven Circuit of Specified

Length, and with a Specified Loss

^^ DX 21.6 V'';

Formula for Calculating Length of Circuit when Size, Loss, and Current to be Carriedare Given

CM XV X .X^= ex 21.6 (4)

Formulae are frequently given for calculating sizes of conductors,

etc., where the load, instead of being given in amperes, is stated in

lamps or in horse-power. It is usually advisable, however, to reduce

the load to amperes, as the efficiency of lamps and motors is a variable

quantity, and the current varies correspondingly.

It is sometimes convenient, however, to make the calculation

in terms of watts. It will readily be seen that we can obtain a formula

expressed in watts from Formula I. To do this, it is advisable to

express the loss in volts in percentage, instead of actual volts lost. It

must be remembered that, in the above formulse, V represents the

volts lost in the circuit, or, in other words, the difference in potential

between the beginning and the end of the circuit, and is not the

applied E. M. F. The loss in percentage, in any circuit, is equal to

the actual loss expressed in volts, divided by the line voltage, multiplied

by 100; or,

P = ^ X 100.

From this equation, we have:

y^ PE100

If, for example, the calculation is to be made on a loss of 5 per cent,

with an applied voltage of 250, using this last equation, we would have:

„ 5X250 ,„. ,^V = -—— = 12.5 volts.

PESubstituting the equation V=

^

in Formula 1 ,we haver

36

KLECrUIC WUtlNG 27

r \tC X D x 21.0

100

C X D X 21.6 X 100

P EC X D X 2.100

P E

This W|iiati()ii it .should he reinemherwl, i.soMprt'.ssttl

in tenn.s of

ajiplieil vollaiijf. Now, .since the pjwer in watts is etjual tt> the applied

voltage mtiltipliid by the current (M'= EC), it follows that

E

\\\ sul)stiiutint; this value of C in the e([uation given above ( C MC'xD X l-MOUv

PE )of current, thus:

C'xD X iMOUv .

, ,

.

,

.

, r ..•

, I

p-= I,tlie fornuila is expresseti \n terms of watts instead

^ir _ W'x D X 2.160 .-X

in which II' = Power in watts transmitted;J) =

I.cngtii of tlio ciriuit (one way)— tliat is, the length of one

conductor;P = Figure rei)rf.scnting the percentage loss;

E*= Ai)j)lie(l voltage.

All the al)ove forniuhe are for calculaticjiis of two-wire cirtiiits.

In making calculations for three-wire circuits, it is usual to make the

calculation on the hasis of the two outside conductors; and in three

wire calculations, the alnne formula' can In- used with a slight miHliii-

cation, as will l)e .shown.

In a three-wire circuit, it is usually a.ssuine«l in making the cid-

culatinii, that the load is e<|Ually l>alance«l on the two sides i)f the

neutral conductor; and, as the |>otential acnt.ss the outside conductors

is douhle that of the corresponding poti-ntial acrt>.ss a two-wire circuit,

it is evident that for the siixuv si/.*- <»f con<luctor the total lo.ss in volts

coulil U- douMnl witiiout increasing the jM-rcentage of loss in lamps.

I'urtlu'rmore, as the load on one side of the neutral c<tnductor, when

the sy^lcin is halaix cd, isvirliially in .series with the load on the

thini side, the curreiu in am|)eres is usually one-half the sum of the

(iirreiilrei|iiired l.y ;dl llie lam|»s. If (' l>e still taken as the total

*NoTr.. llinnoiiitM<r timl I' In Ki>riiiuln> 1 lo 4 rf>|imM'iiiii tlu< voliii Uat, liui tli»l

K In Knrtntiln 8 n'prtwiKM tlii< appili')! vnliiiKo,

37

28 ELECTRIC WIRING

current in amperes (that is, the sum of the current required by all of

the lamps) in Formula 1, we shall have to divide this current by 2,

to use the formula for calculating the two outside conductors for a

three-wire system. Furthermore, we shall have to multiply the

voltage lost in the lamps by 2, to obtain the voltage lost in the two out-

side conductors, for the reason that the potential of the outside com

ductors is double the potential required by the lamps themselves.

In other words, Formula 1 will become :

^^J^CXDX 21.6

2 X FX2CXDX 21.6-

4.'• (6)

in which C = Sum of current required by all of the lamps on both sides of

the neutral conductor;

D = Length of circuit—that is, of any one of the three conductors;

V = Loss allowed in the lamps, i. e., one-half the total loss in the

two outside conductors.

In the same manner, all of the other formulae may be adapted for

making calculations for three-wire systems. Of course the calcula-

tion of a three-wire system could be made as if it were a two-wire

system, by taking one-half the total number of lamps supplied, at

one-half the voltage between the outside conductors.

It is understood, of course, that the size of the conductor in

Formula 6 is the size of each of the two outs de ones; but, inasmuch

as the Rules of the National Electric Code require that for interior

wiring the neutral conductor shall be at least equal in size to the outside

conductors, it is not necessarv' to calculate the size of the neutral

conductor. It must be remembered, however, that, in a three-wire

system where the neutral conductor is made equal in capacity to the

combined size of the two outside conductors, and where the two

outside conductors are joined together, we have virtually a two-wire

system arranged so that it can be converted into a three-wire system

later. In this case the calculation is exactly the same as in the case

of the two-wire circuits, except that one of the two conductors is split

into two smaller wires of the same capacity. This is frequently done

where isolated plants are installed, and where the generators are wound

for 125 volts and it may be desired at times to take current from an

outside three-wire 125-250-volt system.

38

ELE(jriUC WIRING 29

MliTMOI) Ol- PLANMNd A W IkMNOINSIAI.LAIION

Tlif ln>i>iij) it) planiiinj; a wiring iiistallati<»n, is to ^'atlier all

llif (lata wiiirii will allVct fillu-r dirfctly oriiidiri-ctly tlu' .system of

wirinj; and tin- maiiiiiT in wliicli tjic coiKluctors are to U* installed.

These data will iiulude: Kind of l)uildin<r; c-onstnietion (jf Wuilding;

space available for conductors; s«jurce and systenj (jf electric-current

supply; and all details wlii'li will determine the method of wiringto Ir' employetl. These last items materially all'ej-t the cost of the

work, and are usually deterniini'd hy the character of the huilding

and i)y commercial considerations.

jMcthod of Wiring. In a mo<lern fireproof huilding, the only

system of wiring to he recommended is that in which the contluctors

are installed in rigid conduits; although, even in such ca.ses, it mav be

desirable, and economy may Ije effected thereby, to install the larger

feetler and main conductorse.\jK).se<l

on insulators using weatheq)ro<jf

slow-burning wire. This latter method should be u.sc<l, however,

only where there is a convenient runway for the conductors, so that

they will not be crowde<l and will not cross pipes, ducts, etc.. ?.nd

also will not have too many bends .Mso, the local inspection authori-

ties should be consultitl before usiiij;, this metluxl.

For mills, factories, etc., wires e.\jK)seil on cleats or insulators

are usually to be recommende<l, although rigid conduit, flexible con-

duit, or armored cable may be desirable.

In finishe<l buililings, and for extensions of existing i»utlets,

where the wiring could not readilv or cniivenientlv be concealetl.

moulding is generally u.se«|, particularly where cleat wiring or other

ex|»osed methixls of wiring would be objectionable. However, as

has alri-ady Iwen .said, moulding shoidd not Ih' emplovnl when* therv

is any liability to dampness.In finished buildings, particidarly where they are of frame coii-

stniction, flexible steel conduits or arinore<l cable are to be rect)m-

mende<l.

While in new buildings of frame construction, knob ai.d tuU*

wiring are frecjuently employe«l, this mctho«l shouM U' us<'»l «)nK

when* the (|uestioii of first cost is of jirinic ini|M)rtance. \Vhilearmonil

cable will cost approximatciv .'id (o |(M( per cent mon." than knob and

30

30 ELECTRIC WIRING

tube wiring, the former method is so much more permanent and is

so much safer that it is strongly recommended.

Systems of Wiring. The system of wiring—that is, whether

the two-wire or the three-wire system shall be used—is usually deter-

mined by the source of supply. If the source of supply is an isolated

plant, with simple two-wire generators, and with little possibility

of current being taken from the outside at some future time, the

wiring in the building should be laid out on the two-wire system. If,

on the other hand, the isolated plant is three-wire (having three-wire

generators, or two-wire generators with balancer sets), or if the cur-

rent is taken from an outside source, the wiring in the building should

be laid out on a three-wire system.

It very seldom happens that current supply from a central station

is arranged with other than the three-wire system inside of buildings,

because, if the outside supply is alternating current, the transformers

are usually adapted for a three-wire system. For small buildings,

on the other hand, where there are only a few lights and where there

would be only one feeder, the two-wire system is used. As a rule,

however, when the current is taken from an outside source, it is best

to consult the engineer of the central station supplymg the current,

and to conform with his wishes. As a matter of fact, this should be

done in any event, in order to ascertain the proper voltage for the

lamps and for the motors, and also to ascertain whether the central

station will supply transformers, meters, and lamps—

for, if these

are not thus supplied, they should be included in the contract for the

wirmg.Location of Outlets. It is not within the scope of this treatise

to discuss the matter of illumination, but it is desirable, at this point,

to outline briefly the method of procedure.

A set of plans, including elevation and details, if any, and show-

ing decorative treatment of the various rooms, should be obtained

from the Architect. A careful study should then be made by the

Architect, the Owner, and the Engineer, or some other person qualified

to make recommendations as to illumination. The location of the

outlets will depend: First, upon the decorative treatment of the

room, which determines the aesthetic and architectural effects; second^

upon the type and general form of fixtures to be used, which shoula

be previously decided on; third, upon the tastes of the owners or

40

FLECTUic wiiiixn :n

occupiUits ill rt'ijaril to illiiitiiiiatiuti in jjcntTal, us it is fouiul that

tastes van* widciv in rf^anl to ainoiiiit and kiiul of illiiiiiiiiation.

The location of the outlets, ami the iiuiiiImt (»f li^'hts re<|uire«i

at eaih. having iH^en (leteniiinnl. iht- outlets shuultl Ik* marked on

the j)laMs.

The Architect should then Im.- consulted as to the hx-ation of tiie

centers of distriliution, the available jM)ints for the risers or fettlers,

ami the available space for the branch circuit coinluctors.

In re<;ard to the rising fMint.s for the ftcdrr.t and mahut, the fol-

lowing precautions shoidd Ik- useil in selecting chases:

1. The space sliould be amply large to acfomriodate all (lie feeders and

mains lik«ly to rise at that j;ivcn f)oint. This seems trite and unii'

but it is the most usual trouble with tha-ses for risers. Foniierly a; ...; .s

and builders paiil little attention to the refiuirements for chjuses for electrical

work; but in these later days of 2-incii and 2i-inch conduit, they realize that

these pipes are not so invisible and mysterious jis the force they serve to dis-

tribute, particularly when twenty or more such conduits must be stowed awayin a buihliiiR where no special provision hits been made for them.

2. If possible, the space should be devoted solely to electric wiring.

Steam pi|)es are objectionable on account of their tem|)erature; and these and

all other i)ipes are objectionable in the same space occupied by the electrical

conduits, for if the sjjace i)roves too small, the electric conduits are the first to

Ik* crowded out.

The chase, if possible, should be continuous from the cellar to the roof,

or as far as needed. This i.s neces.sary in ortler to avoid unnecessary bends or

elbows, which are objectionable for many reasons.

In .similar manner, the location of c(//-<</// cabintfs or ditlrihuling

centers .shoidd fulfil the following re(|iiirements:1. They shoukl be jicce.ssible at all times.

2. They should be |)laced sufTicienily do.se together to prevent the cir-

cuits from being too long.

3. Do not place them in too prominent a position, as that is obje<*tionable

from the .Architect's point of view.

4. They should be placeil as near a.s po.s.sible to the risking ch.'uses. in

order to shorten the feeders and mains supplying them.

Having determiiHMl the .system and meth(Hl of wiring, the l(H-ation

of outlets and distributing centers, the next step is to lay out the liranch

cirruil.H sup|)lyiiig tlu' various outlets.

Heforc starling to lay out the branch ciniiits, a drawing sh«»wing

the floor construction, and showing the space In'tween the top of the

JM-ams and ginlersand the flooring, should Im* obtitineil fmiii the Archi-

tect. In f -proof buildings of iron or sl«'el constnK'tion. it is almost

the invariable jmicticc, where the W(»rk is to Ik* co^lX'all^l, to nin <lu'

41

32 ELECTRIC WIRING

conduits ove^ the beams, under the rough flooring, carrying them

between the sleepers when running parallel to the sleepers, and notch-

ing the latter when the conduits run across them (see Fig. 31). In

wooden frame buildings, the conduits run parallel to the beams and

to the furring (see Fig. 32); they are also sometimes run below the

Finished Floor^Kii^mmm^ss^i^^xm.'iiii'i^j^sMfZ'mss&mssms^^^mim!^^^^

JRoia.gh Flooring/

Fig. 31. Running Conductors Concealed under Floor in Fireproof Building:.

beams. In the latter case the beams have to be notched, and this is

allowable only in certain places, usually near the points where the

beams are supported. The Architect's drawing is therefore necessary

in order that the location and course of the conduits may be indicated

on the plans.

The first consideration in laying out the branch circuit is the

number of outlets and number of lights to be wired on any one branch

circuit. The Rules of the National Electric Code (Rule 21-D) require

that "no set of incandescent lamps requiring more than GGO watts,

whether grouped on one fixture or on several fixtures or pendants,will be dependent on one cut-out." While it would be possible to

have branch circuits supplying more than 660 watts, by placing various

cut-outs at different points along the route of the branch circuit, so

as to subdivide it into small sections to comply with the rule, this

method is not recommended, except in certain cases, for exposed wiringin factories or mills. As a rule, the proper method is to have the

cut-outs located at the center of distribution, and to limit each branch

circuit to 660 watts, which corresponds to twelve or thirteen 50-watt

lamps, twelve being the usual limit. Attention is called to the fact

that the inspectors usually allow 50 watts for each socket connected

to a branch circuit; and although 8-candle-power lamps may be

placed at some of the outlets, the inspectors hold that the standard

lamp is approximately 50 watts, and for that reason tb*?"? is alwaysthe likelihood of a lamp of that capacity being used, and their inspec-

42

KLECrUIC WIHIXG 33

tion is Imstil mi that assumption. Tlierefore, to t-omply with the

rt*<|uirfnR'iits,an allowance of not more than twelve himps j>er hranch

circuit .shoultl Ix" made.

In onlinarA- practice, howcscr, it is best to reduce this number

still fur'licr, so as to make allowance for future extensions or to increase

the nuniher of lamjjs that may hej)lacetl

at any outlet. For this

rea.son, it is wise to keep the numljer of the outlets on a circuit at the

lowest p)int consistent with econ(»mical wiriniij. It has iK-en pmven

by actual practice, that the best results are obtaine«l by limitinj; the

nunil>er to five or six outlets on a branch circuit. Of course, where

all the outlets have a .single lijjht each, it is fre(|uently nece.ss5ir\", for

rea.sons of economy, to increase tiiis miml)cr ti» ei<jht, ten, and, in

some ca.ses, twelve outlets.

Wv have already referred to the location ot" the wires or conduits.

This (|uestion is f;enerally settlwl by the peculiarities of the constnic-

tion of the building'. It is nece.s.sarj' to know this, however, In'fore

laving out the circuit work, as it frecjuently determines the course of

a circuit.

Now, as to the course of the circuit work, little nee<l Im? .said,

as it is largely influenced by the relative position of the outlets, cut-

Ksi.£r-' Nv- tr.-,- i .f- Jtfr— -

stud orWall

Wooden BecAii.

Furring Strips

•ing

:bel

Lathing^

I'l^;. s-s lUiuuluf Comluclors ConoeaUM undor Floor In WotHlcu Framo Uuiiaiiit;,

outs, switches, etc. Hetwfi'U the cut-out box and the first outlet, and

iH'tween the outlets, it will havi- to l)e diiidiil, however, whether

the circuits .shall nin at right angles to the walls of the buiKling or

HKnn, or whether they .shall run direct from one point t(» another,

irn"s|K'ctive of the angle they make to the sli-eiwrs or U-am.s. Of

cours<', ill the latter case, the advantages are that the cost is .s<ime-

what less and (In- numlK-r of cIIkiws and Ik-iuIs is nxlucetl. If the

43

34 ELECTRIC WIRING

tubes are bent, however, instead of using elbows, the difference in

cost is usually very slight, and probably does not compensate for the

disadvantages that would result from running the tubes diagonally.

As to the number of bends, if branch circuit work is properly laid

out and installed, and a proper size of tube used, it rarely happensthat there is any difference in "pulling" the branch circuit wires.

It may happen, in the event of a very long run or one having a large

number of bends, that it might be advisable to adopt a short and

most direct route.

Up to this time, the location of the distribution centers has been

made solely with reference to architectural considerations; but they

must now be considered in conjunction with the branch circuit work.

It frequently happens that, after running the branch circuits

on the plans, we find, in certain cases, that the position of centers of

distribution may be changed to advantage, or sometimes certain

groups may be dispensed with entirely and the circuits run to other

points. We now see the wisdom of ascertaining from the Architect

where cut-out groups may be located, rather than selecting particular

points for their location.

As a rule, wherever possible, it is wise to limit the length of each

branch circuit to 100 feet; and the number and location of the dis-

tributing centers should be determined accordingly.

It may be found that it is sometimes necessary and even desirable

to increase the limit of length. One instance of this may be found in

hall or corridor lights in large buildings. It is generally desirable,

in such cases, to control the hall lights from one point; and, as the

number of lights at each outlet is generally small, it would not be

economical to run mains for sub-centers of distribution. Hence,

in instances of this character, the length of nms will frequently exceed

the limit named. In the great majority of cases, however, the best

results are obtained by limiting the runs to 90 or 100 feet.

There are several good reasons for placing such a limit on the

length of a branch circuit. To begin with, assuming that we are going

to place a limit on the loss in voltage (drop) from the switchboard to

the lamp, it may be easily proven that up to a certain reasonable

limit it is more economical to have a larger number of distributing

centers and shorter branch circuits, than to have fewer centers and

longer circuits. It is usual, in the better class of work, to limit the

44

ELECTRIC WIRING 35

loss in V()lta>,'»' in anv Ijianth < ircuit toa|)|)rit\iinat('ly

nnr volt. A.v

suniinf^ this limit (one volt loss), it can rtMilily l»c' calcnlati-il (hat the

nuinl)er of lijjhts at one outlet which may l»e conne<-te(| on a hrancli

circuit 1(X) feet long (using NO. I 1 i^ t.^ S. wire), is four; or in the

ca.se of outlets having a single light each, five outlets may l»e con-

necte<l on the circuit, the first In-ing tlO feet frcrn the cut-<jut, the others

U'ing 10 feet apart.

These e.xaniples are selecteil sini[)ly to show that if the hninch

circuits are much longer than KM) feet, the loss must l)e increa.si-*!

to more than one volt, or else the numl)er of lights that may Ih* con-

nectcil to one circuit must lie reduced to a verj' small ijuantity, pnj-

videil, of course, the size of the wire remains the .sjime.

Either of these alternatives is objectionable—the first, on the

score of regulation; and the second, from an economical standp>int.

If, for instance, the loss in a branch circuit with all the lights tunie<l

on is four volts (assuming an extreme case), the voltage at which u

lamp nn that circuit burns will vary from four volts, depending on the

numlKT of lights burning at a time. This, of course, will cau.se the

lamp to burn below candle-power when all the lamps are turne<l on,

or else to (liiiiiiii.sh its life by burning above the proper voltage when

it is the only lamp burning on the circuit. Then, too, if the drop in

the branch circuits is increa.scd, the sizes of the feeders and the mains

must be correspondingly increased (if the total loss remains the .sjune),

thereliy increasing their cost.

If the mimber of lights on the circuit is decreasc<l, we do not u.se

to go<Hl advantage th»' available carrA'iiig capacity of the wire.

( )f cour.se, one solution «(f the problem would Ik* to increase the

size of the wire for the branch circuits, thus n'ducing the »lrop. This,

however, would not be desind)le, except in certain cases where there

were a few long cin nils, >u( li as for corridor lights or other six^-ial

ontrol circuits. In such instances as these, it wouM be U'ttcr to

increase the sizes of the bninch circuit to NO. 12 or even No. 10

H. & S. fiauge condu<'(ors, than to incn-asc the numU'r of «vnters

)f distribution for the sjikc of a few circuits only, in order to rt<duct*

the nnmlK-r of lam|)s (or loss) within the limit.

The melhiKl iif calcidating the loss in conductors has Ikhmi given

ol.sewheir; but it must br lM»rne in mind, in cjdculating the lo.ss of n

branch circuit supplying mon- than one outlet, that .sej^inite calcu-

•is

36 ELECTRIC WIRING

lations must be made for each portion of the circuit. That is, a

calculation must be made for the loss to the first outlet, the length in

this case being the distance from the center of distribution to the first

outlet, and the load being the total number of lamps supplied by the

circuit. The next step would be to obtain the loss between the first

and second outlet, the length being the distance between the two out-

lets, and the load, in this case, being the total number of lamps sup-

plied by the circuit, minus the number supplied by the first outlet;

and so on. The loss for the total circuit would be the sum of these

losses for the various portions of the circuit.

Feeders and Mains. If the building is more than one story, an

elevation should be made showing the height and number of stories.

On this elevation, the various distributing centers should be shown

diagrammatically; and the current in amperes supplied through

each center of distribution, should be indicated at each center. The

next step is to lay out a tentative system of feeders and mains, and to

ascertain the load in amperes supplied by each feeder and main.

The estimated length of each feeder and main should then be deter-

mined, and calculation made for the loss from the switchboard to

each center of distribution. It may be found that in some cases it

will be necessary to change the arrangement of feeders or mains, or

even the centers of distribution, in order to keep the total loss from the

switchboard to the lamps within the limits previously determined.

As a matter of fact, in important work, it is always best to lay out the

entire work tentatively in a more or less crude fashion, according to

the "cut and dried" method, in order to obtain the best results, because

the entire layout may be modified after the first preliminaiy layout

has been made. Of course, as one becomes more experienced and

skilled in these matters, the final layout is often almost identical with

the first preliminary arrangement.

TESTING

Where possible, two tests of the electric wiring equipment should

be made, one after the wiring itself is entirely completed, and switches,

cut-out panels, etc., are connected; and the second one after the

fixtures have all been installed. The reason for this is that if a groundor short circuit is discovered before the fixtures are installed, it is

more easily remedied; and secondly, because there is no division oi

46

KLECrUIC WIUING 37

the re.sjM)nsil)ility,as there might lie if the first test were made only

after the fixtures were installe<l. If the test sliows no gnninds or

short c-ireuits l)efore the fixtures are installetl, and one does develop

after tliey are installetl, the troulde, of course, is that the short circuit

or i:n)un(l is one or more of the fixtures. As a matter of fact, it is a

wise plan always to make a separate test of each fixture after it is

deliverctl at the huilding and l>efore it is installnl.

While a magneto is largely used for the pur|)ose of testing, it is

at liest a cruile and unreliable niethcxl. In the first place, it does

not give an indication, even approximately, of the total insulation

resistance, but merely indicates whether there is a ground or sliort

circuit, or not. In some instances, moreover, a magneto test has

let! to serious errors, for reasons that will he cxplainetl.- If, as is

nearly always the case, the magneto is an alteniating-current instru-

ment, it may sometimes happen—

particularly in long cables, and

especially where there is a lead sheathing on the cable—that the

magneto will ring, indicating to the uninitiated that there isa gn)unti

or short circuit on the cable. This may l)C, and usually is, far fn)m

being the case; and the cause of the ringing of the magneto is not a

ground or short circuit, but is due to the capacity of the cal)le, which

acts as a condenser under certain conditions, since the magneto pnxluc-

ing an alternating current repeatetlly charges and discharges the cable

in opjKtsite directions, this changing of the current caiising the magneto

to ring. Of course, this defect in a magneto could be lemedietl by

using a commutator and changing it to a dirc(t-<urrent machine;

but as the metluKl is faulty in itself, it is hardly worth while to ilo this

A portable (jalvanomeicr with a resistance Ih)X and \\heat.stone

bridge, is .sometimes employnl; lii;( this nictluxl is objectionable

Ix'cau.se it requires a sju^cialinstniment which cannot U> useil for

nmnv othtT |)uqH).ses. Furthermore, it rc<|uin's more skill and time

to use than the voltmeter meth(Kl, which will now U* descrilHsl.

The advantage of the voltmeter method is that it rtHpiires merely

H dircct-iurrcnt voltmeter, which can U- ustil for many other puiixises,

and which all engineers or contractors should|k>ss<'ss, together with

a l)ox of cells having a {K)tentialof preferably oxer 'M volts. The v«»lt-

meter shot dd have n scale of not over l.V) volts, for the reason that if

the scah" «»n whicli the battery is u.se»| covers t<H» wide a nmge (sjiy

1,()(H) volts) the n*adings might Ik> .so small as to make the te.st inac-

47

38 ELECTRIC WIRING

curate. A good arrangement would be to have a voltmeter having

two scales—say, one of 60 and one of 600—which would make the

voltmeter available for all practical potentials that are likely to be

used inside of a building. If desired, a voltmeter could be obtained

with three connections having three scales, the lowest scale of which

would be used for testing insulation resistances.

Before starting a test, all of the fuses should be inserted and

switches turned on, so that the complete test of the entire installation

can be made. When this has been done, the voltmeter and battery

should be connected, so as to obtain on the lowest scale of the volt-

meter the electromotive force of the entire group of cells. This

connection is shown in Fig. 3.3. Immediately after this has been done,

the insulation resistance to be tested

is placed in circuit, whether the

insulation to be tested is a switch-

board, slate panel-board, or the

entire wiring installation; and the

connections are made as shown in

Fig. 34. A reading should then

again be taken of the voltmeter;

and the leakage is in proportion

to the difference between the first

and second readings of the volt-

meter. The explanation given below

will show how this resistance may be calculated : It Is evident that

the resistance in the first case was merely the resistance of the volt-

meter and the internal resistance of the battery. As a rub, the internal

resistance of the battery is so small in comparison x^^ith the resistance

of the voltmeter and the external resistance, that it may be entirely

neglected, and this will be done in the following calculation. In the

second case, however, the total resistance in circuits is the resistance

of the voltmeter and the batter}-, plus the entire insulation resistance

on all the wues, etc., connected in circuit.

To put this in mathematical form, the voltage of the cells maybe indicated by the letter E; and the reading of the voltmeter when

the Insulation resistance is connected by the circuit, by the letter E'.

Let R represent the resistance of the voltmeter and Rx represent the

insulation resistance of the installation which we wish to measure.

Fig. 33. Connections of Voltmeter andBattery for Testing Insulation

Resistance.

48

Ei.Kr'Tiac wiiiixG •'.')

It is a fact wliicli the nnuleruiul(Jiil)te<lly knows, that the K. M. F. as

indicatetl hy the voltmeter in Fifj. 3-4 is inversely proportional to the

resistance: that is, the greater the resistance, the lower will l>e the

reatling on the voltmeter, as this reading indicates the leakage or cur-

rent passing thn>ugh the resistance. Putting this in the shape of a

formula, we have from ilie theor}* of proportion:

/•: : K' :: li + U, : W ;

or,

Transposing,

an<l

E' li + K' lix -- i: R.

E' lix - E li - E' n = li {E-E'),

R{E-E')Rx =E'

Bu3

>-Bua

Fig. 34. lu.sulatlou Ut.-!.l.-.t;iuco I'laceU lu Circuit, l{o;iJy |. r

Testing.

Or, expres.sed in wortls, the in.sulation resistance is ecjual to the resist-

ance of the volt-

meter 7nultipllcd hy

the (lifTerence l->e-

tween the first rea<l-

ing (or the voltage

in the cells) and

the .second reading

(or the reading of

the voltmeter with

the insulation re-

sistance in series with the voltmeter), divided by this last reading of

the voltmeter.

Example. A.s.sume a resistance of a voltmeter (/?) of 2(1.(HK) ohms,

and a voltage of the cells (E) of 30 volts; and suppo.sc that the insula-

tion rcsistatue test of a wiring installation, including switchlM>ard,

feetlcrs, hramch ciniiils, j)ancl-l)oarils, etc., is to he mailc, the insula-

tion resistance U-ing reprcst'iited l>y the letter /ij.

. Hy suhstituting

in the forniiila

,,R (E - E')

and a.vsuining tiiat tin- reading of tin- voltmcttr with tlic insidation

n'sistjince conne<'te<l is o, we have:

•JO,(KMI ".)

A' ",

- l(K),(M)OolilllK.• »

ll tin ic.sl .-allows an excc'.ssive ainoui>l of h'akag**, or a groinul or

40

40 ELECTRIC WIRING

short circuit, the location of the trouble may be determined by the

process of elimination—that is, by cutting out the various feeders

until the ground or leakage disappears, and, when the feeder on which

the trouble exists has been located, by following the same process

with the branch circuits.

Of course, the larger the installation and the longer and more

numerous the circuits, the greater the leakage will be; and the lower

will be the insulation resistance, as there is a greater surface exposed

for leakage. The Rules of the National Electric Code give a sliding

scale for the requirements as to insulation resistance, depending uponthe amount of current carried by the various feeders, branch circuits,

etc. The rule of the National Electric Code (No. 66) covering this

point, is as follows:

"The wiring in any building must test free from grounds; i. e., the com-

plete installation must have an insulation between conductors and between

all conductors and the ground (not including attachments, sockets, recepta-

cles, etc.) not less than that given in the following table:

Up to 5 amperes 4,000,000 uhms10 "

2,000,000"

25 "800,000

"

50 "400,000

"

100 "200,000

"

200 "100,000

"

400 "50,000

"

" 800 "25,000

"

"1,600

"12,500

"

"The test must be made with all cut-outs and safety devices in place. If

the lamp sockets, receptacles, electroliers, etc., are also connected, only one-

half of the resistances specified in the table Avill be required."

ALTERNATING-CURRENT CIRCUITS

It is not within the province of this chapter to treat the various

alternating-current phenomena, but simply to outline the modifications

which should be made in designing and calculating electric light

wiring, in order to make proper allowance for these phenomena.The most marked difference between alternating and direct cur-

rent, so far as wiring is concerned, is the effect produced by self-

induction, which is characteristic of all alternating-current circuits.

This self-induction varies greatly with conditions depending uponthe arrangement of the circuit, the medium surrounding the circuit,

the devices or apparatus supplied by or connected in the circuit, etc.

50

ELErnur WIRING 41

For exainpli", if a ti)il liii\ iiig a resistant-e of KM) ohms is iiuludetl in

tlie circuit, a current of «)iie ampere can Ix? passotl through the c-oil

with an electric pressure of KM) vohs, if direct current is use«l; wliile

it might re<|uire a jK)tential of several luuulretl volts to pass a current

of «Mie ampere if altenuiting-<urrent were usi-d, dejR'nding u|)on the

numluT of turns in tlie coil, whether it is wound on iron or some otiier

non-magnetic material, etc.

It will l)e seen from this example, that greater allowance shouKl

be made for self-inducti(»ii in laying out and calculating alteniating-

current wiring, if the conditions arc such that the self-induction will

be aj)precial»le.

( )n accovmt of self-induction, the two wires of an alteniating-

current circuit must never Ik? installed in separate in»n or stivl con-

duits, for the reason that such a circuit would l)e virtually a choLr coil

consistini: of a sinirlc tuni of wire wound on an iron core, and the self-

induction would not only reduce the current passing through the cir-

cuit, but also might prinlucc iieating of the ironpijx-*.

It is for this

reasfm that t\\e National /'^/cc/r/cCw/p rc(|uircs conductors constitut-

ing a given circuit to be placed in the same conduit, if tluit conduit

is iron or steel, whenever the said circuit is intended to carrA', or is

liable to carry at some futur? time, an r.lternating current. This dmvs

not mean, in the case of a two-phase circuit, that all four conductors

nec<l Ik; placed in the same conduit, but that the two conductors of a

given pha.se nuist be placed in the same conduit. If, however, the

three-wire svstem Ik* u.se<l for a two-nha.se sv.stem, all three conductors

should be placed in the siime conduit, as .should also Ik- the ca.sc in a

three-wire three-phase system. ( )f cniirM', in a single-pha.se two- or

three-wire .system, the conductors should all be placnl in the .sjune

ti^ndiiit.

In calculating circuits carrAiiig alternating cnrrciit, no alltiwance

u.->uallv should Ik made for s«'lf-induction when the conductors of the

.same circuit are place<l clo.se together in an iron conduit. When,

however, the conductors aire nm exposnl, or are .sepanitetl fnun each

other, calculation should In- made to determine if the elTects »)f .self-

induction are great enough to «ause an appre<iabK' inductive tlrop.

There are s<>vend metlnnls of calculating this droj» «lue to .self-induc-

tion—one bv formula, an<! one by a mathematical metluMl which will

Ix' de.scrilK'd.

61

42 ELECTRIC WIRING

Skin Effect. Skin efFect in alternating-current circuits is caused

by an incorrect distribution of the current in the wire, the current

tending to flow through the outer portion of the wire, it being a well-

known fact that in alternating currents, the current density decreases

toward the center of the conductor, and that in large wires, the current

density at the center of the conductoris relatively quite small.

The skin effect increases in proportion to the square of the diam-

eter, and also in direct ratio to the frequency of the alternating current.

For conductors of No. 0000 B. & S. Gauge, and smaller, and for

frequencies of 60 cycles per second, or less, the skin effect is negligible

and is less than one-half of one per cent.

For very large cables and for frequencies above 60 cycles per

second, the skin effect may be appreciable; and in certain cases, allow-

ance for it should be made in making the calculation. In ordinary

practice, however, it may be neglected. Table IX, taken from Alter-

nating-Current Wiri7ig and Distribution, by W. R. Emmet, gives the

data necessary for calculating the skin effect. The figures given in

the first and third columns are obtained by multiplying the size of the

conductor (in circular mils) by the frequency (number of cycles per

second); and the figures in the second and fourth columns show the

factor to be used in multiplying the ohmic resistance, in order to

obtain the combined resistance and skin effect.

TABLE IX

Data for Calculating Skin Effect

Product of CircularMils X Cycles per Sec.

ELECTRIC WIRIXG 43

nuitual iiitluction takes place. The amount of tliis iiulucetl K. M. F.

set up ill one circuit by a parallel current, is dejH-nilent u|K)n the cur-

rent, the fre<|uency, the leiij,'ths of the circuits runniiifj; parallel to each

other, and the ri-lative positions of the conductors constituting tlje

s;iid circuits.

I iider onlinary conditions, and except for long circuits carrying

high jMttentials, the elYect of nuitual induction is .so slight as to be

negligible, unless the conductors are iinj)ro[)erly arninged. In onlcr

to prevent nuitual induction, the conductors constituting a given

circuit should l)e groupeil together. Tigs. .3.j to 31), inclusive, show

o

o

o

o

o

o

o

o

l€)00O Att. .035 Volts,

7200 Alt. .016 Volts.

O

o

Fig. 35.

Fig. 36.

Fig. 37.

Fig. 38.

Fig. 39.

16,000 Alt.

7200 Alt.

.015 Volts.

.0065Vo1ts.

16,000 Alt. .070 Volts.

7200 Alt. .032 Volts.

le^ooo Alt. .006 Volts.

7200 Alt. .0027Volts,

lepoo Alt. MS Volts.

7^00 Alt .CSO Volts,

Various Groupings of Conduciors In Two Two-Wlro Circuits, (ilvliig VurlousKtlecU of Uiiluotioii.

five arrangements of two two-wire circuits; and show how relatively

small the effect of first induction is when the conductors are j)n)iHTly

arrangc<l. as in Fig. .'{S, and how relatively large it may Ik- when im-

j)ri>perlv arninged, as in Fig. '^*^. Thcs«' diagrams are taken from

a piil)lication of Mr. Charles F, Scott, enfitletl Pohiphasf Traus-

miiitum, i.ssue<l by the Westinghou.se I'lectric & Manufacturing

Companv.Line Capacity. The clTc< t of capacity is usually negligible,

except in long tnmsmi.ssion lines where high |M)tcntials art* u.s»\l; no

calculations or allowance need Im- made for capat'itv, for ortlinar>'

circuit.H

53

<t4 ELECTRIC WIRING

Calculation of Alternating=Current Circuits. In the instruction

paper on "Power Stations and Transmission," a method is given for

calculating alternating-current lines by means of formulse, and data are

given regarding power factor and the calculation of both single-phase

and polyphase circuits. For short lines, secondary' wiring, etc., how-

ever, it is probably more convenient to use the chart method devised

by Mr. Ralph D. Mershon, described in the American Electrician of

June, 1897, and partially reproduced as follows:

DROP IN ALTERNAT1NQ=CURRENT LINES

When alternating currents first came into use, when transmission

distances were short and the only loads carried were lamps, the ques-

tion of dro'p or loss of voltage in the transmitting line was a simple one,

and the same methods as for direct current could without serious

error be employed in dealing with it. The conditions existing in

alternating practice to-day—

longer distances, polyphase circuits,

and loads made up partly or wholly of induction motors—render

this question less simple; and direct-current methods applied to it

do not lead to satisfactory' results. Any treatment of this or of

any engineering subject, if it is to benefit the majority of engineers,

must not involve groping through long equations or complex diagramsin search of practical results. The results, if any, must be in avail-

able and convenient form. In what follows, the endeavor has b?en

made to so treat the subject of drop in alternating-current lines that

if the reader be grounded in the theor}' the brief space devoted to

it will suffice; but if he do not comprehend or care to follow the

simple theory involved, he may nevertheless turn the results to his

practical advantage.

Calculation of Drop. Most of the Hiatfer heretofore published

on the subject of drop treats only of the inter-relation of the E. M. F.'s

involved, and, so far as the writer knows, there have not appeared

in convenient form the data necessarj' for accurately calculating this

c(uantity. Table X (page 47) and the chart (page 46) include, in a

form suitable for the engineer's pocketbook, everj'thing necessary

for calculating the drop of alternating-current lines.

The chart is simply an extension of the vector diagram (Fig. 40).

giving the relations of the E. M. F.'s of line, load and generatoi. In

54

KI.K("ri:it' \V!i;!\T, 45

Fif;. -10, A' is the gfru-ratur K. M. 1'.; e, the E. M. F, iinpresstil uponthe lu;ul

; c, that conijM)neiit of /•' which overcomes the hack 1*2. M. F.

(Uie to the impeilance of the Uiic. The coni|xjnent c is made up of two

components at rijjht aiif^les to eacli other. One is a, tlie comjKJuent

overcoming the III or hack !•'. M. 1'. ihic to resistance of the Hue,

Tlie other is h, the component overcoming the reactance E. M. F. or

hack E. M. F. (hie to the aUernating field set up anjund the wire hy

the current in the wire. "^I'he drop is the ilill'crcnce iK-tween K ami

e. It is (/, the ratlial ilistance l)etween two circular arcs, one of which

is drawn with a radius c, and the other with a radius E.

The cliart is maile by striking a succession of circular arcs with

as a c e n t e r. v

The radius of the

smallest circle cor-

res|K)nds to e, the

E. M. F. of the

load, which is taken

as 100 per cent.

The radiiof the suc-

ceeding circles in-

crease by 1 per cent

of that of the small-

est circle; and, as

the radius of the

last or largest cir-

cle is 110 j)er cent

of that of the smallest, the chart answers for drops uj) to 10 jxr cent of

the E. M. V. delivere<l.

The tenns rcsittaiicv rolls, rr.si.stanrr K. M. /•'., mirtanci' ivlts,

and uarlancc K. M. /•'., refer, of course, to ihc voltages for oven-om-

ing the back 1',. M. I'.'s due lo resistance and reactance respectively.

The figures given in the table under the heatling "Hesistaiice-Volts

for Onir .\m[M're, etc." are simply tin* resistances of 2,0(K) fe«-t of the

various sizes of wire. The values given under the heading "Kea«t-

ance-\'olts, etc.," are, a part of ihem, calculatnl-fntm tables ]iublished

simw time agr) by Messrs. Houston and Keimelly. The remainder

were obtained by using Maxwell's fonnula.

The explanation given in the taltle ai-companying the chart

--d --JFig. iO. Vector Diagram.

56

46 ELECTRIC WIRING

•T ,8LOAD POWER FACTORS

.9 O lO 20 30DROP IN PERCENT OF E.tt.F. OEUVEREO

Chart for Calculating Drop in Alternating-Current Lines.

56

ELECTRIC WIRING 47

TABLE X

Data for Calculating Drop In Altcrnatinjj-Currcnt Lines

To be u-.<xl 111 iiiDjumtl.iii Willi I'liart i>u ojjjx.iUt! put;<?.

i> '••'•' •'tbie, palculat« the /?'»J<<an^<- I'o?^* un.l tin- /.'.i •fjri. .• I'.f'i In the

Ijnr r crnt finh 1h uf tho K. M. FStjir 111 oil tfi'- '-^'irt wli.T'- tht* VHrc.'

i>..wirtat.i..r ..r 11.. 1...1.1 111'- ' ''^ 1"

K. M. K. h<>rl/...m;illv iiiid ' .t tluis•

1. ... , . ... .,,.., . h lli« l;k ..,

.... ^. ...o

M. K. ili'llvi.rfil :ii ttu< t-inl uf ihe line, fcvery tvniti circto• lit ilr.ii) •<> whlih It (<irr'>i)>iiiiW.

48 ELECTRIC WIRING

(Table X) is thought to be a sufficient guide to its use, but a few

examples may be of value.

Problem. Power to be delivered, 250 K.W.; E. M. F. to be delivered,

2,000 volts; distance of transmission, 10,000 feet; size of wire. No. 0; distance

between wires, 18 inches; power factor of load, .8; frequency, 7,200 alterna-

tions per minute. Find the line loss and drop.

Remembering that the power factor is that fraction by which

the apparent power of volt-amperes must be multiplied to give the

true power, the apparent power to be delivered is

^^^^•^^- =312.5 apparent KW..o

The current, therefore, at 2,000 volts will be

2,000=^ -^6 .25 amperes.

From the table of reactances under the heading "18 inches," and

corresponding to No. wire, is obtained the constant .228. Bearingthe instructions of the table in mind, the reactance-volts of this line

are, 156.25 (amperes) X 10 (thousands of feet) X .228= 356.3 volts,

which is 17.8 per cent of the 2,000 volts to be delivered.

From the column headed "Resistance-Volts" and corresponding

to No. wire, is obtained the constant .197. The resistance-volts

of the line are, therefore, 156.25 (amperes) X 10 (thousands of feet)

X .197=307.8 volts, which is 15.4 per cent of the 2,000 volts to be

delivered.

Starting, in accordance with the instructions of the table, from

the point where the vertical line (which at the bottom of the chart

is marked "Load Power Factor" .8) intersects the inner or smallest

circle, lay off horizontally and to the right the resistance-E. M. F. in.

per cent (15 .4) ;and jrom the point thus obtained, lay off vertically the

reactance-E. M. F. in per cent (17.8). The last point falls at about

23 per cent, as given by the circular arcs. This, then, is the drop, in

per cent, of the E. M. F. delivered. The drop, in per cent, of the genera^

tor E. M. F. is, of course,

2318.7 per cent.

100+23

The percentage loss of power in the line has not, as with direct

current, the same value as the percentage drop. This is due to the

fact that the line has reactance, and also that the apparent power

58

<H.

az<

3 :. I

J ^ 5- - ;«

s "l •*

*1

> < fi

fr-^ P

S > ^

|4 I

-J ;; %-

f 'r J*

X a

Booo:

(Jz

Ill < I'UiC WIRING 49

(IfliviTttl to (111- IojmI is nut iilctilical with tlu* tnu- |Ki\ver— tlmt Ls,

the Imul powtT factor is K-ss tliaii unity. 'I'lie loss must Ik- ul)taiia'(i

by calculatinfi; /• li for tlic llnr, or, what amounts to the sjime thing,

by muhiplyinj^ the resistance-voUs by the current.

The r»'sistanee-vohs in this case are 307. S, an<l the current

l')("..2r) amperes. The lo.ss ij 307. S X l'j<i.2.j= IS. 1 K, W. The

{HTcentagc losti is

48. 1 ...,= Kj.I per cent.

250+4K.1 '

Therefore, for the j)rol>lem taken, tlie drop is IS. 7 per cent, an<l llie

losn is 10.1 percent. If the j)roblem Ik.- to find the size wire for a pvcn

tlrop, it must l)e solvetl l)y trial. A.ssume a size of wire anil calculate

the (ln)p; the result in coiujection with the table will show the direction

an<l extent of the chanf^e necess;irA' in the size of wire to pve the

re<|uire<l droj).

The etVect of the line reactance in increasinj; the drop .should l)e

note«l. If there were no reactance, the drop in the al)ove example

would l>e given by the point obtained in laying off on the chart the

resistance-E. M. F. (15.4) only. This point falls at 12.4 per (rnt,

and the drop in terms of the generator K. M. F. would be

12 4 = 11 per cent, instead ot IS. 7 percent.112.4

' *

Anvthini: therefore which will reduce reactance is desirable.

Reactance can be reduced in two ways. One of the.se is to

diminish the distance l)etween wires. The extent to which this can

Ih' carrinl is limited, in the case of a pole line, to the lea.st di.^tance at

which the wires are snU' from swinging together in the middle of the

span; in irisidi* wiring, liythe danger from lire. The other way of

reilncing reactance is to split the copj)cr up into a greater mimU'r t)f

circuits, and arrange the.se circuits so that there is no inductive inter-

arlion. Vnr instance, supjM)se that in the example work«l out alnAe,

two No. 3 wires were u.setl in.stead <if one No. wire, 'i'he :vsislanee-

volts would Im- pnictically tlu' .sjim«-, but the reactan<e-v«ilts wotdd Ik*

211le.ss in the nitio J X

"- ^

.03'), since each circuit would U-ar half the

current the No. circuit ihx's, and the constant for No. 3 wire !.>• .241,

instead of L'L'S— that for No. 0. The elT<'cl of .suUlividing the eop|H'r

i.s al.so shown if in tin' example given it is desinxl to retime the drop

59

50 ELECTRIC WIRING

to, say, one-half. Increasing the copper from No. to No. 0000 will

not produce the required result, for, although the resistance-volts will

be reduced one-half, the reactance-volts will be reduced only in the

ratio .212^ If, however, two inductively independent circuits of No.

.228*

wire be used, the resistance- and reactance-volts will both be reduced

one-half, and the drop will therefore be diminished the required

amount.

The component of drop due to reactance is best diminished by sub-

dividing the copper or by bringing the conductors closer together. It

is little affected by change in size of conductors.

An idea of the manner in which changes of power factor affect

drop is best gotten by an example. Assume distance of transmission,

distance between conductors E. M. F., and frequency, the same as in

the previous example. Assume the apparent power delivered the

same as before, and let it be constant, but let the power factor be given

several different values; the true power will therefore be a variable

depending upon the value of the power factor. Let the size of wire

be No. 0000. As the apparent power, and hence the current, is the

same as before, and the line resistance is one-half, the resistance-

E. M. F. will in this case be

15.4—^, or 7 . 7 per cent of the E. M. F. delivered.Li

Also, the reactance-E. M. F. will be

.212X17.8 ,. ^

228^

P^^ '

Combining these on the chart for a power factor of .4, and deducingthe drop, in per cent, of the generator E. M. F., the value obtained is

15.3 per cent; with a power factor of .8, the drop is 14 per cent;

with a power factor of unity, it is 8 per cenl. If in this example the

true power, instead of the apparent power, had been taken as constant,

it is evident that the values of drop w'ould have differed more widely,

since the current, and hence the resistance- and reactance-volts,

would have increased as the power factor diminished. The condition

taken more nearly represents that of practice.

If the line had resistance and no reactance, the several values

of drop, instead of 15.3, 14, and 8, would be 3.2, 5.7, and 7.2 percent respectively, showing that for a load of lamps the drop will not

60

ELEmUC WmiN'G 51

l>i> imicli iiKTrasiil l>y reactaiiii-; l)iit that with a li»ati, .siuh a.s iiithu--

tion inoturs, whosi' powrr factor is k-.ss than miity, niw .should Utaki'ii to kr<'|)

the rcactaiici' as low as practicahlt*. In all casivs it is

ailvisiihle to place conductors as close to<,'ether as gtKxl practice will

permit.

When there is a transformer in circuit, and it is desire<l to obtain

the conihine<l tlrop of transformer and line, it is necessarj' to know

the resistance- and reactance-volts of the transformer. The resist-

ance-volts of the combination of line and transfcjnner are the .sum of

the resistance-volts of the line and the resistance-volts of the trans-

fonner. Similarly, the reactance-volts of the line and transfonner

are the sum of their respective reactance-volts. The resistance- and

reactance-E. M. F.s of transformers may usually be obtaiiu'*! fn)m

the makers, and are ordinarily given in per cent.* The.M^- \ht-

centages expre-ss the values of the resi.stance- and reactance-E. M. F.'s

when the transformer delivers its normal /«//-/oaJ current; and they

express these values in terms of the normal no-luad E. M. V. of the

transformer.

Consider a transformer l)uilt for trans-formation Wtween 1,(KX)

and KK) volts. Suj)pose tlie resistance- and reactance-E. M. E.'s given

are 2 per cent and 7 per cent respectively. Then the corresjx)nding

voltages when the tninsformer delivers full-load current, are 2 and 7

volts or 20 and 70 volts according as the line whose droj) is re«|uireil

is connecte<l to the low-voltage or high-voltage terminals. These

values, 2—7 and 20—70, hold, no matter at what voltage the trans-

•Whcn the ro<iuirP«l vnliios cannot 1)0 olttaincvl from tho makers, thry may Ihj

iMf^oHurc*!. .McoMurt) tlir n^isiunccof Iwith nill.s. If the linoto Ih< rnlcuhiutl i» uitachMf

to th« lilKh-voltaKe tiTniinuls of thu traiisforiiicr, the .i .^ that of thi

hieh-viiHaKO roil. ;'/uj th)< rotlHtancc olxaineil l>y !» ' IhenitloofI:

' 'Ion the mra.Hiir<"<l r<»iislaii<'<' iif till' |o»-M>U.4Kt' ri.il I

' •

• of

tri Moil JH 10. ihe ctiulvalent r<'sisian(t> rrfcrrf"! to the li• It

III" r< r the hli;h-voltaKe roil, jtlut 100 tinieN that of (he I

e'liiU -.taiice niiiltlplUol liy the Mkti mi1Iii(;«« current t

r< si-.';nnf»-volt(i n-frrnxl t ' rfferrol to tlii< low-volluKe ein'iilt In 1 1.< .ni'c of Iho low-volt.i. .../xjlhalof lhi< hlKh voltak'i' eoll rtducrd in the w|uareof (he ratio uf (raiwformndon It follown.

of i-ourwv fnitn ttilx. (hat the valiH>Hof the r(«U(ane«>-vo|lH referr'-' ' ''•• tw<» rirrulla

hear to eaeh other the ratio of (ran.tformatlon To obtain the \ volla. itluirt-

rlrriili oni- roll of thi< tranAfonuer aii'I'

lhi< other roil ilN normal ciim'nl at i.

tln> n-iii iaiiii>Mi|i<i li In il,i-N II.. nauUaiililalni'<l In 'iin' I .,•• M iiM... ,r I.. •

i If a

rliMx valii- << (if iiH«

T9*\»tar\(t \

61

52 ELECTRIC WIRING

former is operated, since they depend only upon the strength of cur-

rent, providing it is of the normal frequency. If any other than the

full-load current is drawn from the transformer, the reactance- and

resistance-volts will be such a proportion of the values given above

as the current flowing is of the full-load current. It may be noted, in

passing, that when the resistance- and reactance-volts of a trans-

former are known, its regulation may be determined by making use

of the chart in the same way as for a line having resistance and

reactance.

As an illustration of the method of calculating the drop in a

line and transformer, and also of the use of table and chart m calculat-

ing low-voltage mains, the following example is given :

Problem. A single-phase induction motor is to be supplied with 20 am-

peres at 200 volts; alternations, 7,200 per minute; power factor, .78. The

distance from transformer to motor is 150 feet, and the line is No. 5 wire, 6

inches between centers of conductors. The transformer reduces in the ratio

——, has a capacity of 25 amperes at 200 volts, and, when delivering this

current and voltage, its resi?tance-E. M. F. is 2.5 per cent, its reactance-

E. M. F. 5 per cent. Find the drop.

The reactance of 1,000 feet of circuit consisting of two No. 5

wires, 6 inches apart, is .204. The reactance-volts therefore are

1 'lO

.204 X Y^ X 20 = .01 volts.

The resistance-volts are

.627 X -i^ X 20 = 1.88 volts.

1,000

At 25 amperes, the resistance-volts of the transformer are 2.5 per

20cent of 200, or 5 volts. At 20 amperes, they are — of this, or 4 volts.

Similarly, the transformer reactance-volts at 25 amperes are 10,

and at 20 amperes are 8 volts. The combined reactance-volts of

transformer and line are 8 + .61 = 8.61, w-hich is 4.3 per cent of

the 200 volts to be delivered. The combined resistance-volts are 1.88

+4, or 5.88, which is 2.94 per cent of the E. M. F. to be delivered.

Combining these quantities on the chart with a power factor of .78,

the drop is 5 per cent of the delivered E. M. F.,

or — = 4.8 per cent

of the impressed E. M. F. The transformer must be supplied with

62

ELECTRIC >VIRING r,3

^^^^ = 2,100 volts,.952

in onler that 200 volts shall he «h'livere«l to the inot«»r.

Tahle X (page 47) is made out for 7,200 alteriuitions, hut will

answer for any other nun>l)er if the values for n-aetanee be changed

in direct j)nij)ortion to the change in alternations. For instanc-e,

,.

, ,.

, 10,000for Ifi.iMM) alternations, multiply the reactances given by ^

i'lir uiher distances hetween centers of conductors, interpolate the

values triven in the tahlc. As the reactance values for diliVreiit sizes

of wire change by a constant amount, the tahle can, if desired, be

rea<lily extendetl for larger or smaller conductors.

The table is basetl on the assumption of sine currents and

E. M. r.'s. The Ix^st practice of to-day produces machines which

so closely approximate this condition that results obtaine<l by the

alxne metluHls ore well within the limits of practical re(|uirements.

Polyphase Circuits. So far, single-phase circuits only have

Int'ti dealt witii. A simple extension of the metluHls given al)ove

adapts them to the calculation of polyphase circuits. A four-wire

quarUr-phase (two-phase) transmission may, so far as loss and regida-

tion are concenietl, be replaced by two single-phase circuits identical

(as to size of wire, distance between wires, current, and E. M. F.)

with the two circuits of the quarter-pha.se transmission, providt^l that

in lK)th cases there is no inductive interaction Iwtween circuits. There-

fore, to calculate a four-wire, quarter-phase transmission, computethe single-phase circuit recpiirt^l

to tr.msmit one-half the jM)wer at

the same voltage. The <|Uar((T-j)hase transmission will require two

such circuits.

A three-wire, thrvc-phasc transmi.ssion, of which the conductors

are synnnetrically relalnl, may, .so far as lo.ss and n-gulation are

concernnl, be replace<l by two single-pha.se cin-uits having lU) in-

ductive interaction, and i«hMitical with (he three-phase line as to

size, wire, and distance In-tween wires. Thert-fore, to calculate a

three-|)hase Inmsini.ssion, calculate a single-phase- circuit to caiTj*

one-half the load at the s;iine vnliage. The thn'c-pha.se transmis-

sion will rc(iiiire three wiii-s of the si/«' and distance U-tween centers

as obtaine«l for the singl«--|)hase.

.\ three-wire. iw()-pha.sc transmi.ssion may U- cal«»iIaU\J

03

54 ELECTRIC WIRING

exactly as regards loss, and approximately as regards drop, in the

same way as for three-phase. It is possible to exactly calculate

the drop, but this involves a more complicated method than the

approximate one. The error by this approximate method is gen-

erally small. It is possible, also, to get a- somewhat less drop and

loss with the same copper by proportioning the cross-section of

the middle and outside wires of a three-wire, quarter-phase circuit

to the currents they carry, instead of using three wires of the same

size. The advantage, of course, is not great, and it will not be con-

sidered here.

WIRING AN OFFICE BUILDING

The building selected as a typical sample of a wiring installation

is that of an office building located in Washington, D. C. The figures

shown are reproductions of the plans actually used in installing the

work.

The building consists of a basement and ten stories. It is of

fireproof construction, having steel beams with terra-cotta flat arches.

The main walls are of brick and the partition walls of terra-cotta

blocks, finished with plaster. There is a space of approxnnately five

inches between the top of the iron beams and the top of the finished

floor, of which space about three inches was available for runningthe electric conduits. The flooring is of wood in the offices, but of

concrete, mosaic, or tile in the basement, halls, toilet-rooms,

etc.

The electric current supply is derived from the mains of the local

illuminating company, the mains being brought into the front of the

building and extending to a switchboard located near the center of the

basement.

As the building is a veiy substantial fireproof structure, the onlymethod of wiring considered was that in which the circuits would be

installed in iron conduits.

Electric Current Supply. The electric current sapply is direct

current, two-wire for power, and three-wire for lighting, having a

potential of 236 volts between the outside conductors, and 118 volts,

between the neutral and either outside conductor.

64

ELECTRIC \VIRL\G 65

SwitcliboarJ. ( )ii tlu- .switch hoanl in tlie hasement are mounted

wuttmottTs, pnividttl by tlie local t-lfctric connmiiy, aiul U»e various

switches re(|uire(l for tlic control ami iijHTatioii of the lighting and

power fetnlers. There ari- a total of tentri[jlc-j)ole switches for light-

ing, and eighteen for power. An indicating voltmeter and ann)eremeter are also placeil iti the .switchlxianl. .\ voltmeter is prcjvidtil

with a tlouhle-throw switch, and so arrangeil as to measure the jxjten-

tial acro.ss the two outside conductcjrs, or l>etween the neutnil con-

ductor and eitlier of the outside conduct(jrs. The ampere meter is

arningetl with two shunts, one being placeil in each outside leg; the

shunts are coimected with a double-pole, double-throw switch, so

that the ampere meter can be coimected to either shunt and thus

measure the current supplied on eac-h sitle of the system.

Character of Load. The building is occupie<l partly as a news-

paper office, and there are several large presses in atldition to the usual

linotype machines, trinuners, .shavers, cutters, saws, etc. There are

also electrically-driven e.\hau.st fans, house pumps, air-compressors,

etc. The upper portion of the liuilding is almost entirt^lv devoteil

to offices renteil to outside parties. The total mnnU-r of motors

su[)plit-<l was 55; and the total number of outlets, 1,100, sujiplving

2,4(M) incandescent lamps and 4 arc lamps.

Feeders and iMains. The arrangement of the various fee»lers

und mains, the cut-out centers, mains, etc., which they supplv, are.

.shown diagranunatically in Fig. 41, which also gives in scluHlule the

sizes of fee<lers, mains, and motor circuits, and the data relating to the

cut-out panels.

Although the current su|)ply was to be taken from an outside

.source, yet, inasmuch as there was a pn)bal)ility of aj)l;int l)eing in-

stidled in the building itself at some future time, the three-wiresv.stem

of feetlers and mains was designetl. with a neutnd conductor txjual

to the combined capa<'ity of the two outside conductors, .so that

lL'0-volt two-wire generators could b«- utili/ed without any change in

tlie feeder^.

r>a.scmcnt. Tlie plan of the l«isemcnt, Fig. 42, shows the branch

« ircuit wiring for the outlets in the Iwi.sement, and the hn-ation of the

main switchlnianl. It al.st) .shows the trunk cables for the intir-

cotmection .sy.stem .vning to provide the nec«'.s.sar}' wires for lelephone.s.

00

FCEDCRS

X ALL CONDUCTORS IN ONt CONDUIT.KX SEPARATE CONDUIT FOR EACH CONDUCTOR

M X X THIS FEEOEIR IS TO BE DIVIDED INTO FOUR (-*)~ CONDUCTORS OF»t 2000000 C-M. EACH.- EACH CONDUCTOR IS TO BE INSTALLED IN A SEP*- ABATE 3" (Inside oiam) conduit

LS^LIGHTING SUPPLYP-S.=POWER "

XKXX SEPARATE s'tTMSIDE DIAK^CONDUiT FOR EACH•• CONDUCTOR

in

<

KLECTRIC WIUIXG 57

rt<^

I u

1 i

P

SWITCHBOAF^C

i

-a-'

*^

i7

-Q -6"

nn

c^/~i-<F ni

58 ELECTRIC WIRING

tickers, messenger calls, etc., in all the rooms throughout the building,

as will be described later.

To avoid confusion, the feeders were not shown on the basement

plan, but were described in detail in the specification, and installed

in accordance with directions issued at the time of installation. The

electric current supply enters the building at the front, and a service

switch and cut-out are placed on the front wall. From this point, a

two-wire feeder for power and a three-wire feeder for lighting, are

nm to the main switchboard located near the center of the basement.

Owing to the size of the conduits required for these supply feeders, as

well as the main feeders extending to the upper floors of the building,

the said conduits are run exposed on substantial hangers suspended

from the basement ceiling.

First Floor. The rear portion of the building from the basement

through the first floor. Fig. 43, and including the mezzanine floor,

between the first and second floors, at the rear portion of the building

only, is utilized as a press room for several large and heavy, modern

newspaper presses. The motors and controllers for these presses are

located on the first floor. A separate feeder for each of these press

motors is run directly from the main switchboard to the motor con-

troller in each case. Empty conduits were provided, extending from

the controllers to the motor in each case, intended for the various

control wires installed by the contractor for the press equipments.

One-half of the front portion of the first floor is utilized as a news-

paper office; the remaining half, as a bank.

Second Floor. The rear portion of the second floor. Fig. 44, is

occupied as a composing and linotype room, and is illuminated chiefly

by means of drop-cords from outlets located over the linotype machines

and over the compositors' cases. Separate ^-horse-power motors

are provided for each linotype machine, the circuits for the same being

run underneath the floor.

Upper Floors. A typical plan (Fig. 45) is shown of the upper

floors, as they are similar in all respects with the exception of certain

changes in partitions, which are not material for the purpose of illus-

tration or for practical example. The circuit work is sufficiently

intelligible from the plan to require no further explanation.

Interconnection System. Fig. 46 is a diagram of the intercon-

nection system, showing the main interconnection box located in the

68

ELF.CTRIC WIHIN'G 59

T:^:

C

II „ I c_j^ j_

, L'^'?i%--^ ^-.^V*:

NO POINT X

r

SCHEDULE. «" CIRCUITS

p

^ JL-s:

._ i^.i..

fe-^^-^

^n-ai-i

€

tr~TjmJ v% ^

dz

ELECTRIC WTRIN'C; 61

r

r^^r ^..

I • ' - ^ ^ "Iz^^ Q-.-.-.-.-.j

<

^ r

4

r* *--=•'

?v0'

rOCR

i^l?^v?-ir^^-

-;-i

J«;-n c.-:

A '"IIs

.SHI

I'-::

>,; rt.-.-.-.-.-.-ri

I

V:-^'

In

r-^uLC oFORCurra1

—r-T"

mi

^

J

1 11^'. 4.1. Wlrlnu of nil (>••' •

Tyj)lral IMiiii of fpiMTFIoorH. Showing cinuli \s .<tc. All th<< FliHini nborell»< Scfouil ucn SliuUiir to oiiK Aiiiithcr In I';..,.. . ..i t. mly lii(°uiii|>.ira(tv<<ly

t'liliiiiMtruutt LHiiiillMuf I'uriliUmit.

71

— FIXTURES.—

ELK(n^i{i(: wiRiN'r; 03

lia.sfimiit; .idjuiiiiii;^ tliis inain Imjx is liicatttl tin- ti-riiiiiial Ihjx of llje

liwal tflt'jdioiif (-niii|)aiiy.A

.si'j>arato sysU'iii of fit-dc-rs is pmviiUil

ft»r tilt' tickt-r systcin, as tlii-se coiKluctDrs nijuire .vjiiiewluit liravier

insiiIatiDii, aii<l it was tlioii^lit iiiadvisalile to plare them in the same

coiuluits with the telephone wires, owing to tlie higher potential of

ticker circuits. A separate intcreonnection cahle nnis to each fl«K)r,

for telephone anil messenger call pui-jx)ses; and a central Ih)X i.s place<l

near the rising jK)int at each floor, from which nni subsidiarj' cables

to several i)<)ints svmmetricallv locatetl on the various flo<jrs. From

these sui)sidiar}' l)oxes, wires can he nm to the various ofHces ret|uiring

telej)hone or other service. Small pipes are provitled to ser\e as race-

ways from ofiice to ofKce, so as to avoid cutting partitions. In this

way, wires can he c|uickly proviiletl for any office in the building with-

out damaging the Iniilding in any way whatever; and, as provision is

made for a special wooden moukling near the ceiling to accommodate

these wires, they can Ix* run around the room without disfiguring the

walls. All the main cables and subsidiary- wires are connected with

special interconnection blocks numbered serially; and a schedule is

y)r(tvideil in the main interconnection box in the basement, which

enables anv wire originating thereat, to be readilv and convenientlv

traced throughout the Iniikling. All the main cables and subsidiarj*

cables are run in iron conduits.

OUTLET=BOXF:S, CUT-OUT PANELS, ANDOTHER ACCESSORIES

Outlct-Uoxcs. lU'fore the intr(xluction of iron conduits, outlet-

l)oxes were considercnl unnecess;int', and with a few extrptions were

not usiil, the conduits l>eing brought to the outlet and cut olT after the

walls and ceilings were plastered. With the intnKluction of iron con-

duits, however, the necessity for outlet-boxes was realizetl; and the

llulc.s of the Fire I'nderwri'ers were nuHlilit>tl so as to re<|uin' their use.

The Riiltn of the Xatlifiial KUriric CrnU- lutw rt'«|uin' outlet-lx)Xes to

Im- ust-d with rigid irmi and flexible steel conduits, and with annontl

cables. A p<jrtion of the rule reijuiring their use is as follows:

All interior roiuluitH nml iiniion'<l calili'.s "ruust 1k> <>(|uip|M>ii nt everyiijllot with !in iipprnvi'M oullot-l)ox nr pinlf.

"Oiitlft-pliitcN iiiUHt not l>o uw(l \vlicn> it in |)ritcli(-»l>lo to itiHtall uiitlet-

I1UXC8.

73

64 ELECTRIC WIRING

"In buildings already constructed, where the conditions are such that

neither outlet-box nor plate can be installed, these appUancesmay be omitted

by special permission of the inspection department having jurisdiction, pro

viding the conduit ends are bushed and secured."

Fig. 47 shows a t}^ical form of outlet-box for bracket or ceiling

outlets of the universal ti/pe. \^Tien it is desired to make an openingfor the conduits, a blow from a hammer

will remove any of the weakened portion

of the wall of the outlet-box, as may be re-

quired. This form of outlet-box is fre-

quently referred to as the knock-out type.

Other forms of outlet-boxes are made with

the openings cast in the box at the re-

quired points, this class being usually

stronger and better made than the univer-

sal tj'pe.The advantages of the universal

type of outlet-box are that one form of box will serv^e for any ordinary

conditions, the openings being made according to the number of

conduits and the directions in which they enter the box.

Fig. 48 shows a waterproof form of outlet-box used out of doors,

or in other places where the conditions require the use of a water-

tight and waterproof outlet-box.

It will be seen in this case, that the box is threaded for the con-

WOOPTPig. 47. Universal andKnocl^-Out Type of

Outlet Box.

TFig. 48. VVater-Tight Outlet Box.

Courtesy of E. Krantz Manufacturing Co., Brooklyn, N. 1 .

duits, and that the cover is screwed on tightly and a flange provided

for a rubber gasket.

74

•'IT/A.^DONCOUUMNA R^.^

N'DC-. :...• I XKna AHOtTTBCXJ-

OOO- IT" 3T- WMMUCTOM DC-

-)_4-4-j4''-1'M-'M''t- i^^'*"

FIRST-FLOOH PLAN OF HOUSK FOR tllAS. A. UUUULA.S. tsy.. W AMI INu I U.N.

I'rlni-llnl K""ln'i i;i i'li-I :.f 'i- .11 Ii;

. li

'

MnrtllllK K<">lll." I.O'

Tliriiwii I>jH'ri. I'rr>vlili'

(It) I•

Ihrm '"

;r- . r 1*;\'! ' ^r:l^•^ I Iv'v.- t!

LI, L.

ELFXTUIC WUilNf; 65

Figs. 49 and 50 sh(i\v water-tij;ht llt^»r lx)xes which are for outlets

IiKiiteti in the Hikjf. N\ hile the nile.s<h) not reijnire that the HiH*r outlet-

Ik)X shall l>e \vater-tij,'ht, it is stron^'ly reetmiinentUil that a water-

titrht outlet l)e use«l in all rases for floor coiuieetions. In this ejise

also, the coiuluit ojR'niiif^is threadeil, as well as the stem et)ver throujjh

which the extension is made in the conduit to the desk or table. ^^ hen

the tl(M)r outlet cDiuiection is not re(|uired, the stem cover may In;

removed ami a flat, blank cover be use<l to replace the same.

A form of (jutlet-l)ox useil for flexible steel cables an«l steel ar-

mored cable, has already l>een shown (see Fi^. o).

There is hardly any limit to the numlx'r and variety of makes of

outlet-lK>xes on the market, ada|)te«l f<jr onlinary and for sjH'cial con-

Klg. 4». FlK. 50.

Types of Floor Outlet-Boxes.

ditions; l)ut the t^-pes illustrate<l in these pages are char.ideristic and

typical forms.

lUishiuKS. The Rules of the Xatitmal Electric Cixlc re«juire that

conduits entering jimction-lM)xes, outlet-lK)xes, or cut-out cabinets.,

.shall be provide«l with apj)ruvcd hu.shing.f, fitttil to j)n»tect the wire

from abnisittn.

Fig. ol shows a ty|)ical form of cuuduit bushing. This bushing

is screwjtl on the v\u\ of the conduit after the latter has Ui-n intro-

ducnl into the outlct-l)ox. cut-out cabinet, etc., tluTeby forming an

insulated orilice tojirolcc

t liic win- at (Ih- point where it leaves the

ciiud\iits, and to |>nvcii( .ibnision, grounds, slu)rt cin-uits, etc. Alo< k-mit ( Fig. 52) is .scn-wj-tl on the threadtxl end of tin- conduit U-fore

ihr (i)iiduit is placetl in llic outlet-lMix or cut-out cabinet, and this

l(Mk-niil iiiid bu.shing clamp the conduit >ccuiily in jxisition. Fig.

7 a

66 ELECTRIC WIRING

Pig. 51. Conduit Bushing.

53 shows a terminal bushing for panel-boxes used for flexible steei

conduit or armored cable.

The Rides of the National Electric Code require that the metal

of conduits shall be permanently and effectually grounded, so as to

insure a positive

connection for

grounds or leak-

ing currents, and

in order to pro-

vide a path of

least resistance

to prevent the

current from

finding a path

through any source which might cause a fire. At outlet-boxes, the

conduits and gaspipes must be fastened in such a manner as to

insure good electrical connection; and at centers of distribution,

the conduits should be joined by suitable bond

wires, preferably of copper, the said bond wires

being connected to the metal structure of the

building, or, in case of a building not having

an iron or steel structure, being grounded in a

permanent manner to water or gas piping.

Fuse-Boxes, Cut-Out Panels, etc. From the ver}' outset, the

necessity was apparent of having a protective device in circuit with

the conductor to protect it from overload, short circuits, etc. For

this purpose, a fusible

metal having a low

melting point was em-

ployed. The form of

this fuse has varied

greatly. Fig. 54 shows

a characteristic form

of what is known as

the link fuse with copper terminals, on which are stamped the ca-

pacity of the fuse.

The form of fuse used probably to a greater extent than any other,

although it is now being superseded by other more modem forms.

Fig. 52. Lock-Nut.

Fig. 53. Panel-Box Terminal Bushing.

Courtesy of Sprague Electric Co., New York, iV. J.

76

ELECnaC WIUIN'G Ch

Is tliat known as t\\v luli.son fiij<c-j)lu(/,.sliown in Fi^. '>'>. A |>or(fhiin

cut-out bliK-k usi-il witli tlu' I'Mison fuse is sliuwn in Fij^. '>().

Within the last four or five vears, a new form of fuse, known as

the cnclustd juse, has U't-n intrinhicetl anil used to a consitiemltle

Mg. M. Copper-TlppeU Fuse Lluk. Fig. 55. EUlHOn Fuse-Plug,

Courttsy oftlenfralEUftricVo. .Sehtntetadi). S. Y.

e.xteiit. A fu.se of this tyj)e is shown in Fij;. ".7. Fig. oS jcrives a sec--

tional view of this fu.se, showing tlie jjorous tilling .snrrouiKling the

fu.se-strijjs,and al.so the ileviee for indicating when the fuse has

Mown. This form of fuse is made with various kinds of terminals:

it can he use<l with s|)ring clips in small

sizes, and with a jKJst screw contact in

larger sizes. For oniinarA' low jH)tentials

.,^4^^ ^4 I ^ft^ftl '''''^ ^^''^^' '"^ desirahlc tor currents up to

(^^^F^P*' ^SF^^ aiiiiMifs;

hut it is a dchatahle (|ues-

tioii whether it is desiralile to use an en-

closed fuse for heavier currents. Fig. '»'.>

shows a cut-out ho.r with F^li.s»)n j)lug

fusc-hlocks usetl with knoh and tuU' wiring. It will l>e .seen that

there is no cfninection compartment in this fuse-l>ox, as the circuits

enter diR-ctly opj)osite the terminals with which they connect.

Fig. ()() .shows a cut-nut panel adaptinl for enclo-sinl fu.ses. and

mme

Flg.5«. Porcelain Cut-Out Block.

CourtttyufiitnfralKUctricCo.,Hchtntctady, .V. }'.

^ ® yJ

Klg. 57. KuiioMHl iir

installetl in a cal)-

inet having a <iiii-

nection t()m|)art-

ineiit. As will l>r

Men frr)m the <iil.

the tal.let itself is

.surrounde«| on the

four .sides by .slate,

which is .securetl in the corners l>y aIlgle-iI•^>n^. The outer Ih»x mayIm- fpf woimI hned with sln'et imn, i>r it may In- of in>n. Fig. (»!

sliows u door and trim fur a caliiinl nf thisty|M-.

It will U- Mfii that

11*;. ^- 1,11'

77

68 ELECTRIC WIRING

the door opens only on the center panel, and that the trim covers and

conceals the connection compartment. The inner side of the door

should be lined with slate, and the inner side of the trim should be

lined with sheet iron. Fig. 62 shows a sectional view of the cabinet

and panel. In this type of cabinet, the conduits may enter at any

point, the wires being

run to the proper con-

nectors in the connection

compartment.

Figs. 63 and 64 illus-

trate a type of panel-

board and cabinet hav-

ing a push-button switch

connected with each

branch circuit and so

arranged that the cut-

out panel itself may be

enclosed bv locked doors,

and access to the switches

may be obtained throughtwo separate doors pro-

vided with latches only.

This type of panel was arranged and designed by the author of this

instruction paper.

OVERHEAD LINEWORKThe advantages of overhead linework as compared with under-

ground linework are that it is much less expensive; it is more readily

and more quickly installed;and it can be more readily inspected and

repaired.

Its principal disadvantages are that it is not so permanent as

underground linework; it is more easily deranged; and it is more

unsightly.

For large cities, and in congested districts, overhead linework

should not be used. However, the question of first cost, the questionof permanence, and the municipal regulations, are usually the factors

which determine whether o^'erhead or underground linework shall

be used.

Fig. 59. Porcelaiu Cut-Outs in Wooden Box.

Courtesy of II. T. Paisle Co., Philadelphia, Pa.

78

ELECTRIC mnixG m

Tlu' principal factors to \)v foiisi<lcn'<l in (ivt'rlica<l linework will

\h: hriefly oiitliiutl.

Placing ot I'olcs. As a ^jt'neral rule, the jxilcs should l>c set fnjin

1(K) to 12') feet apart, which is «-(|uivaleiitto 'I'A to 12

)M)les |>er mile.

I'luler certain conilitions, these spaciiij^s given will have to Ije niolifieil;

hut if the |)oles are spacetl too far apart, there is danger of Uhj great

a strain on the |mi1cs themselves, jinil on the eross-arnis, pins, and

iL "^^^ "^ «-*'

70 ELECTRIC WIRING

Poles. Poles should be of selected quality of chestnut or cedar,

and should be sound and free from cracks, knots, or other flaws.

Experience has proven that chestnut and cedar poles are the most

durable and best fitted for linework. If neither chestnut nor cedar

poles can be obtained, northern pine may be used, and even other

timber in localities where these poles cannot be obtained; but it is

found that the other woods do not last so long as those mentionedj

Pig. 63. Cnt-Ont Pane! with Pnsb-Bntton Switches. Cover Removed.

and some of the other woods are not only less strong initially, but are

apt to rot much quicker at the "wind and water line"—that is, just

above and below the surface of the ground.

The proper height of pole to be used depends upon conditions.

In countn," and suburban districts, a pole of 25 to 30 feet is usually

of sufficient height, unless there are more than two or three cross-arms

required. In more densely populated districts and in cities where a

great number of cross-arms are required, the poles may have to be

80

KLECTRIC WIllING 71

40 to 00 fet't, or even Ioii<:er. Of course, tlie loiij^er the|>ole,

the

greater tlu- |M)»il>ilityof its lireakiiij;; or lH-ii<liii<;; and as the lenfi;:th

increases, the diameter of the butt end of jxile sliould also increase.

Tiil.lcXI -^ives the averajje diameters re<|uire«l for various heif^hts of

iM>les, and tlie «U'l)ththe poles should 1m- placeil in thegntund. Thes*

data have heen conipilnl from a numlier of standanl s|>ecili(a<ions.

TABLI-. XI

Pole Data

72 ELECTRIC WIRING

Before any poles are erected, they should be closely inspected for

flaws and for crookedness or too great departure from a straight line.

Where appearance is of considerable importance, octagonal poles

may be used, although these cost considerably more than round poles.

Gains or notches for the cross-arms should be cut in the poles before

they are erected, and should be cut square with the axis of the pole,

and so that the cross-arms will fit snugly and tightly within the space

thus provided. These gains should be not less than 4| inches wide,

m*i*rM!^'

Fig. 64. Cul-Out Panel with Push-Button Switcties. With Cover.

nor less than ^ inch deep. Gains should not be placed closer than 24

inches between centers, and the top gains should be at least 9 inches

from the apex of the pole.

Pole Guying. Where poles are subject to peculiar strains due

to unusual stress of the wires, such as at corners, etc., guys should be

employed to counteract the strain and to prevent the pole from being

bent and finally broken, or from being pulled from its proper ppsition.

82

EILRCTklC BliLL WIRING.

Ill wiriiit^ fur flec-tric Itells to In- ojxrnti'd liy Imtteiies, the

ilanger of causing tires from short circuits or poor contacts does

not exist as in tbe case of wiring for light and power, Ix'cause the

current strengtli is so small. Neither is the bell-titter reB[K)n6ible

to city inspectors or lire underwriters. On this account, Ixdl

fitting is too often done in a careless and slovenly manner, caus-

ing the a|i[»aratU3 to give unsatisfactory results and to require

frtMjUeiit rej»airs,so that the

e.\{)enseand inconvenience in the end

far more than offset any time saved by doing an inferior grade of

work. Hence, at the outset it is well to state that as much care

should be taken in the matter of joints and insulation of bell

wiring as in wiring for light or power.If properly installed, the electric bell forms a reliable and yet

inexjtensive means of signaling, and is far superior to any other.

< >n this account practically every new building is titted through-nut with electric bells.

In addition to the necessity of tliorouirhness ahvatly men-

tioned, care should be taken to use only reliable ap])aratus which

must be installed in accordance with the fundamentalj)rinciples

on which its satisfactory operation ilejuMids.

\MRi:.

The common sizes of wire in use for bell wor^ are Xos.

Is, 20, and 22. In general, however. No, 20 will be ound satis-

factory as it is usually sutliciently large, while in miny cases No.

22 is not strong enough from .-i mechanical standpoint.It is impcrtant that the wires should be well insulateu to

jire

_r «.m^m%m^^w. ^^w. iiw. <i.m.m.«.m. ;

vent accidental contacts with tlu< staples or other wires. Kirst of

all the wire slinuld !»«< tinne<|, as this |)revents the coj)|ht from

JM'ing aefini U|M>n by 'he sulphur in the insulation. It also facil-

ilate.4 Hol I. Ting. The iuuer coating of insulutiou should bo of

H.M

74 ELECTRIC BELL WIRING

India rubber, surrounded by several longitudinal strands of cotton,

outside of which are wound several strands of colored cotton laid

on spirally.This is next immersed in melted paraffin wax and

polished by friction. A short length of approved electric bell wire

is shown in Fig. 1.

"When ordering wire, it is well to have it furnished in several

different colors as this greatly facilitates both the original instal-

lation and later repairs, because in this way one line may be dis-

tinguished from another, taps from main lines, etc. Moreover, a

faulty wire having been found, it is possible to identify it at anydesired section of its length.

METHODS OF WIRING.

In running wires, the shortest and most direct route should,

of course, be taken between the battery, bells, and bell pushes.

There are two cases to be considered. The better method is that

in which the wires are run before the building is completed, and

the wiring should be done as soon as the roof is on and the walls

are up. In this case the wires are usually run in zinc tubes

secured to the walls with nails. The tubes should be from § inch

to ^ inch in diameter, preferablythe latter. It is better to placethe wires and tubes simultane-

^ ously, but the tubes may be putin place first and the wires drawn

in afterward, although this latter

1

Fig. 2.

^

plan has the objection that the insulation is liable to become

abraded when the wires are drawn in. In joining up two lengthsof tube, the end of one piece should be opened up with the pliers

so that it may receive the end of the other tube, which should also

be opened up, but to a less extent, to prevent wear upon the

insulation. Specially prepared paper tubes are sometimes substi-

tuted for the zinc.

If the building is completed before the wiring is done, the

concealed method described above cannot be used, and it is neces-

sary to run the wires along the walls supported by staples, where

they will be least conspicuous. Fig. 2 shows ordinary double-

pointed tacks, Fig. 3 shows an insulating saddle staple which

84

F.LECriilC liKLL W IKING iii

1

kFig. 3.

is to \)e recoiniueiidftl. Two wires ehould nevtT he secured under

the same staple if it eanjKissihly

la* avoided, owing to the dangerof short circuits. "With ii littUi

care it is usually po.ssihle to con-

ceal tile wiring l)i>hind the picture

mouldini', al(»n<f the skirting-iniard,

and iK'side the doorj)Osts

hut whi-rc

it is iinpossihh' to conceal it, a light

ornamental casing to match the

tinish of the room, may ho used.

It is sometimes advisahle to use

twin wires or two insulated win-s run in the same outer covering.In some cases it is well to run the wires under the iKtors,

laving them in notches in the tops of the joists or in holfs hored

ahout two inclu'S helow thetoj)3

of the joists.

JOtNTS.

AVlien making a joint, cari' should he taken to have a firm,

(•If.iii connection, lioth mechanically and electrically, and this must

always he soldered to j)reveMt corrosion. The insulation should

Ih* strij»pedoff the ends (tf llie wires to he joined, for a distance of

ahout 2 inches, and the wires made hright hy scraping oi sandpa-

E ^^zz^z^̂ yVv'. 1.

nering. They should tlu-n Im- twisted tiirlitly and evenly toir^tlier

iifl shown in Fi*'. 4.

Me.xt comes the ojieration of soldcriiiR, wliieh is ahsolutely

necessary if a jK-rmanent joint froni an »'leetrical stand|H)int is to

Iri ohtained. A jdint made without st)liler may he electrically

soun<l at tirst, hut its resistancerajiiilly iiiereas<'s, din< to deteri-

onition of the joint. As has already het-n stated, the wires should

Im- mad(4 hright and clean hefore they are twisted together.

Soldering (luids HJiould never he used, he<-ause tlH'V cause corrosiiMi

of the wire. The hest llux to tise is resin or com|M»site candle.

The soldering should always Im' done with aeiip|K'r

hit rather than

with aljIowpijM<

oi wirenuin's torch.

H&


A convenient form of soldering tool consists of a small copperbit having a semicircular notch near the end. • This bit should, of

course, be well tinned. It is then heated over a spirit lamp, or

wireman's torch, and the notch filled with soft solder. Lay the

joint, which has previously been treated with the flux, in this

notch and turn it so that the solder runs completely around amongthe spirals of the joint. The loose solder should be shaken off or

removed with a bit of rag. When the joint is set, it should be

insulated with rubber tape, so that it will be protected as perfectlyas the other portions.

It is often possible to save a considerable length of wire and

amount of labor by using a ground return, which, if properly

arranged, will give very satisfactory results, although a completemetallic circuit is always to be preferred. Where water or gas

mains are available, a good ground may be ob-

tained by connecting to them, being sure to

have a good connection. This may be se-

cured by scraping a portion of the pipe

perfectly bright and clean and then windingthis with bare wire; the whole is then well

soldered. An end should be left to which

the wire from the bell circuit is twisted and

/'--^ r-h/|-|

soldered. If such mains are not available,

V—I

J 1/ a good ground can be obtained by connecting~the wire from the bell circuit, as described

above, to a pump pipe. In the absence of

water and gas mains, and of a pump pipe,

a ground may be obtained by burying beneath

permanent moisture level a sheet of copper

or lead, having at least five square feet of siirface, to which the

return wire is connected. The ground plate should be covered

with coke nearly to the surface; the hole should then be filled in

with ordinary soil well rammed.

OUTFIT.

The three essential parts of the electric bell outfit are the bell

piish,which furnishes a means of opening and closing the circuit

at will, the battery, which furnishes the current for operating the

-nny^nr^Fig. 5.

86

ELECTIilC BELL WIHING 77

l>ell, ami the bell itself. Before discussing the combiimtion of

these pieces of ap|«iratU3in thu complete circuit, let us take up

the individual parts in order.

A bell push is shown diafrrannnatically in Fi{^. ij. In this

illustration P is the j)ush button; when

this is presided uj)on it brincrs the point

of the sprincr S in contact with the nietul

strip K, thus closintr the circuit with wiiich

it is connected in series. Normally the

springs are separated as shown, and the

circuit is accordingly open.

Bell pushes are made in various de-

signs and styles, from the simple wooden

Ttush shown in Fig. (> to very elaborate and expensive articles.

Fig. 7 shows four cast bronze pushes of neat apj>earance and mod-

enitej)rife.

Batteries. Klectric bells are nearly always operated on the

ojK-ncircuit plan, and hence the battery used is generally of the

Fig. 6.

Fig. 7.

op<Micircuit tyjH',

such as the I^'danche cell, which in use<l very

largely except for heavy work. Tliis is n zinc-carlK)n cell in which

the excitant is sal-aminoniiic di.ssolved in water, rolarinition ia

preventtnl by jMToxid**of munganese, which gives up part of its

oxygen, combining with the hydrogen set free and fornuiig water.

H7


Dry Batteries are also frequently used for bell work, their

principal advantage being cleanliness, as they cannotspill. Dry

cells are really a modification of the Leclanche type, as they use

zinc and carbon platesand sal-ammoniac as the exciting agent.

The Burnley cell, which is one of the principal types of dry cell,

has an electrolyte composed of sal-ammoniac, chloride of zinc,

plaster, flour, and water. This compound when mixed is a semi-

liquid mass which quickly stiffens after being poured into the cup.

The depolarizing agent is peroxide of manganese, the same as is

used in the Leclanche cell, this being packed around the carbon

cylinder. The top of the cell is sealed

with bitumen or some similar substance.

For very heavy work the Edison -

Lalande and the Fuller types of cell are

best suited, while for closed circuit work

the gravity cell is most satisfactory.

Bell. It is a well-known fact that

if a current of electricity flows througha coil of wire wound on an iron core,

the core becomes matrnetized and is ca-

pable of attracting any magnetic sub-

stances to itself. The operation of the

electric bell, like that of so many other

pieces of electrical apparatus, depends

upon this fact. A diagrammatic repre-

sentation of an electric bell is shown in

Fig. 8, in which M is an electromagnet

composed of soft-iron cores on which are wound coils of insulated

wire. The armature is mounted upon a spring K, and carries a ham-

mer H at its end for striking the gong. On the back of the armature

is a spring which makes contact at D with the back stop T. The

action of the bell is as follows: "When the circuit is closed throughthe bell a current flows from terminal 1, around the coils of the

magnet, through the spring K and contact point D, through the

back stop T, to terminal 2. In flowing around the electromagnet the

current magnetizes its core, which consequently attracts the arma-

ture. This causes the hammer H to strike the gong. While in

tliis position the contact at D is broken, the current ceases to flow

Fig. 8.

88

ELECTKIC iJKLL WIKIMI

arouii«l the electroiiiaîu't ami the cort'S constHjuently lose their

attractive force. Tht* armature is then carrie<l hack to its original

position hv tlie8j)rini^ K, niakinj^ contact at I), and the process is

retHâtftl. The hammer will thus vihrate and the hell continue to

ring as long as the circuit is closed.

Thetvp«'

of hell descrihed ahove il fho one most commonlyused. Such hells are made in a great variety of

shajR-sand styles,

the prices varying accordingly. It is imj»ortant that platinum

tipsl»e furnished at the contact point I), Fig. S, to prevent cor-

rosioii. The hells on the market today are of two classes, the iron

hox hell and the wooden hox Indl. A hell of the wocnlen hoxtyjR'

is

shown ill I'ii'. '.), and a hiidier <rnidt« hi-ll of the iron frame skeleton

tyjKîs shown in Kig. 10. I'ells without cttvers should never U' use*!,

u-. du~t will sfttlo on the contacts and interfere with their action."

CIRCUITS.

Thepossihli"

coiiiliinatiiUis of tin- various parts into complete

ciriMiit4 !iir .m, varied that it would Ik' iinpossihh'to descriU? iheu*


all; in fact, almost every one is to a certain extent a special

problem. It is, however, possible to give typical circuits the

underlying principles of which can be applied successfully to any

particular case.

Fig. 11 shows a bell circuit in its simplest form, in which P

represents the push, B the bell, and C the battery; all connected

in series. The circuit is normally open at P, and hence no cur-

rent flows to exhaust the batteries.

When P is pressed, the circuit,

otherwise complete, is closed and

current passes through the bell

causing it to ring, as already ex-

plained. For instance, the push

might be located beside the front

door, the bell in the kitchen and the

battery in the cellar; the location depending on the results desired

and conditions to be met. The wire between P and C may, if

necessary, be dispensed with and connection made to ground at Gand G, as shown by the dotted lines.

Fig. 12 shows an arrangement by means of which one bell B

^=^G

Fig. 11.

^G

P P"HI -^

Fig. 12. Fig. 13.

may be controlled by either of the pushes P or P'. This system

may be extended to any number of pushes similarly connected,

A method for ringing two bells simultaneously from one pushis shown in Fig. 13, where both bells B and B' will ring from pushP. Bells, if connected in this manner, should have as nearly as

possible the same resistance, otherwise the bell of lower resistance

will take so much current that there will not be a sufficient amount

left for the other. Also, the batteries must be of greater current

capacity as the amount of current taken is, of course, doubled. This

system can be extended to any number of bells connected in this

way, up to the limit of capacity of the battery to ring them. Figs.

90

v-s*t**"^

SIMPLE COMBINATION GAS AND ELECTRIC FIXTURE IN A DINING ROOM

<

< -z.

3 •-

^" u

<

-J ^•

00*

< a^- i

O •

o

^.

3

KLKCl Kl(• tUAA, W HUNG 81

12 and 13 inay Ih< foiubined bo that two or more hells may Ih>

ruiit^ from any one of two or more pushes.In ¥\ir. 14 is shown a scheme for ringin«^ eitlier Ih'II, li or li',

from one push anil one hattery l»ymeans of the two-point switch

re wi

I'iK. II.

S. "When the arm (jf the switch is on contact 1, thejiush will

riniT Ih'II li, and when on contact 2 it will riiij^ hell W.

In Fii;. 15 is shown a method of connectini; hells in series so

that li unci li' may be runn from J\ If all the bells so coniiecteU

were of the vihrating type, they would not work satisfactorily, as

it would he impossihle to time them so that the vihrations would

keep step, hence only one hell should

l)e of the vihrating type, and the others

should have the circuit hreakers short-

circuited, the vihratiuii hell servinir as

interruj»ter for the whole series. Ohvi-

ouslv this system re<juire3 a hii^her volt-

age than parallel connection, ami tlic

cells must 111- of sullicient ll.M.l'. to

ring the hells satisfactorily. Several

Ik'IIs may he connecleil in this way, if <

desired, up Id the limii (»f voltage of the"^

hattery. l"lk'- >'••

Oftentimes a Iwll is to U- rung from several dilTen-nt

For iiistanee, the Im-II in an e'evator nuiy ht* rung from any

places,

one uf

\)l

S2 ELECTRIC BELL WIRING

several floors, or the bell in the office of a hotel may be rung from

any one of several different rooms. In this case it is neoessary to

have some device to indicate from which push the bell was rung.The annunciator furnishes this information very well. A three-

station annunciator is shown in Fig. 16. The connections for an

annunciator are shown in Fig. 17 where tV represents the anun-

(••iator, li the bell, C thd battery, and P', P", and P^ the pushes.I or instance, when P' is pressed, the current passes through the

electromagnet controlling point 1 on the annunciator which causes

13 pfe

I

B

Fig. 17.

i

the arrow to be turned and at tlie same time the bell rings. After

tlie attendant has noted tlie siu;iial, tlie arrow is restored to its

no iiiul position by pressing a lever on tlie bottom of the annun-

ciator box.

The electric burglar alarm furnishes a very efficient protec-

tion and is an application of the principles already described. Tlie

circuit, instead of being completed by a push, is completed bycontacts placed on the doors or windows so that the opening of

either will cause the bell to ring. The same device may be used

on money-drawers, safes, etc.

In the case of the electric fire alarm, the signal may be giveneither automatically when the temperature reaches a certain degree,

or pushes may be placed in convenient' locations to be operated

manually. The pushes should be protected by glass so that theywill not be tampered with, it being necessary to break the glass

to give the alarm.

02

LIVING ROOM IN RESIDENCE OF J. R. CRAVATH, CHICAGO. ILL.

A good Arrangement for Reading and General Lighting in a Small Hoom.

ELECTRIC LIGHTING

HISTORN AM) I)11\HL()I>M1:M

Tlu- liistorv of (Icitric li^'litint; as a coniincrfial proposition In^gins

^villl the invfiitinii of the (inimiiic dyiiaino, liv Z. J. (irainiiif, in

1n7U, tuiiftluT with thi- iiitrothictioii of thi* Jaltlochkoir caiuilf or

li^'ht,which was first aniiouiict'd to tlif ptil)nc-

in 1870, and which

formed a feature of tlie International Exposition at Paris in 1S7S,

rp to this time, the eh-ctric hjjht was known to hut few investipitors,

one of tlie earliest l)ein<j Sir Iluinphrev Daw who, in IMO, pnHluctd

the first arc of any jjreat maj^nitudc. It was then called the voltaic

arc, and resulted from the use of two wood charcoal pencils as elec-

trtnles and a powerful battery of voltaic cells as a source of current.

From IMO to 1S.")9, many j)atents were taken out on arc lamps,

most of them oj)erated hy clockwork, hut these were not successful,

due chiefly to the lack of a suitahle source of current, since all de-

jH-nded on i)rimary cells for their ])ower. The interest in this form

oflij,'ht

died down about 1S')0, and nothing; further was attempted

until the advent of the (iramme dynamo.The incandescent lanij) was but a piece of laboratory apparatus

up to 1S7S, at which time Kdison produced a lamp usinfr a platiinim

spiral in a vacuum, as a source of Iij,'ht,the platinum beinj,' rendered

incandescent by the passage of an electric current through it. The

first successful carbon hlament was made in 1S70, this filament being

form«'d from strips of bamboo. The names of Kdison and Swan are

intimately coimecfcd with these early experiments.

From this time on, the dcvrlopmciit of electric lighting has Ihh-u

Verv rapid, and tin- consumption of incandescent lamps alone has

r<ii( ill d several millions t-ach year. When we compare the small

amount of lighting done by means of i-lectricity tw«'nty-five years ago

uiih the enormmis extent of lighting systems and the numerous

a|>pli<afions of electric illumination as they an* to-^lay, the growth

and t|evelopm«-nt of the art is se«'n to Iw very great, and the valu«- of

a *tu«ly of this subject may Im- readily appreciat«tl.While in many

Coj/fright, imto, b^ Amtrican ScAool qf CorruponJtnct.

on

ELECTRIC LIGHTING

cases electricity is not the cheapest source of power for ilhimination,

its admirable qualities and convenience of operation make it by far

the most desirable.

CLASSIFICATION

The subject of electric lighting may be classified as follows:

1. The type of lamps used.

2. The methods of distributing power to the lamps.3. The use made of the light, or its application.4. Photometry and lamp testing.

The types of lamps used may be subdivided into:

1. Incandescent lamps: Carbon, metallic filament, Nernst.

2. Special lamps: Exhausted bulb without filament, such as the Cooper-Hewitt lamp and Moore tube lamp.

3. Arc lamps: Ordinary carbon, flaming arc.

INCANDESCENT LAMPSThe incandescent lamp is by far the most common type of lamp

used, and the principle of its operation is as follows:

If a current / is sent through a conductor whose resistance is

R, for a time /, the conductor is heated, and the heat generated=

PR t, PR t representing joules or watt-seconds.

If the current, material, and conditions are so chosen that the

substance may be heated in this way until it gives out light, becomes

incandescent, and does not deteriorate too rapidly, we have an in-

candescent lamp. Carbon was the first successful material to be

chosen for this conductor and for ordinary lamps it is formed into a

small tlu-ead or filament. Very recently metallic filament lampshave been introduced commercially with great success but the carbon

incandescent lamp will continue to be used for some time, especially

in the low candle-power units operated at commercial voltages. Car-

bon is a successful material for two reasons:

L The material must be capable of standing a very high tem-

perature, 1,280° to 1,330° C, or even higher.

2. It must be a conductor of electricity with a fairly high re-

sistance.

Platinum was used in an early stage of the development, but,

as we shall see, its temperature cannot be maintained at a value high

enough to make the lamp as efficient as when carbon, or a metal

06

FM^' Tinr T.KJHTIXG

liii\ in;; a iiifltiii>; |)«>iiit liij^lirr than that «if{tiatiiiuiii, is us«-(|. Nearly

all attempts t«» sulistitutr aiiotlifr siihstaiK-e In phuv of <-arlMJH have

faih'tl until rrcently, and the fewlainj>.s

which are entirely c>r |)artia)ly

.successful will Im- treal»'<l later. The nature of the earhon eniployi-il

in incandescent lamps has, however, l»ei-n much improved ()Ver the

first forms, and owinj; to the still very j^reat imj>ortance of this lamp,

the nielliiid of niannfactiirc will l>e cuiisidcred.

A\anufacturc of Carbon Incandescent Lamps. J'n pardlitm vf

the rHiiiiuiit. (illidosc, a chemical compouml rich in carlM^n, is

prepared hy treating ahsorltent cotton with zinc chloride in pn»per

projjortions to form a uniform, <,a'latinc-like mass. It is customaryto stir this under a partial vacuum in order to remove huhhles of air

which mi^ht he contained in it and destroy its uniformity. This

material is then forced, "stjuirtetl,

"

through steel dies into alcohol, the

Fit;. 1. Fiirni.s of Filuniriit.s now in I'.so.

alcohol >cr\ in^' lu harden the soft, transparent thread>. Thi'sc threads

are then tiioroughly washed to remove all trace of the zinc chloride,

dried, cut to the desired lengths, wound on forms, and carbonized by

heating to a high temperature away from air. I )uring carbonization,

the cellulo.se is transformed into pure carbon, the volatile matt«T being

flriven off by the high temperature to which the Hlaments an- subjectitl.

The material becomes hard and stilV, assuming a permanent f»»rm,

shrinking in both length and diam«'tcr— the form being s|M'eially con-

structed so as to allow for this shrinkage. The forms an- made of

carbon blocks which are placed in |)luinbago crucibles and packedwith j)owden-d carbon. The crucibles, which are covjtimI with

l(M»sely fitting carbon covers, are gradually brought to a white heat,

at which tem|H-ratiire the cellulose is ehangeil to carlH)n, and then

allowed to iim>|. .Xficr cooling, the filaments are removeil, lueasund,

and insjM'cted, and the few jlcfcctive ones di.scardinl.

07

ELECTRIC LIGHTING

In the early days, these filaments were made of cardboard or

bamboo, and later, of thread treated with sulphuric acid.

A few of the shapes of filaments now in use are shown in Fig. 1,

the different shapes giving a slightly different distribution of light.

As here shown they are designated as follows: A, U-shaped; B,

single-curl; C, single-curl anchored; D, double-loop; E, double-

curl; F, double-curl anchored.

Mounting the Filament. After carbonization, the filaments

are mounted or joined to wires leading into the globe or bulb. These

wires are made of platinum—

platinum being the only substance, so

far as known, that expands and contracts the same as glass, with

change in temperature and which, at the same time, will not be melted

by the heat developed in the carbon. Since the bulb must remain

air-tight, a substance expanding at a different rate from the glass

cannot be used. Several methods of fastening the filament to the

leading in wires have been used, such as forming a socket in the end

of the wire, inserting the filament, and then squeezing the socket

tightly against the carbon; and the use of tiny bolts when cardboard

filaments were used; but the pasted joint is now used almost exclu-

sively. Finely powdered carbon is mixed with some adhesive com-

pound, such as molasses, and this mixture is used as a paste for fasten-

ing the carbon to the platinum. Later, when current is sent through

the joint, the volatile matter is driven off and only the carbon remains.

This makes a cheap and, at the same time, a very efficient joint.

Flashing. Filaments, prepared and mounted in the manner

just described, are fairly uniform in resistance, but it has been found

that their quality may be much improved and their resistance very

closely regulated by depositing a layer of carbon on the outside of the

filament by the process of fashing. By flashing is meant heating the

filament to a high temperature when immersed in a hydrocarbon gas,

such as gasoline vapor, under partial vacuum. Current is passed

through the filament in this process to accomplish the heating. Gas

is used, rather than a liquid, to prevent too heavy a deposit of the

carbon. Coal gas Is not recommended because the carbon, when

deposited from this, has a dull black appearance. The effects of

flashing are as follows:

1. The diameter of die filament is increased by the deposited

carbon and hence its resistance is decreased. The process must be

ds

FI.Kr'rUK I.KiHTING

(liscoiitimiftl u lii'ii tlit- cK-siri'il resistance is reueljed. Any little irrepi-

iarities in the filament will We eliminated since the smaller sections,

having the j;reater resistance, will l>ecome hotter than the remain<ler

of the filament anil the carlion is (Jeposited more rapitJIy at these

points.

2. The character of the surface is changed from a dull Mack

and c<)mj)arativcly soft nature to a Kright gray coating which is much

harder and which increases the life and efficiency of the filament.

Kxhauisi'uKj. After flashing, the filament is sealed in the bulb

and the air exhausted through the tube .1 in Fig. 2, which shows the

lamp in ditTereiit stages of its

manufacture. The exhaustion

is accomplished by means of

mechanical air pumps, sup-

j)lementcd by Sprenglc or mer-

cury j)umps and chemicals.

Since the degree of exhaustion

must be high, the bulb should

be heated during the process

so as to drive off any gas which

may cling to the glass. When

chemicals are used, as is now

almost universally the case, the

chemical is |)laccd in the tube

-1 and, when heated, serves

to take up much of the remain-

ing gas. Kxhaustion is neces-

sary for several reasons:Fin. DIIToreiit StuKCx III I'Uiiip Muiiufu<'iur(<.

1. To avoitl oxidization of thi- tilniiipnt.

2. To rcililcc the heat Cdiivcyi'il to tin- jtIoIm-.

3. To prevent wt-iir on tlir filament iliu- to ciirn-nts or ciMics in the cart.

After exhausting, the tubi- .1 is sealed olT and (lie lamp lom-

pIcUil for testing by attaching the base by means of plaster of I'jiri.s.

FJL'. < shows some of the forms of completed incandescvnt lamps.\ oltage anil Canillc-I'owcr. Incandescent lamps of the earlH)n

ty|M' vary in size finni the miniature l>att«ry and candelabra lamps to

those of .several humlrcd caiidlc-jiower. though flic lallcr are very

seldom used. The more common vjdues for the canillc-power are

»f>

ELECTRIC LIGHTING

8, 16, 25, 32, and 50, the choice of candle-power depending on the

use to be made of the lamp.The voltage will vary depending on the method of distribution

of the power. For what is known as parallel distribution, 110 or

220 volts are generally used. For the higher values of the voltage,

long and slender filaments must be used, if the candle-power is to be

low; and lamps of less than 16 candle-power for 220-volt circuits are

not practical, owing to difficulty in manufacture. For series dis-

tribution, a low voltage and higher current is used, hence the fila-

ments may be quite heavy. Battery lamps operate on from 4 to 24

volts, but the vast majority of lamps for general illumination are

operated at or about 110 volts.

Fig. 3. Several Forms of Completed I^amps.

Efficiency. By the efficiency of an incandescent lamp is meant

the power required at the lamp terminals per candle-power of light

given. Thus, if a lamp giving an average horizontal candle-powerof 16 consumes \ an ampere at 112 volts, the total number of watts

consumed will be 112 X \ = 56, and the watts per candle-powerwill be 56 ^ 16 = 3.5. The efficiency of such a lamp is said to be

3.5 watts per candle-power, or simply watts per candle. Watts

economy is sometimes used for efficiency.

The efficiency of a lamp depends on the temperature at which

the filament is run. In the ordinary lamp this temperature is between

1,280° and 1,330° C, and the curve in Fig. 4 shows the increase of

efficiency with the increase of temperature. The temperature attained

100

! TivTRir i.I(;htin(;

l)V a lilaiii. ..i ...jM-iitls

on tin- rati- at wliicli lii-at is nKHatt-d and the

amount of powir suj)|)li(il.Tlu- ratt- of ratliation of lu-at is pn)[Mjr-

tioual to tlu- art'a of the filaint-nt, tin* tltvaticjii in tinnHratiire, and

the emissivity of the surface.

Bv einis-sivity is meant the nuinlur of heat units <-mitte(l from

unit surface per (U'»jree rise in tcm[)<Tature al)ove that of surroundiiifj

Ixxlies. The hri<,'lit surface of a flaslied fihiment has a h)\ver emis-

sivitv than tlie (hill surface of an unhcatcd fihiment, hence U'ss

enerjjy is lost in licat railialioii and tin- cllicicncy of the filament is

increased.

As soon as incandescence is reached, the illumination increases

much more rapidly than the emission of heat, iience the increase in

1400

ELECTRIC IJGHTING

neighborhood of 800 hours. To obtain the most economical results,

such lamps should always be replaced at the end of their useful life.

In Table I are given values of efficiency and life of a 3.5-watt,

110-volt carbon lamp for various voltages impressed on the lamp.

These values are plotted in Fig. 5. The curves show that a 3%increase of voltage on the lamp reduces the life by one-half, while an

increase of 6% causes the useful life to fall to one-third its normal

value. The effect is even greater when 3.1-watt lamps are used, but

not so great with 4-watt lamps. From this we see that the regulation

of the voltage used on the system must be very good if high efficiency

lamps are to be used, and this regulation will determine the efficiency

of the lamp to be installed.

Selection of Lamps. Ordinary Carbon Type. Lamps taking 3.1

watts per candle-power will give satisfaction only when the regulation

of voltage is the best—practically a constant voltage maintained at the

normal voltage of the lamp.TABLE I

Effects of Change in Voltage

Standard 3. 5-Watt Lamp

Vo'.TAQE

Per Cent, of

Normal

FTF< lUIC LUiUriNG

«j

17C

I«c

151.

14C

13C-

ISO

IK

IOC

9C

8c

70-

6c

1-itr. Curves of Eniclciiry nnd I^ife o( Carlton Filunient Ihiiuph.

rt 1^1

I'lMI

Lamps of 4 walls per canclle-powiT should \>c installed wlu-n the

latioii is poor. Tlu-se valiU'S are for llO-volt lamps. A 22()-volt

|>sjiuuld have u lower efheiency to give a long life. This is on

FIk. fi. I.lfc Ciirvif) of Iiican(l<>w«Mit Ij>iii|m<.

account of the fait that, for the same candle-power, the 2'JO-volt lampmust he eoiistruete<l with a filament whi( h is long and shnder com-

pare<l to that of the 1 1()-vult lamp, and if such a filament is run at ti

iiigh tc-mperature its life is short. The 22()-volt lam|> is use<l to some

consi<|eral»l«' extent ahroad hut it is not em|)loy«-<l exti-nsively in the

United Stales. It is ciistonmry to oprrate such lamps at an eflieieney

of alMinl I watts |mt candle-power.

lo:l

10 ELECTRIC LIGHTING

Lamps should always be renewed at the end of their useful life,

this point being termed the smashing-point, as it is cheaper to replace

the lamp than to run it at the reduced candle-power. Some recom-

mend running these lamps at a higher voltage, but that means at a

reduced life, and it is not good practice to do this.

Fig. 7. Horizontal Distribution Curve for Single-Loop ril..n-.ei.t.

Fig. 6 shows the life curves of a series of incandescent lamps.

These curves show that there is an increase in the candle-power of

some of the lamps during the first 100 hours, followed by a period

during which the value is fairly constant, after which the light given

by the lamp is gradually reduced to about 80% of the initial candle-

power.

104

FT rrTRir lighting 11

Distributiun u\ lA^hl. In Vi}^. 1 arc .sliown various forins of

filamriit.s iisi-d in iiuaiMK-scrnt lamps, and Figs. 7 and 8 show the dis-

tribution oflij,'lit

from a sin|,'N'-l<M)[)filament of cylindrical cross-

section. Fij,'. 7 shows the distribution «)flij,'litin a horizontal plane, the

lamp l)cing mountetl in a vertical position, and Fig. 8 shows the dis-

oN(VI

FIr. S. Vcrllcul DiHlrllmtInn Purvc for SIiikIp-Ixhip Fllimirnt.

triljulion in a verticalpljin«'. By chaiipng the shape of the iilament

the light distrihution is varied. .\ mean of the reatlings taken in

till- horizontal |)lane forms the iiiftiii horizontal raiidli-jMnnr, and

this (•andle-pt)Wer rating is the «)ne generally assume<l f(»r tlu* «)nlinary

itnandesceiit lamp. .\ mean of the readings tak«'n in a verti<«l plane

gives us tin- mean vertical candle-power, init this value is of little use.

105


Mean Spherical CandIe=Power. When comparing lamps which

give an entirely different light distribution, the mean horizontal

candle-power does not form a proper basis for such comparison, and

the mean spherical or the mean hemispherical candle-power is used

instead. By mean spherical candle-power is meant a mean value of

the light taken in all directions. The methods for determining this

will be taken up under photometry. The mean hemispherical candle-

power has reference, usually, to the light given out below the horizon-

tal plane.

The Gem Metallized Filament Lamp. When the incandescent

lamp was first well established commercially, the useful life of a unit,

when operated at 3.1 watts per candle, was about 200 hours. The

improvements in the process of manufacture have been continuous

from that time until now, and the useful life of a lamp operated at

that efficiency to-day is in the neighborhood of 500 hours. Experi-ments in the treatment of the carbon filament have led to the intro-

duction of the gem metallized filament lamp. This lamp should not

be confused with the metallic filament lamps, to be described later,

because the material used is carbon, not a metal. As a result of

special treatment the carbon filament assumes many of the character-

istics of a metallic conductor, hence the term metallized filament.

The word graphitized has been proposed in place of metallized.

TABLE II

* Data on the Qem Metallized Filament Lamp

Watts

<i"I

^I

< <

CO

O i

Q<2O

o = -a

<

Q

o S,

rtflj

as

EOS

obh

bl(/}

1=)

oX

ooKC3Z

IS

u

o

aa

:3

<

<

tt

J-7.

c'_

3 e =cE - — a

^ i I--

s „• r <

s 5•"

=

cs :^ it"?

r -i -r M

111

-1

K it

3

EI.KCTUir T.KillTIW; 13

\Micii a tilaim-iit, as tn-ali-il in tlie onlinary iiiuniKr, is run at a

hi^li tfinpcratiiri- in a lani|) tlii-re i.s no iinpruveinent uf tlie iilaincnt,

hut it was «Jiscoveretl that, if thi- tn-atccl tihiiuents were suhj<-ctetl to

thr extrt-inily hiijh tfnijRTatnrc of tlie eh-etric resistanee furnatr—3,IMM) to .S,7(K) (lefj^rees C.—at atmospheric pressure, the physical

nature of the carlK)n was chanjjed and the n-suUinj; fihiinent coul«l Ije

operatcil at a higher tcinjH'ratiin- in the lamp ami a hi^'hcr efficiency,

to

i4 ELECTRIC LIGHTING

for the decrease in candle-power of the incandescent lamp. The

metallized filament lamp is operated at an efficiency of 2 5 watts pei

candle with a useful life of about 500 hours. The change in candle-

power with change in voltage is less than in the ordinary lamp on

account of the positive temperature coefficient of the filament. These

lamps are not manufactured for very low candle-powers, owing to the

difficulty of treating very slender fila-

ments, but they are made in sizes con-

suming from 40 to 250 watts. Table II

gives some useful information in connec-

tion with metallized filament lamps. The

filaments are made in a variety of shapes

and the distribution curves are usually

modified in practice by the use of shades

and reflectors. The general appearance

of the lamp does not differ from that of

the ordinary carbon lamp. Fig. 9 shows

typical distribution curves of the metallized

filament lamp as it is installed in practice.

Metallic Filament Lamps. The Tan-

talum Lamp. The first of the metallic

filament lamps to be introduced to any considerable extent com-

mercially was the tantalum lamp. Dr. Bolton of the Siemens &Halske Company first discovered the methods of obtaining the pure

metal tantalum. This metal is rendered ductile and drawn into

slender filaments for incandes-

cent lamps. Tantalum has a high

tensile strength and high melting

point, and tantalum filaments are

operated at temperatures much

higher than those used with the

carbon filament lamp. On ac-

count of the comparatively low

specific resistance of this material

the filaments for 110-volt lamps must be long and slender, and

this necessitates a special form of support. Figs. 10, 11, and 12

show some interesting views of the tantalum lamp and the fila-

ment. This lamp is operated at the efficiency of 2 watts per

Fig. 10. Round Bulb TantalumLamp.

Fig. 11. Tantalum Filament Before andAfter 1,000 Hours' Use.

108

ELFXTniC T.UillTINC 15

(aii(llr-|Mt\Vfr, witli a lift-(-iiiii|>aral)l<-

l.

Hy sjH'cial trratiiu-iit it is possiMc to iiHTt-asf tin* r«-sistaiicf of the

hhiiiH'iits so tliat tht'V iiiav Iw shortt-r and heavier than those used in

^J i H

FiB. 12.

AppciiniiK-c of Kiluinent After Filanioiit Knuiu' Sliowini;

lIuviiiK IJWMi L's«l. Ur«>ki'ii Klluiiiont.

the first of tlie taiitahini lamps. It should he noted that the life of

this type of lamp on alternatin<;-eurrent eireuits is somewhat uncer-

tain; it is mueh more satisfactory for operation on direct-<urreiit

circuits. 'I'ahles III and 1\' ^ive some "general data on the tantalum

lamp, an<l Ki;:s. !.'{ and 14 show typical distrihution curves for the

units as installed at |)resent.

TAiu.i; 111

Data III) lai)t;iliirn l.nmp

(iKNKUM- KI.KITIUC Ci i, MKTKS.

Sick or IIui.h

RrniTi.Aii Ui>rM>


T/vBLE IV

Data on the Life of a 25 =C. P. Unit

No. OF Hours Burned

IN « TUIC I-KHITING 17

to OIK' of tiiii<jstt II. A srcoiid iiiftlKxl foii'sist.s of the list- ofjMi\vtli-rf«l

tuiig-sti'iiand .somt- hiiuliiij; niatcrial, sonietiim-.s orpmit- and in otln-r

cases metallic. The powderctl tiiiijjsten is mixed with the hindinj^

iiiatiTJal, the paste stjuirtetl into fihiiiieiits, and the hindinjj material is

then expelled, usually \>y the aid of heat. Another metluxl <)f manu-

facturt consist.s of securinj.; tunijsten in colloiilal form, s(|uirtinf,' it

A^c'i A*0' JO ^PO" 10' O* /O* PO^ JO

so"

riK. U. Dl-Htriluitioii Curves for Tiuituliim I.i nip N". I. -lO Wuttji: No 2. sii Wniin

iiitii lilainents, and (ln'ii chan^'iii^ tlicni to the metallic formIty passinj^

electric current tlinni^'h the filaments.

The tungsten laiiip lias the highest eflicieiicy of any of the com-

mercial forms of nu'tallic filament lamps now in um-, ahout 1.2.') watts

|M'r candh'-|)ower when oju-rated so as to ijive a normal life, and lampsfor llO-volt service and consiiminj; hut l(( watts have re«>enlly Im-ch

put on the market. .\ 2.'»-watt lamp for this same volta^je ap|M'ars to

Im- a|»ossil)ility. The units intr<Hhiccd at first were of hi;;h candle-

power iH-caiise of the difliculty i>f manufacturing the slender lilanient."

required for the low candle-pow<-r lamps.

I 1 1


The advantages of these metals, tantakim and tungsten, for

incandescent lamps are in the improved efficiency of the lamps and

the good quality of the light, white or nearly white in both cases.

In either case the change in candle-power with change in voltage is

less than the corresponding change in an ordinary carbon lamp. The

disadvantage lies in the fact that the filaments must be made long and

slender, and hence are fragile, for low candle-power units to be used

Fig. 15. Multiple Tiingsten Lamp. Fig. 1 6. Series Tungsten Lamp.

on commercial voltages. In some cases tungsten lamps are con-

structed for lower voltages and are used on commercial circuits through

the agency of small step-down transformers. Improvements in the

process of manufacture of filaments and of the method of their sup-

port have resulted in the construction of 110-volt lamps for candle-

powers lower than was once thought possible. Figs. 15 and 16 show

the appearance of the tungsten lamp, and Figs. 17 and 18 give some

112

rilT'I-KK LK.IITINC; 10

tvpic-al(listriliiitioii »iir«»-.s. TaMfs \' and \'I pve daUi on this lamp

a-s it is nianufaclurfil at prt'sriit.( )ne very fonsicJeraMe applicatiuri

40'

FIk. 17. f. l". Distrilnition CurveR of 10()-Watt fien. Klecv TungstenIncandetK-ent I'liils with 11-3, r-3, and I)-3 Holophanew.

of tlie tungsten lamp is to incandescent street lif,'liting on series cir-

cuits, in which case the himp may l>e maile for a low voltajje across

its terminals and the filament mav l)e made comparativelv short and• I •

90*

BO'

70'

60'

^'»^• In. 1'i.mllf riiHor DlMrlluitloii (ilviMi wllh 10 r. p (ion. KIw. TiinRrtcii

SitIi-x Uiiiipiind Kiillal Wuvo 1{<>11«>< lor.

heavy. The tungsten lamp is also Ixiiig introduced as a low v<>l(age

I'.iitiry lamp.The .lust

laiMji,tin- /

laiuji.ihe ( )sram lan>p, the Ziri-«>n-W«»lfram

laiMp, tlu' Osmin lamp, etc.. are all tungsten lamps, the filamenls

heing prepand l»v sonjc of the gt'tieral methiMls alreatly ilescrilxd or

nKxIilicalions <>f iln-m.

20 ELECTRIC EIGHTING

TABLE V

Tungsten Lamps

MULTIPLE

Watts

KLEfTHir LKJIITIXG 21

TABLt VII

McltinK Point of Some Metals

Mir* 1.


ing process forming the filament or glower material of the lamp as

represented by the lower white line in Fig. 23. The more recent

glowers are made hollow instead of solid. The glowers are cut to

the desired length and platinum ter-

minals attached. The attachment

of these terminals to the glowers is

an important process in the manu-

facture of the lamp. The recent

discovery of additional oxides has

led to the construction of glowerswhich show a considerable gain in

efficiency over those previously used.

The glowers are heated to incan-

descence in open air, a vacuum not

being required.

As the glower is a non-conductor

when cold, some form of heater is

necessary to bring it up to a tem-

perature at which it will conduct.

Two forms of heater have been

used. One of them consists of a

porcelain tube shown just above

the glower, Fig. 23, about which a

fine platinum wire is wound; the

wire is in turn coated with a cement.

Two or more of these tubes are

mounted directly over the glower, or

glowers, and serve as a reflector

as well as a heater. The second

form of heater consists of a slender

rod of refractory material about

which a platinum wire is wound,the wire again being covered with

a cement. This rod is then formed into a spiral which surrounds the

glower in the vertical glower type, or is formed into the icafer heater,

Fig. 24, now universally employed in the Westinghouse Nernst lampwith horizontal glowers. The wafer heater is bent so that it can be

mounted with several sections parallel to the glower or glowers.

Fig. 20. Sectional View of MultipleGlower Westinghouse Nernst Lamp.

116

F.I.KrTlUr I.KiirilNr, 23

Thf lu'atiiij; (levicf i.s c-unnf<tc<l ut-ross tlit* circuit when the laiiip

is first tunu'(| on, and it must he cut out of circuit after the j;hjwt'rs

become con(luct<»rs in order to save the enerj;_v consuraetl l)V the

Fig. 21. Sectional Views of Single-iiluwer Wi-stlim'house Nenist Lamp.

heater ai.d to prolong the life of ihr licater. The automatic cul-out

is (jnerated hv means of an eh'ctroma;;net so arranfjcd that current

flows throujih this ma<,Miet as .soon as the j,'lower l)ecomes a conductor,

ami contacts in the heater circuit

are oi)cne(I l»y this ma<;nct. The

<-ontacts in the heater circuit are

kept normally closed, usually hy the

fupic uf gravity.

The conduclivily of the gjoucr

increa.se.s with the increase of (ciii-

perature— the material has a nega-

tive temperature coedicienl- hence

if it were used on a constant poten-

tial circuit tlircctly, the current

and lem|)erature woiihl contimic

to rise until the glower wa.s iU-

.stroyL'«l.T" prevent (he current llunifT.

11^


from increasing beyond the desired value, a ballast resistance is

used in series with the glower. As is well known, the resistance of

iron wire increases quite rapidly M^ith increase in temperature, and

the resistance of a fine pure iron wire

is so adjusted that the resistance of the

combined circuit of the glower and the

ballast becomes constant at the desired

temperature of the glower. The iron

wire must be protected from the air

to prevent oxidization and too rapid

temperature changes, and, for this

reason, it is mounted in a glass bulb

filled with hydrogen. Hydrogen has

been selected for tliis purpose because

Fig. 23. Westinghouse Nemst Screw it is an inert gas and conducts the heatBurner with Globe Removed, e j.u u ii j. x xi ii /• ^i

Showing Glower and^^"^ ^^^ ^^^11^^* to the Walls of the

Tubular Heater. bulb better than other gases which

might be used.

All of the parts enumerated, namely, glower, heater, cut-out, and

ballast, are mounted in a suitable manner; the smaller lamps have but

one glower and are arranged to fit in an incandescent lamp socket,

while the larger types are constructed at present with four glowers

—

i:r.ECTRIC LIGHTING 25

Tlu- injvantatjfs » laiiiHMl fur tlu- N'«rn>t lamp an-: Ili^'li tfli-

ciiiicv; a jjchmI color of li^'lit; a <,'o(k| distrihiitioii of li-;ljt without the

iisi- of rdifitoi • aloll-; life with low cost of iiiaiiitciiaiicf; ami a

eoiiij)li'te series i.«f sizes of units,

thus aliowiui; its a(la[ttioii to j)ra(-

tically all classes of illumination.

The lamj) is constructi'il for

Ixith tlirect- and alternatin;,'-curniit

service anil for 110 and 220 volts,

^^hcn the alternatinjj-currcnt lampis used on a 110-volt circuit a small

transformer, commonly called a

converter coil, Fig. 2o, is utilizi-d to

raise the volta<,'e at the lamp ter-

minals to ahout 220 volts.

Data on the Xernst lamp in its present form are piven in Table

^I1I, and Fif;s. 2() and 27 show the form of dislrihution curves.

TABLn Mil

General Data on the Nernst lamp

Fig. J5. CoiivertCT Coil.

Laui-

K .ITINO

l.s Wattb


given, approximately 3.1, 2.5, 2, L25, and L2 watts per candle respec-

tively. The figure of L2 watts per candle for the Nernst lamp is

based upon the mean hemispherical candle-power and it should not

be compared directly with the other efficiencies. The color of the

light in all of the above cases is suitable for the majority of classes of

illumination, the light from the higher efficiency units being some-

what whiter than that from the carbon lamp. All of these lamps are

constructed for commercial voltages and for either direct or alternating

current. The use of the tantalum lamp on alternating current is not

60' 75' SO' 75° 60'

Pig. 26. Distribution Curve of 132-Watt Type Westinghouse Nernst Lamp.Single Glower.

always to be recommended as the service is unsatisfactory in some

cases. The minimum size of units for 110 volts is about 4 candle-

power for the carbon lamp, 20 candle-power for the metallic filament

lamp, and 50 candle-power (mean hemispherical) for the Nernst

lamp. Some of the metallic filament lamps are constructed for a

consumption of as high as 250 watts, while the largest size of the

Nernst lamp uses 528 watts. The light distribution of any of the

units is subject to considerable variation through the agency of re-

flectors, but the Nernst lamp is ordinarily installed without a reflec-

120

i:t.I"( I'l:!*' iK.iiriN^; •_•:

tor. Tnu ti( allv all of tin- ullur miit-t (»f lii^li caiulli'-jxjwiT use- n-

Jlrctors aii<l oiilv a ft-w of tlu- typical curves of li^lit ilistrilMilioii <Mirv«-.s

with reflectors have Int'ii shown in connection with the ile.scri|>tion

of the lamps. The life of all of tin- coniinercial lamps i|escrilH*«l is

consiilere*! a.s .satisfactory. The mitiimitm life is seldom less than

')(H) hours and the iis<'ful lif«' is f,'enerally iHtween .'»(M) and I .(KKI hours.

On account of the slemlcr tilanunt.s einploynl in the metallic filament

60* 7p 9p 7p 60'

FIk'. -7. I>isirii>iitii)n of LiKht fnuu Multiple-Glower West In kIiou.sc Nornst I.anip!i »lih

8' (.'lear Globes. No. 1, 2 Glower: N'o. J, :5 Glower: No. .'!, 4 Glower.

lamj)s thev are not made for low canille-j>owcrs at commercial vol-

ta;,'«-s. The introduction of transformers for the purpose of chaiij^in^

the circuit voltafjc to one suitaMe for low candU'-power units has not

hecome at all general as yet in this country.

SPIXIAL LAMPSThe .Mcrcur_\ \apor I.amp. Tlic nnrcuiy va|>or lamp in this

country is|iiit

on llic market Itythe Cooper-Ilewitt l-'.lcctric Company

and it is lieiuf^' used to a considcralile extent for industrial illumination.

In this lamp mercury vapor, rendered iiicande.Mcnt hy the pas-sap-

of an electric curn-iit lhrouj,'h il. is the soun-e of light. In its stiindani

form lhi>. lamp consists of a long glass iul>c from which the air ha.s

l>een carefully exhausted, and which contains a sniall ain«>unt of

inelidlic UKTcury. The mercury is held in u large l»ull> at one end of

121


the tube and forms the negative electrode in the direct-current lamp.The other electrode is formed by an iron cup and the connections

between the lamp terminals and the electrodes are of platinum where

this connection passes through the glass. Fig. 28 gives the general

appearance of a standard lamp having the following specifications:

Total watts (110 volts, 3. .5 amperes)= 385

Candle-power (M. H. with reflector) = 700

Watts per candle = 0.55

Length of tube, total = 55 in.

Length of light-giving section = 45 in.

Diameter of tube = 1 in.

Height from lowest point of lamp to ceiling plate= 22 in.

For 220-volt service two lamps are connected in series.

The mercui-y vapor, at the start, may be formed in two ways:

First, the lamp may be tipped so that a stream of mercury makes

contact between the two elec-

trodes and mercury is vaporizedwhen the stream breaks. Second,

by means of a high inductance

and a quick break switch^ a very

i\igh voltage sufficient to pass a

current from one electrode to the

Fig. 28. Cooper-Hewitt Mercury Vapor j.i ii i xi• '

Lamp other through the vacuum, is m-

duced and the conducting vapor

is formed. The tilting method of starting is preferred and this

tilting is brought about automatically in the more recent types of

lamp Fig. 29 shows the connections for automatically starting two

lamps in series. A steadying resistance and reactance are connected

as shown in this figure.

The mercury vapor lamp is constructed in rather large units,

the 55-volt, 3.5-ampere lamp being the smallest standard size. The

color of the light emitted is objectionable for some purposes as there

is an entire absence of red rays and the light is practically monochro-

matic. The illumination from this type of lamp is excellent where

sharp contrast or minute detail is to be brought out, and this fact

has led to its introduction for such classes of lighting as silk mills and

cotton mills.' On account of its color the application of this lamp is

limited to the lighting of shops_, offices, and drafting rooms, or to dis-

122

LIBFniY KNl-IGHTKNINC. TMK WORI

.f I!

HI M'T VI W \ , I .i-.l III '

Hunt, wa<i I'niil fur l..ti

u; '.a: t II

ELFXTRIC T.ICIITINC 29

play windows wlit-re tlu* j;<km1s shown will not U- clian^if*! in a|i|M'ar-

anrc 1)V tlii" color of tin- li^jlit.It is ust'«l t«» a ronsidiTaMc c-xtt-nt in

pliotoj^rapliifwork on ut-connt of tlu- artinir proix-rlirs of llir li^'lit.

SiK-iial reactanir-s must Ik* providt-tl for a nu-rc-ury arc laujp opiTdting

on sin^'K--pliasr, aiti'rnatiii^'-ciirrcnt circuits.

The Moore Tube Lijjht. The Moore iijiht makes use of the

familiar (Icissler tul>c ilischarije—

discharjje (»f electricity through a

vacuum tulx"—as a source of illumination. The jiractical application

of this dischar'^e to a system of lighting has involverl a larjje amount

FIk. 29. wiring DIuctuih. Two 11 AuUmiutii- Laiii|»f> l" S<'ri»'!*.

of consistent research on the part of the inventor and it has now heen

l»roUf,'ht to such a staj,'e that several installations have lM>tn made.

The svstem has manv interestiii'' features.

In the normal methotl of installation, a ^'lass tuhe IJ

inches in

dianutiT is nuidi- up hy connectiii},' standard lengths of ^las-s tuhinjj

lop-ther until the total desired lenj^th is reache«l, and this continuous

tniM-, which forms the .source of lij,'htwhen in o|Kration, is mountet U-nealh

the ceilinjj of the rooni to Im- li^dited. 'I'll*' tidx* may Ik' of any reas«in-

id>h- len^'lh. acdijil values running' from 10 to "J'JO feel. In onler to

123


Tube dtatributed in

ccny form clcsiT0c^ to

lertyhts ofsoo/eet

provide an electrical discharge through this tube it is customary to

lead both ends of the tube to the high tension terminals of a trans-

former, the low tension side of which may be connected to the alter-

nating-current lighting mains. This transformer is constructed so

that the high tension terminals are not exposed and the current is

led into the tube by means of platinum wires attached to carbon

electrodes. The electrodes are about eight inches in length. The

ends of the tube and the high tension terminals are enclosed in a steel

casing so as to effectually prevent anything from coming in contact

with the high potential of the system. As stated, the low tension side

of the trans-

former is con-

nected to the

usual 60-cycle

lighting mains.

If direct current

is used for distribution, a motor-

generator set for furnishing alter-

nating current to the primary of

the transformer is required. Any

frequency from 60 cycles up is

suitable for the operation of these

tubes. At lower frequencies there

is some appreciable variation of

the light emitted. One other de-

vice is necessary for the suitable

operation of this form of light and

this is known as the regulator. In order to maintain a constant pres-

sure inside the tube, and such a constant pressure is necessary for

its satisfactory operation, there must be some automatic device which

will allow a small amount of gas to enter the tube at intervals while

it is in operation. The regulator accomplishes this purpose. Fig.

30 shows a diagram of the very simple connections of the system and

gives the relative positions occupied by the transformer, tube, and regu-

lator. Fig. 31 gives an enlarged view of the regulator, a description

of which and its method of operation is given as follows:

A piece of |-inch glass tubing is supported vertically and its bottom end

is contracted into a f-inch glass tube which extends to the main lighting tube.

Fig. 30. Diagram Showing Essential

Features of the IMoore Light. 1 . Liglit-

ing Tube; 2. Transformer Case;3. Lamp Terminals; 4. Trans-

former; 5, 6, 7, 8, Regulators.

124

Ill i:< ruu iJianiNO -^1

At the {Hiitit of contraction ut tht- huttoin of tin- {-inch tube tlu-rv U M-aliil

by means of ccnu-nt a J -inch c»rliun j>hij;, tin* |K>rc>fiity of which in nol nn-iii

enuugli to allow mercury to jiercolalc throuf;h it Lul which will (NTniit gmnsa

ea-sily to pasD, due to the hi);h vacuunt of the

lif^hting tube connected to the lower end of tin-

{)liii:, and approximately atmospheric jjressure

ubnve it. This carbon I'luK i-s normally com-

pletely covered with what wouM correspond to

a thimbleful of mercury which 8imi)ly seals the

pores of the carbon \>\ug, and therefore haa

nothing whatever to do with the conducting

pri)j)erties of the gas in the main tube which

pri)duces the light. Partly immers<'d in the

mercury and concentric with the carbon plug,

is another smaller and movable glas.s tube, the

upi>er end of which is filled w ith soft iron wire,

which acts as the core of a small solenoid con-

nected in series with the transformer. The

action of the solenoid is to lift the concentric

glass tube partly out of the mercury, the sur-

face of which falls and thereby causes the

minute tip of the conical shaped carbon plugto be slightly exposed for a second or two.

This expo-sure is .suflicii-iit to allow

n .small amount of gas to i-ntiT the tube,

the current fleereases .slif^htly, and the

earhon pluj^ is attain sealed. The process

above de.serihed takes j)laee at intervals

of about one minute when the tube is in

ojM-ration.

The eolor of the lij^ht eniitteil by the

tube dej)ends Uj)on the pas u.sed in it.

The re^ilator is fitted with .some chtni-

i<al arrangement whereby the proj)er gas

is adinittrd to it when the lube is in oj)era-

tion. Nitrof^en is employi-d when (he (iilu-

gives the highest ellieieney and the light

emitted when this gas is u.sed is yellowish

in color. Air gives a pink appearance (o

the tuU- and carbon dio.xiile is employed when a white light is desirttl.

Tabli' IX gives gem-ral data nii tin- M«M»re tuU' light. The

advatitagcs cljiimcd for this light arc: High ellicient-y, gmxl (xilor, and

low intrinsic brilliancy.

KiVuI.ttliiK Vnlx-o.

185


TABLE IX

Data on the Moore Tube Light

Length ofTube

i:ij:( TKic LK.nTixr. 33

Hire tla- turri'iit is a.ssuined u.s pus-sing from tlit- t«p mrlxm to

thf bottom oiu* as iiulicati-d by the arrow ami sigius. \\f (iiid, in the

direct-iurniit arc, tliat the most of (Ik- li},'ht issues from the tip of the

positive carl)on, or electnxle. and this portion is known as the cralrr

of the are. This erater lias a temperature of from .'i,(KJ(J° to3,o()()° C'.,

the temperature at whieh tlie carbon vaporizes, and gives fully S() to

ho% of the light furnished by the arc. The negative carlnin In-comes

pointed at the same time thai the positive one is hollowed out to form

the crater, and it is also incandescent but not to as great a degn-e as

the positive carl)on. Hctwci-n the electrodes there is a band of violet

light, the arc proper, and this|

r^^^—r—rr -r-i

is surrounded bv a luminous

zone of a golden yellow cohjr.

The arc proper does not fur-

nish more than 5% of the light

emitted when pure carl)on

electrodes are used.

The carbons arc worn

away or consumed l)y the „ \

"^ / Y /

passage of the current, the

positive carbon being con- . v y\ <ina

sumed about twice as rapidly

as the negative.

The light distribution

curve of a dlrtvt-CUrrnit arc, ^lK• 33. Distribution Curve f..r D. C .\rr

Ijunu' (Vertical lliiiio)

taken in a vertical plane, is

shown in Kig. 33. Here it is seen that the maximum amount of light

is given olT at an angle of about alP from the vertical, the negative

carbon .shutting oil' ilie rays of light ihai :irc thrown directly liown-

ward from (he ( latir.

If alternating current is use«l, the upper carbon U'comcs positive

and n<-galive alternately, and there is n«» <haine for a cniter to U*

forme.l. l)oth carbons giving olV the same amount of light aii.l Ining

consumed at about the same rate. The light distril)Ution curve of

an nltrnuitiiiff-riirrrnt nrr is slu)wn in l"'ig. 31.

Arc-Lamp Mechanisms, in a praclital lamp we must have not

only a |)airof carbons for producing the arc. I»ut also nieans for su|>-

|M)rtingthese carl)ons, together with suitable arrangements for leading

200

30O


the current to them and for maintaining them at the proper distance

apart. The carbons are kept separated the proper distance by the

operating mechanisms which must perform the following functions:

1. The carbons must be in contact, or be brought into contact, to start

the arc when the current first flows.

2. They must be separated at the right distance to form a proper arc

immediately afterward.

Fig. 34. Distribution Curve for A. C. Arc Lamp (Vertical Plane).

3. The carbons must be fed to the arc as they are consumed.4. The circuit should be open or closed when the carbons are entirely

consumed, depending on the method of power distribution.

The feeding of the carbons may be done by hand, as is the case

in some stereopticons using an arc, but for ordinary illumination the

striking and maintaining of the arc must be automatic. It is madeso in all cases by means of solenoids acting against the force of gravity

or against springs. There are an endless number of such mechanisms,

128

ELl-XTUU: Ll(.illlN(j 35

+ -V

^AyWwUvWWW

liiit a ftw only will \n- ilfscrilKtJ jierr. 'riity may Ix,- roughly divided

into throt' cla.s.ses:

1. Sliiiiit riiochani8inH.

2. Si-rics mi'diaiiisiii.t.

3. DifTerential iiiL'chuiii.sni8.

Shunt Mrrli(nii.iin,H. In shunt lamps, the oarlMias an- h.ld apartbt'forr tlu' curn-nt is turned on, and tlw cirfiiit is closed through a

solenoid conneitt'd in across the

gap so formed. All (jf the cur-

rent must pass through this coil

at first, and the plunger of the

solenoid is arranged to draw the

carhons together, thus starting

the arc. Thej)ull

of the solenoid

and that of th •

springs are ad-

justed U) maintain the arc at its

proper length.

Such lamps have the disad-

vantage of a high resistance at

the start—laO ohms or more—and are difhcult to start on series

circuits, ilue to the high voltage

re(|uire<l. They tend to maintain

a constant voltage at the arc, hut

do not aid the <lynamo in it:j

regulation, so that the arcs are

liahle to Im- a little unsteady.

Serici Mtch(nil.sm.s. With

the .series-lamp mechanisin, the

carbons are together when the himp is first started aiu' the current,

flowing in the series coil, sej)arati'sth»' electrodes, striking the arc.

When the arc is too long, the resistance is increased and the <urrent

Inweretl so that the pull of the solenoiil is weakened and the carlH)ns

feed together. This type of lamp can Ih" nsetl only on constant-

potetitial systems.

I'ig. 3') .shows a diagram of the conni-ction of such a lamp. This

diagnim is illustrative of tin- eoiuiecliun of one of the lamps maiui-

factured l>y the Western KIcctric ('<»mpany, for use on a dirvct-currerit,

FIk. 35. SorUlM M«vhaiil«jn for D CAn- I^iiiip.

isn


constant-potential system. The symbols + and — refer to the termi-

nals of the lamp, and the lamp must be so connected that the current

flows from the top carbon to the bottom one. R is a series resistance,

adjustable for different voltages by means of the shunt G. F and Dare the controlling solenoids connected in series with the arc. B and

C are the positive and negative carbons respectively, while A is the

switch for turning the current on and off. // is the plunger of the

solenoids and / the carbon clutch,

this being what

KJ

is known as a

carbon-feed lamp. The carbons

are together when A is first closed,

the current is excessive, and the

plunger is drawn up into the so-

lenoids, lifting the carbon B until

the resistance of the arc lowers the

current to such a value that the

pull of the solenoid just counter-

balances the weight of the plungerand carbon. G must be so adjustedthat this point is reached when the

arc is at its normal length.

Differential Mechanisms. In

the differential lamp, the series and

shunt mechanisms are combined,the carbons being together at the

start, and the series coil arrangedso as to separate them while the

shunt coil is connected across the

arc, as before, to prevent the carbons from being drawn too far apart.This lamp operates only over a low-current range, but it tends to aid

the generator in its regulation.

Fig. 36 shows a lamp having a differential control, this also beingthe diagram of a Western Electric Company arc lamp for a direct-

current, constant-potential system. Here S represents the shunt coil

and M the series coil, the armature of the two magnets A and A' beingattached to a bell-crank, pivoted at B, and attached to the carbon

clutch C. The pull of coil S tends to lower the carbon while that of

M raises the carbon, and the two are so adjusted that equilibrium is

Fig. 36. Differential Mechanism for

1). C. Arc Lamp.

130

ELECTRii ij(;irnN(;

n'aclinl wlu-n tlit- arc is of the projxT li-n^'tli. All «tf the lamps are

lit(f<l with an airtla.sli|)ut,

or some datiiping di'vice, to prevent too

rapitl nioveiiK'iits of the workiiij; j)art.s.

The rnetiuMJ.s of supporting,' tin- carl)oijs and feeding them to

the arc mav he divided into two classeij:

1. Roil-fcotl mocliatiiRtn.

Curboii-fecil tnuclmnUm.

Rod-Feed Mech a n ism.

Lamps usin<; a rtxl feed have

the upper carl)oiis supj)orte<l

hy a eonductinfj rixl, and the

re<,'ulating mechanism acts on

this rotl, the current bein<j fed

t(t the rod by means of a slidinj;

contact. Fig. 37 shows the ar-

rangement of this type of feed.

The rod is shown at R, the

sliding contact at R, and the

carbon is attached to the rod

at C.

These lamps have the ad-

vantage that carbons, which

tlo not luivc a uniform cross-

section or smooth exterior, maybe used, but they possess the

disadvantage of being very

long in order to accommodate

till- rod. The hmI imist als») be

k<|)f

clean so as to make a

good contact with the brush.

Cnrlioti-Fccd Merliani.'nii. In carlM)n-feed lam|)s tin* contntlling

me<'hanism acts on the carbons diredly through some fortn of eluleh

such as is shown at (' in Fig. .'{S. This damp grips the carlMni when

it is lifted, but allows the carbon to slip through it when (he tensitm

is relea.sed. I*'or this type of feed llu- carlton nuist U- stniight and

have a uniform eross-scrtion as well as a smcM>th ext«'rior. The

curn-nt mav be h d lo the carbun bv means of a ilexible lea«l an«l n

.short carbon holder.

Fli;. :^7. Koil-Fco.1 MivhaiiUwi.

i.n


TYPES OF ARC LAMPS

Arc lamps are constructed to operate on direct-current or alter-

nating-current systems when connected in series or in multiple. Theyare also made in both the open and the enclosed forms.

By an open arc is meant an arc lamp in which the arc is exposedto the atmosphere, while in the enclosed arc an inner or enclosing

8

Fig. :iS. Enclosed Arc Lamp with CiirbonFeed Mechanism.

globe surrounds the arc, and this globe is covered with a cap which

renders it nearly air-tight. Fig. 38 is a good example of an enclosed

arc as manufactured l)y the General Electric Company.Direct=Current Arcs. Open Types of Arcs for direct-current

systems were the first to be used to any great extent. Wlien used

thev are always connected in series, and are run from some form of

133

KLKCTRIC LIGHTING 39

sjx'cial arc niiichiiu', a tli-scription of which ma}' l>c found iti *'Tvpe3of l)viianio Elfftric MachiiuTV."

Kach himp ncjiiirt's in the nei<,'hl)orh(>o<l of 50 volts for its opera-

tion, ami, since the lamps are connected in series, the voltajje of tlje

svstein will depend on the nuniher of lamps; therefore, the numlnrr

of lam|)s that may l>e etjnnected to one machine is limite<l hv the

maximum allowahle volta^jc on that machine. Hy sjxH-ial construction

as many as 12'> lamps are run from one machine, hut even tiiis si/e

of [generator is not so eflicient as one of i;reater capacity. Such j^n-erators are usually wound for ().() or 0.() amperes. Since the carlHjns

are exposed to the air at the arc, they are rapidly consumed, rajuiringthat they Ik> renewed daily for this type of lamp.

Duiibh'-carboii arcs. In order to increase the life of the earlyform of arc lamp without usinfj; too long a carbon, the douhle-carbtjn

ty[>e was introduced. This type uses two sets of carhons, Ixjth si-ts

licing fed l)y one mechanism so arranged that when one pair of the elec-

trodes is consumed the other is put into service. At present nearlyall forms of the open arc lamp have disappeared on account of the

better service rendered by the enclosed arc.

Enclosed arcs for series systems are constructed much the same

as the open lamp, and are controlled l)y either shunt or dilferential

mechanism. They require a voltage from OS to 7') at the arc, and are

usually constructed for from o to (i.S amj)eres. They also rerpiire a

constant-<urrent generator or a rectider outfit if used on alternating-

current circuits.

Coti.ffanl-potcniial arcs must have some resistance connecttni in

series with them to keep the voltage at the arc at its pro[>er value.

This resistance is made adjustable so that the lamj)S may be used on

any circuit. Its lo<-ation is clearly shown in Fig. 3K, one coil U-ing{(Mated alK)Ve, the other below the operating solenoids.

Alternating-Current Arcs. These do not dilfer greatly in eon-

striKliiiii fniiii (hr din(t-<urrent arcs. When iron or other ujetal

parts are used in the controlling mechanism, they must Ik> laminated

or so constnu'ted jis to keej) down induced or e<ldy eurnnts which

might lie s«'t up in them. For this reason the metal s|mh»Is, on which

the solenoids are wound, are slotted a( some point to prevc-nt them

from funning n close«l .se<'onilary to the primary forme«| by the solen-

oid winding. On constant-|)otenlial circuits a n-active coil is used

133


in place of a part of the resistance for cutting down the voUage at the

arc.

Interchangeable Arc. Interchangeable arcs are manufactured

which may be readily adjusted so as to operate on either direct or

alternating current, and on voltages from 110 to 220. Two lamps

may be run in series on 220-volt circuits.

The distribution of light, and the resulting illumination for the

different lamps just considered, will be taken up later. Aside from

the distribution and quality of light, the enclosed arc has the advan-

tage that the carbons are not consumed so rapidly as in the open lampbecause the oxygen is soon exhausted from the inner globe and the

combustion of the carbon is greatly decreased. They will burn

from 80 to 100 hours without retrimming.

TABLE X

Rating of Enclosed Arcs

ELECTRIC LKillTING 41

Full Arcs, 2.(XX) cniHlle-jKiwer taking 9 5 to 10 uinjxi. or 450- ISO watt*.

Half Area, 1,200 caiulle-power taking Co to 7 ainiM. or 325-350 watu.

These fan«IK--[K)\vor ratings arc iiukIi Um} lii^li, atul run more

iR-arly 1,2U() ami 7lM», resjK'ftivfly, f<»r tlic point of inaxiiiuiin intensitv

ami Ifss than this if tht> mean sphrrical candlf-powt-r Ik* taken. For

tliis reason, the ampere or watt rating is now use«] to indicate the

fM)Wcr c)f the hinip. It is now rc<(nnmen(Je(l that sfM'cifications f()r

street lighting should he hased upon the illumination pnxluced. This

point is considered later under thetoj)ic of street lighting. Enclosed

arcs use from 3 to 6.o amperes, hut the voltage at the arc is higher

than for the open lanij). Tahle X gives some data on enclosed arcs

on coastant-potential circuits.

Efficiency. The efliciency o* arc lamps is given as follows:

Direct-Current Arc (enclosed) 2.9 watts per candle-power.

.Mternating-Current .\rc (enclosed) 2.95 watts fier candle-power.Direct-f'urrent .Arc fojwn) .G-1.25 watts jx-'r candle-power.

Carbons for .Arc Lamps. Carbons are either moulded or forced

from a j)ro«luct known as petroleum coke or from similar materials

such as lampblack. The material is thoroughly dried by heating to a

high temj)erature, then ground to a find powder, and combined with

some substance such as pitch which binds the fine particles of carbon

together. After this mi.xture is again ground it is ready for moulding.The j)owiler is put in steel moulds and heated until it takes the form

of a paste, when the necessary pressure is a|)plied to the moulds. Kor

the forced carbons, the powder is formed into c-yliiiders which nrv

placed in machines which force the material through a die .so arrange*!

as to give the desire*! diameter. 'I'iie force*! carl)ons are *)fti'n madewith a core of .some special niat*'rial, this core b*-ing added after the

carbon proper has been (inl^lnij. Tlic carbons, whetln-r tnouldetl

or forced, niu>t Im- can-fully baked to drive olF all volatile matter.

I'he force*! carbon is always more uniform in i|uali(v ;iiid *"n>s.s-

.se<'tion, and is tin- ty|M> of carlxxi which nuist Ik* us*'*! in the *'arlHm-

f*'e<| lamp. Th*- a<l*ling of a *i)re of a «lin'*'r*-nt mat*>rial seems t*'»

ehang*' the «|UJility of light, and being more reatlily volulilizcxl, keepv;

the are from wandering.

I'laling of «arb*)ns with *'*>p|MT is .sometimes n'.sort*"*! t*> for

ni*>uld*-*l forms for (he purjMts*- of in*rea.sing llu- *-on*lu«(ivi(v, un*l,

by protecting the carb*>n near the are. prol*>nging tlu- life.

186


The Flaming Arc. In the carbon are the arc proper gives out

but a small percentage of the total amount of light emitted. In order

to obtain a light in which more of the source of luminosity is in the

arc itself, experiments have been made with the use of electrodes im-

pregnated with certain salts, as well as with electrodes of a material

different than carbon. The result of these experiments has been to

place upon the market the flaming arc lamps and the luminous arc

lamps—lamps of high candle-power, good efficiency, and giving vari-

ous colors of light. These lamps may be put in two classes : One class

uses carbon electrodes, these electrodes being impregnated with certain

salts which add luminosity to the

arc, or else fitted with cores which

contain the required material;

the other class covering lampswhich do not employ carbon, the

most notable example being the

magnetite arc which uses a copper

segment as one electrode and a

PorceZairt

Afeial

magnetiteEconomizef

Fig. 39. Diagram of Bremer Fiaming Arc.

stick as the other

electrode.

Flaming arcs of the first class

are made in two general types:

One in which the electrodes are

placed at an angle, and the other in which the carbons are placedone above the other as in the ordinary arc lamp. The term lumi-

nous arc is usually applied to arcs of the flaming t}^e in which the

electrodes are placed one above the other. The minor modifications

as introduced by the various manufacturers are numerous and include

such features as a magazine supply of electrodes by which a new pair

may be automatically introduced when one pair is consumed; feed

and control mechanisms; etc. The flaming arc presents a special

problem since the vapors given off by the lamp may condense on the

glassware and form a partially opaque coating, or they may interfere

with the control mechanism.

Bremer Arc. The Bremer flaming arc lamp was introduced

commercially in 1899, and since some of its principles are incorporatedin many of the lamps on the market to-day, it will be briefly described

here. The diagram shown in Fig. 39 illustrates the main features of

136

Kl.lXTUK LKillTING 13

\

thislaiii|).

I'lii' fU'ftrtxN's an- iuoiiiitf<| at an angle and an fltftrt>-

nuignt't isplac*'*!

alnivf the are for thepnr|)4is4> of keeping the arc from

creeping up anil injuring the economizer, an<l also for the pur|M*se of

spreading the are out and increasing its surface. The vajxir from

the arc is condensed on the economizer and this coating acts as a re-

flector, throwing the light downward. The economizer senes to

limit the air sup|)lied to the arc and thus increases the life of the elec-

tHMles. The inclined jjosition of the carhons was suggested hv the

fart that in the impregnated carbons a slag was formed which gavetrouble when the electrodes were mounted in the usual maimer. Byusing the electrotles in

this position there is little

if any obstruction to the

light which passes di-

rectly downward from

the arc.

Bremer's original

electrodes contained o'

compounds of calcium, /o'

strontium, magnesium, so'

etc., as well as boracic j(

acid. Electro<les as em-

ployed in tile various

lamps to-day ditfer

greatly in their make-u|).

Some u.se impregnated

carbons, others use carbons witii a core containing the flaming ma-

teri.ils, and metallic wires arc aihlrd in some ca.ses. The life of

electnxles for flaming lamps is not great, (lej)ending ujioii their length

and somewhat upon the ty|tcof lam|). The maximum life t)f the

treateil carbons is in the neigliborhood of l2l) hours.

The <'o|or of the light from th«' flaming an- is yellow when cal-

cium salts are used as the main impregnating compound, and the

njajority of (he lamj)s installed us(> electrtnles giving a yellow light.

By employing more strontium, a wA or pink light is pnMluceil, while

if :i white light is wanted, bariunt salts are iiscd. Calcium gives the

most eflicieiit service and strontium «onH's In'tween this and Itarium.

The distrilmtion curves in l-'ig.Id illustrate the relative e<.n)nuiuivs

y

eo'~9o*' BO'

FIr. 40. Dlstrll)iitlr)ii Ciirvi-sof a I.iimlnous Arc.

1M7


of the different materials. Modern electrodes contain not more than

15% of added material and it is customary to find the salts appliedas a core to the pure carbon sticks. The electrodes are made of a

small diameter in order to maintain a steady light and this partially

accounts for their short life.

The feeding mechanisms employed differ greatly. They may be

classified as: Clock, gravity-feed, clutch, motor, and hot-wire mech-

anisms. Fig. 41 illustrates a clock mechanism. This is a dif-

ferential mechanism in which the

sluint coils act to release a detent /which allows the electrodes to feed

down and when they come in con-

tact the series coils separate them

to the proper extent for maintaininga suitable arc. In the gravity feed

an electromagnet is used to operateone carbon in springing the arc and

the other carbon is fed by gravity,

it being prevented from droppingtoo far by means of a special rib

formed on the electrode which comes

in contact with a part of the lampstructure. Gravity feed is also em-

ployed in the clutch mechanism but

here the carbons are held in one

position by an electrically operatedclutch which releases them onlywhen

the current is sufficiently reduced bythe lengthening of the arc. In the

hot-wire lamp, the wire is usually in series with the arc; the contrac-

tion and expansion of this wire is balanced against a spring and the

arc is regulated by such contraction or expansion of the wire. Such

a lamp is suitable for either direct or alternating current. In the

motor mechanism, as applied to alternating-current lamps, a metallic

disk is actuated by differential magnets and its motion is transmitted

to the electrodes to lengthen or shorten the arc accordingly as the

force exerted by the series or shunt coils predominates.

Magnetite Arc. The magnetite arc employs a copper disk as

Fig. 41. Clock Feeding Mechanism for

Luminous Arc Lamp.

138

'^ V.HH

mI/)

3OX

I

eeM

<XU

0.

< .

J .

in z

< ^

isO u

(is

«3o

" -3"- a

i •

c §

> ::

_ 3> J

z z""

eetid oK u£>-

KUId

az<

o

•^ ,::

KLKC rUK LKiirriNO 45

one elcctnKlf, and a inaffru'titr stick— fornittl by forcing ma^jiietitc,

t«» whicli titanium salLs are usually a<ltlc<l, into a thin sheet steel tub*'—is used as tin- other eleetrtMh-. This lamp j:^vi-s a luminous are of

ij(Kxl eUifieticv anil the magnetite electrode is not corLsumitl as rapidly

as the treate*! carlions with the result that magnetite latn[>s do not

require trimming as frc<jurntly. Tin- life of the magnetite electro<Jc

as at present manufactured is from 170 to L'(M) lujurs. A diagram of

the connections of this lamp as manufactured hy the General Klectric

Starling /'

[ [

Magnet tV

^^^Pig. 42. ItlaKrniii «f C^mnertloiiK for Magiietlto Arc I.«nip

Tornpanv is shown in Fig. 42. The magnetite electnnle is phuvd U'-

low. The coppiT electrode has just the prop<T dimensions to prevent

its luing destroy«<l hy the arc and yet i( is not large enougli to cau.se

undue conden.sation of the arc vajxir. Direct curn-nt must U> u.sjti

with this lamp, the current |)a.ssingfrom the copper to the magnetite.

Tahle XI gives some general data on (lu- (laming arc, while Figs.

I.', and 14 give typieal dislrihulion (ur\es. Tin- a«lvaintages of the

llaming arc over lamps tising pure earhon ileclriKles an-: Miglj efli-

eiency; Utter light distril)Ution; and heller color of lighl for some

189


purposes, A greater amount of light can be obtained from a single

unit than is practical with the carbon arc. The disadvantages lie

in the frequent trimming required and the expense of electrodes.

Flaming arcs have been introduced abroad, especially in Germany,to a much greater extent than in the United States.

TABLE XI

General Data on Flaming Arcs

Volts

ELF.rTRIC LIGHTINn

any iuhiiIht of fircuits can Ik- run from om? machine or set of bus bars,

ami apparatus can Ik* l)uilt for any voltage aiul cjf any size. It Is not

customary, however, to build transformers of this tyjx* having a capac-

4360' 75' 90' 75' ec

Fig. 43. Distribution Curve for FlaniiiiKArc Lamp.

ity greater than one hundred (l.Ci-anipere lamps tx'cause of the high

voltage which would have to be induced in the secondary for a larger

number of lamps.

Luminous Arc LampDirect current series circuit.

LiQht ["tstrihuttcn \ ^ \

Fig. 4') gives a dia-

gram of the connection

of a singleH'oil traas-

fonner in service. The

constant-<'urrent tran.s-

former most in u.sc for

lighting purposes is the so'

one tnanufactured by the

(leiieral Flictric Com-

pany and commonlyknown as a tub traii.s-

fiirmrr. I''ig.Mi shows such a transformer (tlouble-<-«iil ty|>«')

when

rtinovrd frniii (he cas**.

Referring to Fig. Hi, the fixed coils .1 form the primaries which

are comiecteil acro.s.s the line; the movable coils li are the .secondaries

40' 50' 60'

o'

10*

20'

30'

50' ^O'I''i»r. 4'l. DlHtrii'MM :rM .

•.1 4- Aiiiivnv

T.'V-Nolt. .Muk'ii*-lil<< l.uMiliioiiN .\n- l.aiii|>

141


SECONDARY—x-x—x—X—X—X—LAMPS

LIGHTNINGARRESTER(^

ARC AMMETER

connected to the lamps. There is a repulsion of the coils B by the

coils A when the current flows in both circuits and this force is bal-

anced by means of the weights at W, so that the coils B take a position

such that the normal current will flow in the secondary. On light

loads, a low voltage is sufficient, hence the secondary coils are close

together near the middle of

the machine and there is a

heavy magnetic leakage.

\Mien all of the lamps are

on, the coils take the posi-

tion shown when the leak-

age is a minimum and the

voltage a maximum. Whenfirst starting up, the trans-

former is short-circuited and

the secondary coils broughtclose together. The short

circuit is then removed and

the coils take a position

corresponding to the load

on the line.

These transformers regu-

late from full load to J rated

load within ^V ampere of

normal current, and can be

run on short circuit for

CURRENTTRANSFORMER

OMIT FOR25 LIGHTS

OPEN CIRCUTING^ PLUG SWITCHESSHORT CIRCUITING

PLUG SWITCH

i

T

CONSTANT CURRENTTRANSFORMER

RESISTANCE

FUSE

POTENTIALTRANSFORMER

PRIMARYBACK VIEW

CFUSE

CPRIMARY PLUG SWITCH several hours without over-

Fig. 45. AViring Diagram for Single-Coil

Transformer.

heating. The efficiency is

given as 9G% for 100-light

transformers and 94.6% for

50-light transformers at full

load. The power factor of the system is from 76 to 78% on full

load, and, owing to the great amount of magnetic leakage at less than

full load—the effect of leakage being the same as the effect of an in-

ductance in the primary—the power factor is greatly reduced, falling

to 62% at I load, 44% at ^ load, and 24% at i load.

Standard sizes are for capacities of 25-, 35-, 50-, 75-, and 100-6.6

ampere enclosed arcs, and they are also made for lower currents in

142

KLia ruic LK.iniNd \'.)

9

It

c

st

c

Ma


the neighborhood of 3.3 amperes for incandescent lamps. The low

power factor of such a system on light loads shows that a transformer

should be selected of such a capacity that it will be fully or nearly

fully loaded at all times. The primary winding can be constructed

for any voltage and the open circuit voltages of the secondaries are

as follows:

25 light transformer, 2,300 volts.

35

50

3,200

4,600

75 light transformer, 6,900 volts.

100 " "9,200

"

The 50-, 75-, and 100-light transformers are arranged for multiple

circuit operation, two circuits

used in series, and the vol-

tages at full load reach 4,100

for each circuit on the 100-light

machine.

The second system, used

for series distribution on

alternating-current circuits

consists of a constant-potential

transformer, stepping down the

line voltage to that requiredfor the total number of lampson the system, allowing 83

volts for each lamp, and in

series with the lamps is a

reactive coil, the reactance of

which is automatically regu-

lated, as the load is increased

or decreased, in order to keepthe current in the line con-

stant. Fig. 47 shows such a regulator and Fig. 48 shows this regu-

lator connected in circuit. The inductance is varied by the move-

ment of the coil so as to include more or less iron in the magneticcircuit. Since the inductance in series with the lamps is high on light

loads, the power factor is greatly reduced as in the constant-current

transformer; and the circuits should, preferably, be run fully loaded.

60 to 65 lamps on a circuit is the usual maximum limit.

WTiile used primarily for arc-light circuits, the same systems,

Fig. 47. Current Regulator for A. C. Series

Distribution Systems.

144

Ki.Kc-niic LKMITlXr; 51

C.P. STEP UPOR STt-PCXDWNTRANSFORMER

CI RCCULATOR

<K-.si«,'mtl for lower currents, are very readily applied to series incan-

descent systems.

The iiitHKluction of certain (laming or luminous arcs rwjuiringdirect current for their operation has led to the use of the mercury arc

ricHjur in connection with series circuits on alternating-c-urrent

systems. A constant-c-urrent transformer is used to regulate for the

proper constant current in its second-

ary winding, and this secondary current

is rectified by means of the mercury arc

rectifier for the lamp circuit. In the

recent outfits the rectifier tubes are

immersed in oil for cooling. While

this rectifier was first introduced for

the operation of luminous arc lamps,

there is no reason why it should not

he used with anv series lamp re(|uiriiig kicking

direct current, provided the .system is

designed for the current taken by su( h

lamj)s. With this system any commer-

cial frequency may be used. Sets are

constructed for 2.')-, 50-, and To-light

circuits. They have a combined effi-

ciency, transformer and rectifier tube,

of S')'^l to 009^, and operate at a powerfactor of from ().j% to 70%. Fig. 40

gives a diagram of the circuit and

rectifier connections used with a single- fir. .is. wiring niain^m .siiowIhr in-

. I ,f. tnxluctloii of tlio Current Utvulator.tunc ollttlt.

A\uhiplc-Sc'rics or Series-Multiple Systems. These combine

.several lanij)s in .series, and tlu-.se .scries groups in mulliple, or .several

Iam[>s in nuiltiple and these multiple groups in .scri«-s, rcsp«'ctively.

Thcv li.ivc bill ;i limiteda|>|>lir,iti()ii.

Multiple or Parallel Systems of I)istril)uti»>n. Uy far the largest

numlM-r of lamps in .service are connecte«l to parallel .systems of tli.s-

tribulioii. In this .system, the units are conncct«-<l acros,s the lines

leading to (he l)us bars at the station, or to the .secondaries of ct»n-

staiit-potcntial transformers. Fig. '>() shows a <liagram of ten lamps

connected in parallel. The current di-liviTcd by the machine de-

~ll-'\ riif\ UCHTNINCjj^ [MJ arrester:

140


pends directly on the number of lamps connected in service, the vol-

tage of the system being kept constant.

Inasmuch as the flow of current in a conductor is always accom-

panied by a fall\//o-^zSACBt/sses

Tube Tanff

Trcfns

/^•?Tiynefe-r corl-necied ioATTimcase

STafzcZ>7SC

--

r^ maIa^t^wv^

a-nd

:^M^myrteier-

Jf^'^>\Load

Arreslir-

Load ,® SwiJcnes—@— ShoT^ Circtyii

t

Ifiaaliififl

V V v>

foT- &0% Load Con yicc*7zor?.

5i^7ic?3'e%

of potential equalto the product of

the current flow-

ing into the resist-

ance of the con-

(hictor, the lampsat the end of the

system shownwill not have as

high a voltage

impressed uponthem as those

nearer the ma-

chine. This

drop in potential

is the most seri-

ous obstacle that

we have to over-

come in multiple

systems, andvarious schemes have been adopted to aid in this regulation. The

systems may be classified as :

1. Cylindrical conductors, parallel feeding.

2. Conical

'.i. Cylindrical"

anti-parallel feeding.

4. Conical " " "

In the cylindrical conductor, parallel-feeding system, the con-

ductors, A, B,C, D, Fig. 50, are of the same size throughout and are

fed at the same end by the generator. The voltage is a minimumat the lamps E and a maximum at the lamps F; the value of the

voltage at any lamp being readily calculated.

By a conical or tapering conductor is meant a conductor whose

diameter is so proportioned throughout its length that the current,

divided by the cross-section, or the current density, is a constant

Fi/sts

Fig. 49. weiring Diagram for A. C. System Showing Iiitrixluc-

tion of Mercury -Vrc Rectifier.

146

II I< I'HIC F.KMI'IMNC Xi

B

Fig. 50. ParallW Kcctling Sytftfin.

KIg. 51. .Viitl-pan-llel Ki-cilInK System.

Miiaiitilv. Swell a i oiuliHiur i-. appnixiiuatctl in praclitt' bv using

ÎIlalI^•^ .sizt'.s of win- as tlir ciirrtMit in tlu* liiirs Ix'i-onu'S |fs.s.

In un anti-paralUI systi-ni, ilu- currftit is fed to the lumps from

n|i|)<)siteends of the .system, as sh«i\vii in Ki;,'. .'»!.

Multiple W ire S\stcms. In order to take advantajje of a hi<;her

voltage for distrilmlion of power to the li;:htinf; einuits, three- and

five-wire svstenis have been intriMJueed, the three-wire .system U-ing

iis«'d to a verv lar^'e extent. In this .system, thri'c- eonduetors are

used, the voltajê from each

outside conductor to the

miildle neutral conductor

hcini: the .same as for a

simple parallel .system. Fi{^.

.')2 gives a dia<jram of this.

Bv this system the amount

of copper recjuired for a j,'iv-

en number «)f lamps is from

fi ve-si.\tcenths to three-

eighths of the amount

required for a two-wire dis-

tribution, depending on the

size of the neu t ral con-

ductor. The saving of

copjH-r together with the disadvantages of the .system is more fully

treatcfl in the paper on "Tower Transmi.ssion."

ILLUMIN.ATION

Illumination may l«' dc(ine<l as the (pialily and (|Uanlily of light

which aiils in the <liscriinination of t>utline and the |)erccptionof

color. Not only the <iuantity.bnl ilie ipuility

of the light, as well as

the arrangement r)f the units, must be eonsidere<l in a complete study

of the subject of illumination.

Init of Illumination. TIk- unit of illumination is the/<»<>/-

ramlli and it- value is the amount of light falling on a .surfatv at a

distance of one foot from a soun e of light one candle-iM»wer in value.

I'll.- law of inverse .sf|uan's— namely, that the illumination frtun a

given .sourcj- vari«s inversely as the scpnire of the distinuv fnun the

ûrct,—shows thai the illumination at a distanc«- of two feet fn>m a

riint -» iri- S: <v\i

117


single candle-power unit is .25 foot-candles. For further con-

sideration of the law of inverse squares, see "Photometry."

Illumination may be classified as useful—when used for the

ordinary purposes of furnishing light for carrying on work, taking

the place of daylight; and scenic—when used for decorative lighting

such as stage lighting, etc. The two divisions are not, as a rule,

distinct, but the one is combined with the other.

Intrinsic Brightness. By intrinsic brightness is meant the

amount of light emitted per unit surface of the light source. Table

XII gives the intrinsic brightness of several light sources.

TABLE XII

Intrinsic Brilliancies in Candle-Power per Square Inch

Source

ELECTRIC LICIITING 55

I )itl'iis((l rifltiiii)M is virv importaiit in tin- .>tu«lv of illuniinatidn

inasniiK'h as diirusttlli|;lit plavs an

iin|)(jrtaiit part in tlu* lighting of

interiors. 'I'liis form of rcflettion is seen in many photometer sereens.

Light is also tlitTused when passing through semi-transparent shades

or screens.

In considering reflected light, we find that, if the surface on

which the light falls is coloreil, the reHe<ted light may l)c changeythe absorption of some of the colors. Since, as has Ixt-n

said, in interior lighting the reflected light forms a large part of the

source of illumination, this illumination will depend upon the nature

and the color of the reflecting surfaces.

Whenever light is reflected from a surface, either by direct or

difTused reflection, a certain amount of light is absorbed by the surface.

Table XIII gives the amount of white light reflected from different

materials.

TABLE XIII

Relative Reflectia}; Power

Matkiiial

Whito hlottinu puiH-r^\'l^itl• cartri(,lj;c pajKrChniiiie yellow paper( )raiip(' paiKTVclliiw wall pai)f'r

Lifjhl pink pajHTYellow eanlhoard

Light l)lue cardboardI'riH-rald preen paperDark brown pafjer. . ,

Verrnili<jii paf>orIMin-preen paper. .

Hlack pa|»erIMaek clothl?l!i(k velvet

s-j

soG2504036.U)

•Jo

IS13

1_'

IJr,)

1 -'

1

I-'rom this laliie i( is setii that the light-colored papers reflect the

light well, but of the darker colors only y«'llow has a companilivelv

high c(M-fIicient of reflection. Black velvet has the lowest value, but

this only holds when the material is free fn»m dust. H(H>ms with

dark walls re«|uire a great«T amount of illuminating power, as will In-

seen hiter.

Usi'ful illumination may be considered under the following

heads:

140

5G ELECTRIC LIGHTING

1. Residence Lighting.2. Lighting of Public Halls, Offices, Drafting Rooms, Shops, etc.

3. Street Lighting.

RESIDENCE LIGHTING

Type of Lamps. The lamps used for this class of lighting are

limited to the less powerful units—namely, incandescent or Nernst

lamps varying in candle-power from S to 50 per unit. These should

always be shaded so as to keep the intrinsic brightness low. Theintrinsic brilliancy should seldom exceed 2 to 3 candle-power per

square inch, and its reduction is usually accomplished by appropriate

shading. Arc lights are so powerful as to be uneconomical for

small rooms, while the color of the mercury-vapor light is an additional

objection to its use.

Plan of Illumination. Lamps may be selected and so located

as to give a brilliant and fairly uniform illumination in a room;but this

is an uneconomical scheme, and the one more commonly employedis to furnish a uniform, though comparatively weak, ground illumi-

nation, and to reinforce this at points where it is necessary or desirable.

The latter plan is satisfactory in almost all cases and the more eco-

nomical of the two.

While the use of units of different power is to be recommended,where desirable, lights differing in color should not be used for lighting

the same room. As an exaggerated case, the use of arc with incan-

descent lamps might be mentioned. The arcs being so much whiter

than the incandescent lamps, the latter appear distinctly yellow whenthe two are viewed at the same time.

Calculation of Illumination. In determining the value of illumi-

nation, not only the candle-power of the units, but tlie amount of re-

flected light must be considered for the given location of the lamps.

Following is a formula based on the coefficient of reflection of the

walls of the room, which serves for preliminary calculations:

1

c.p. r

= 1 - ^

I = Illumination in foot-candles.

c.p.=

Candle-power of the unit.

/;;= Coefficient of reflection of the walls.

d = distance from the unit in feet.

150

rr.ECTRIC LKJIITING 57

WluTf st'Vcral units of tin- Naiiir «aiiilir-jMiwrr art- iisitl lhi.s

fiiiiiiiila lM'(()mt-< :III 1

or, r.p. =1 1 1 1

^iP

•"

^/=,

"^

rf^,

^ "^1 -

it

where rf, (/j, d.,, ttc, e(|ual tlic (Jistanc-es from the point consiih-red to

the various li^ht sources. If the lamps are of dilFereiit eaiulU'-|>o\ver,

the ilhiniinatioii inav be detenniiicd hv eoinbiiiiii'' the ilhiiniiiation

from eacli source as calculated separately. An e.\anij)Ie of calculation

is given uiitler "Arrangement of Lamps."The above metluxl is not strictly accurate because it does not

take account of the ande at whicji the li<rht from each one of the

sources strikes the assumed plane of illumination. If the ray of

light is perpendicular to the plane, the fornuda I =-^givcs cor-

rect values. If (/ is the angle which the ray of light makes with a line

drawn from the light source perpendicular to the assumed plane,

then the fornmla becomes I = '''^'^^'2'^^^" ' 1''»'refore. by

multiplying the candle-power value of each light source in the dire(-

tion of the illuminated jioint l)y the cosine of each angle a, a more

accurate result will be obtained.

It is readily .seen that the elTcct of reflecteil light from the ceilings

is of more importance than that from the floor of a room. The value

of /;. in the al)ove formula, will ^ary from ^\{Yy^ to \{)^[ ,but for riHtms

with a fairly light finish ')()^l may be taken as a goinl average value.

The amount of illumination will dejM-iid on the use to U- made of

the room. < )nc foot-<andlc gives suflicicnt illumination for easy

reading, when measured normal to the page, and probably an illumi-

nation of ..") foot-candle on a plane .5 feet from the tliMir forms a sufli-

cienl ground illumination. The illumination from sunlight rellwteil

fn»m whil«' clouds is from L'O foot-<-andles up, whih- that «lue to iiuhmi-

light is in iId* nei^hborlxMMl of .().'{ fiH>tH-andles. It is i,ot ixwsibh* to

priNluce artificially a light eipiivalent to daylight on ai-count of the

\r>\


great amount of energy that would be required and the difficulty of

obtaining proper diffusion.

The method of calculating the illumination of a room that has

just been described is known as the point-bij-pointmethod and it

gives very accurate results if account is taken of the angle at which

the light from each source strikes the plane of illumination and if

the light distribution curves of the units, and the value of k, have been

carefully determined. Under these conditions the calculations be-

come extended and complicated and methods only approximate, but

simpler in their application, are being introduced. One method,

which gives good results when applied to fairly large interiors, makes

the flux of light from the light sources the basis of calculation of the

average illumination.

Flux of light is measured in lumens and a lumen may be defined

as the amount of light which must fall on one square foot of surface

in order to produce a uniform illumination of an intensity of one foot-

candle. A source of light giving one candle-power in every direction

and placed at the center of a sphere of one foot radius would give an

illumination of one foot-candle at every point in the surface of the

sphere and the total flux of light would be 47r, or 12.57, lumens since

the area of the sphere would be 47r, or 12.57, sq. ft. A lamp giving

one mean spherical candle-power gives a flux of 12.57 lumens and

the total flux of light from any source is obtained by multiplying its

mean spherical candle-power by 12.57. In calculating illumination

it is customary to determine the illumination on a plane about 30

inches from the floor for desk work, and about 42 inches from the

floor for the display of goods on counters. If we determine the total

number of lumens falling on this plane and divide this number by

the area of the plane, we obtain the average illumination in foot-

candles. This of course tells us nothing about the maximum or

minimum value of the illumination and such values must be obtained

by other methods if they are desired. Reflected light, other than that

covered by the distribution curve of the light unit including its re-

flector, is usually neglected in this method of calculation.

We may assume that in large rooms the light coming from the

lamp within an angle of 75 degrees from the vertical reaches the plane

of illumination. In smaller rooms this angle should be reduced to

about 60 degrees. In order to determine the flux of light within this

152

FT.FrTRIC LUiHTING 59

uii^'U- u lioussetiu diagram, which is desc-ribttl hiter, should Ix* drawn.

IJy the ineaiLS of this diagram tlie avi-rage candle-[X)W'er of the light

source within tiic angU' assumed may Ix* readily determined and tliis

mean vahie, muhiphed hy 12.57, will give the flu.x of light in lumciLS.

This metluKl of calculation, together with some guides for its rapid

application, is described hy M<-ssrs. Cravath and Laasingh in the

"Transactions of the Illuminating Engineering Society, I'.MJS." The

same authorities give the following useful datii:

To determine the watts recjuired j)er square foot of floor area,

nuiltiply the intensity of illumination desired by the constants given

as follows:

INTENSITY CONSTANTS FOR INCANDESCENT LAMPS

Tungsten lamps rated at 1.25 watts per horizontal candle-power; clear

prismatic reflectors, either bowl or concentrating; large room; light

ceiling; dark walls; lamps pendant; height from 8 to 15 feet .25

Same with very light walls 20

Tungsten lamps rated at 1.25 watts per horizontal candle-power; pris-

matic bowl reflectors enameled; large room; light ceiling; dark

walU; lamps pendant, hoiglit from S to 15 feet 29

Same with verj' light walls 23

Gem lamps rated at 2.5 watts per horizontal candle-jMiwer; clear pris-

matic reflectors either concentrating or bowl; large room; light

ceiling; dark walls; lamps pendant; height from S to 15 feet. ... 55

Same with very light walls 45

Carbon filament lamps rated at 3.1 watts per horizontal canille-power;

clear prismatic reflectors either bowl or concentrating; liglU ceiling;

dark wali.s; l.n m; lamps pendant ; height from 8 to 15 feet . . .65

Same with very 11- 55

Bare carbon fdament lamps rated at .3.1 watts |)er horizontal candlc-

ix)wer; no rrflcctors; large room; very light ceiling and walls;

height from 10 to 14 feet 75 to 1 .5

Same; small room; me<lium walls . . 1 .25 to 2.0

Carbon filament lamps rated at .'5.1 watts fn-r horizontal c i

opal dome or opal cone reflectors; ligiit ceiling; dark >

room; lumps [x'tidant; height from 8 to 15 fe«'t 70

Same with light walls .GO

INTENSITY CONSTANTS lOR ARC LAMPS

5-am()ere, encloMj-d, din-ct-current arc on lU)-vult circuit; clear inner,

opal oiitrr globe; no n-di-rtor: large room; light ceiling; medmiu

walls li.iglK from 9 to 14 feel 50

Arrangcnicni <ii Lamps. .\ii :irrang«-ment of lamps giving ti

uniform ilhnnination cannot Im- well applied to nvsid«Murs on H<"eount

uf the numU'r of units re«piired, and the inartistic cfTcct. Wc arc

1&3

<M

limited to chandeliers, side lights, or ceiling lights, in the majority

of cases, with table or reading lamps for special illumination.

^^^len ceiling lamps are used and the ceilings are high, some

form of reflector or reflector lamp is to be recommended. In anycase where the coefficient of reflection of the

I ceilings is less than 40%, it is more economical

to use reflectors. \Mien lamps are mounted

on chandeliers, the illumination is far from

uniform, being a maximum in the neighbor-

hood of the chandelier and a minimum at the

corners of the room. By combining chande-

liers with side lights it is generally possible to

f| IV)§^^^ ^ satisfactory arrangement of lighting for*^ small or medium-sized rooms."* As a check on the candle-power in lamps

I

' " -required, we have the following :

T For brilliant illumination allow one candle-

Fig. 53. Diagram Showing Po^'^r per two square feet of floor space. In some

Method of Calculatuig particular cases, such as ball rooms, this may beRoom Illumination. increased to one candle-power per square foot.

For general illumination allow one candle-powerfor four square feet of floor space, and strengthen this illumination with the

aid of special lamps as required. The location of lamps and the height of

ceilings will modify these figures to some extent.

As an example of the calculation of the illu-

mination of a room with different arrangements

of the units of light, assume a room 16 feet

square, 12 feet high, and with walls having a <e-

coefficient of reflection of 50%. Consider first

the illumination on a plane 3 feet above the

floor when lighted by a single group of lights

mounted at the center of the room 3 feet below

the ceiling. If a minimum value of .5 foot-

candle is required at the corner of the room,

we have the equation (first method outlined) :

1 ..1.0 = c. p-

12.8^-X

1 - .5

Since d =i/8' + 8' + 6'

Fig. 53)

_1 9 Q /'see ^'^' ^"* Diagram for Four

'^' ^ 8-c. p. I-amps on

Side Wall.

154

1

<g

>: Q

> sz fa=>

Cfi pouH '^< Qb] »}'

o .ti

%^'

s

<HUo<s

ooKazzo

K o

.. »•a fl

.3

a

>

Q

M

^3oo

O

e

p.<, 3

>-

O -r

a.<zo

-/ a— ^ art

= /. u'^ e<= *^

r!^ a

?^8<

Q

0. «- ,

<

a Aid

n'a•J

J

FLKfTIUr I icMTlvr; gi

Solving the aljovt- for the valm- (»f r. p., we have

c. p.=_ ••'

.5 X H2 =-- 41

Thre<' Uj-euiulU'-jxnver lamps would serve this pur|)ose very

well.

Deteriiiiiiiiifj the illumination directly umlt-r tin- lamj). we have:

()- 1-

..) .ib

2.7 foot-eandles, or five times the value of the illumination at the

corners of the room.

Next consider four 8-oantlle-power lainj)s hxated on the side

walls S feet alx)ve the floor, as .shown in Fij^'.54. Calculating: the

illumination at the center of the room on a plane three feet above

the floor, we have:

^ ^ ^^~8Q

"^"89"

"^"^89

^Hi)'

^ T^Ts'

rf» = 8' + 5- = 04 + 25 = 89

41 S X X 2 = .72 foot-carulles

8!)

The illumination at the ct)rner of the room wouM he-

^ " ^^W^W^ -Mo'

343^

1-..)

= 8(-J- + -7^ ) X 2 = .4") fiH)t-<andles.<S9 .j4.)

In a similar manner tht- illuiuinatit)n may he (-dculattd for any

\H>\ulin the nK)m, or a series of points may Im- taken and curves ploC(c<i

siiowin^ the distribution of the li^'ht. as well as the areas having the

same illumination. Where re(iiu<l calculations are desire<l, the di-«-

trihution curve of the lamp must Ik- usvi\ for determining: the ean<ll«-

jM)Wer in dilFcrcnt ilin-'tions. Kij;. ')') shows illumination curves for

tin- Meridian lamp as manufacture<l l»y the (Icncral Klectric Com-

pativ. 'I'liis is a form of nllector lamj) made in two sizes, 2"> or .'»<>

eandlc-[M)wcr. I''ij:.'>(» ^ives the distribution curves for tin* .'»(>-

(•andli'-powcr unit. Similar incandescent hunps ar*- now Im-imj:

nianufacturi-<l iiv otlicr coi:ipanies.

1&5


Table XIV gives desirable data in connection with the use of

the Meridian lamp.

Fig. 55. IlUmiiuation Curves for a G. E. Meridian Lamp.

TABLE XIV

Illuminating Data for Meridian Lamps

,1 :

' n\c ur.HTiNo

very ar«-mai. ...m,\ .\licii tin- sysU'in i)f illiiniiiiatioii aiitiuLs of this

inetluxl. OiluT iiutliiMis an- «»fteii .simpler and sufiicieutly act-urdte

for practical work.

FiR. 5ft. Distrllnitlon Curve f<»r ii G. K. riO-c. p. Meridian I^iiip.

Dr. T-()ui> Hell gives tlic following in connection with residence

lighting:TABLE XV

Residence Lighting Data

Ruuu

Hall, 15' X 20'.

Lihriiry, 20' X2U'_

Uccfpiioii ri)()in, l.V X 1

Mn-^ic roorii, 20' .< 2.">' . .

DiiiiiiK roDiii, l.V 20' .

Hilliiiril r.M.iii, l.V X 20'.

\'l,Tch

H.Mlr.M)mrt (G), 15' X 15',

X l.V..

Dr.

.S.T

Mailiruiiin.T .1,

Kitrliiii. l.V •

I'iUitrv, 10' XII.'iIIm'^

(Vlliir \

10' X l.V.

lO'Xlo'10' . .

IV (

1.V )

.


LIGHTING OF PUBLIC HALLS, OFFICES, ETC.

Lighting of public halls and other large interiors differs from the

illumination of residences in that there is usually less reflected light,

and, again, the distance of the light sources from the plane of illumi-

nation is generally greater if an artistic arrangement of the lights is

to be brought about. This in turn reduces the direct illumination.

The primary object is, however, as in residence lighting, to producea fairly uniform ground illumination and to superimpose a stronger

illumination where necessary. An illumination of .5 foot-candle for

the ground illumination may be taken as a minimum.

In the lighting of large rooms it is permissible to use larger light

units, such as arc lamps and high candle-power Nernst or incan-

descent units, while for factory lighting and drafting rooms, where

the color of the light is not so essential, the Cooper-Hewitt lamp is

being introduced. High candle-power reflector lamps, such as the

tungsten lamp, are being used to a large extent for offices and drafting

rooms.

The choice of the type of lamp depends on the nature of the

work. Where the lisj;ht must be steadv, incandescent or Nernst

lamps are to be preferred to the arc or vapor lamps, though the latter

are often the more efficient. AMien arcs are used, they must be care-

fully shaded so as to diffuse the light, doing away with the strong

shadows due to portions of the lamp mechanism, and to reduce the

intrinsic brightness. Such shading will be taken up under the head-

ing "Shades and Reflectors." Arcs are sometimes preferable to

incandescent lamps when colored objects are to be illuminated, as in

stores and display windows.

In locating lamps for this class of lighting, much depends on the

nature of the building and on the degree of economy to be observed.

For preliminary determination of the location of groups, or the illumi-

nation when certain arrangement of the units is assumed, the prin-

ciples outlined under "Residence Lighting" may be applied. It has

been found that actual, measurements show results approximating

closely such calculated values.

\Mien arcs are used they should be placed fairly high, twenty

to twenty-five feet when used for general illumination and the ceilings

are high. They should be supplied with reflectors so as to utilize

the light ordinarily thrown upwards. Wlien used for drafting-room

158

I! I'C'IMMC I '( MI'TIW; r-^'i

work, tlu'V slioiihl Ik* susjM'iulnl from twi-lvr to fiftiH-rj feet alxive

the floor, ami s[M-<ial rare inu.st In- taken to tlitTuse the light.

IrieuiKleseeiit latnj)s may Im- arraiifjetl in fjroups, either as side

lij,'hts or inouiitetl on chandeliers, or they may Ije arranged u.s a frieze

running around the HMiin a fiw feet Ix-low the eeiling. The la.st

named arrangement of lights is one that may Ik- made arli>tie, hut it

is uneeonomital and when used should serve for the grouncl illumiiui-

tiou oiilv. Kelleitor lights may he useil fur this style of ui»rk and

the lights may b<' entirely concealed from view, the reflecting prop-

erty of the walls iK'iiig utilized for distrihuting the light where neede<J.

reiling lights should prcfcraMy he supplied with reflectors,

especially when the ceilings are high.

Indirect li'diting is emidoved to some extent. Bv indirect

lii'htin" we mean a svstem af illumination in which the light sources

are coiuealeil and the light from them is reflected to the njom hy the

wal.'s, or ceilings, or other surfaces; or in which the light sources are

plaied above a difVusing panel. In the latter case the diffusing plate

apf ^ars to Ix' the .source of light. In some ca.ses the walls them.selves

are shajx'd ami constructed .so as to form the refliH:tors for the light

uni 5 (cove lighting), hut in others all of the reflecting surfaces, except

the side walls and ceiling, are made portions of the lanij) fixtures.

Tables XVI and X\II give data on arc and mercury-va|x)r

laii|)S

for lighting large rooms. Table XVII refers to arc lights as

ac'Mallv installf<l.

>

<

aEcs

.J

u

<o

Q

G

JS

H O

O2

O B<

•<:

Qa

n

is

o2 a

O

w S

o

> a< ow o

o

o

o tooo oo00

00 *'^ _; b

CI t- ^3 5?"

to CO"'

to

m CI ^G CO

to t^"

ro ^{J

o «< or-> CO

<J< -H -H

in c^-3 0>

to CO Tf S ^Tl* "O ^ CO C3O CO «

CO* I—I^

ob r

3o o SO lO .

to •

00

o o o(M 00IN

COCO

•<K O OCSI 00 CO

CO C)

•a

'

Li

o

o

C) ^

O 1-^

C5 (N oto ^

o * oM 00

oC-J

CI _;

1^ C5 Q,CO "o ,ir

Q5o '-'

o2oo

CO

w oI u to

"3CJ

t^ M O CI

CJ"* _;

CJ C) — Srt CO CO JC"

01 jd O) "^

o Q

O C)uo -<)

CI

C)

SKYLIGHT WORK *

Tlie upper illustration shows the layout of a flat pitched .«kylight whose

curb measures G' — 0* X 7' — 6", tiie run of the rafter or length of the glass being

G' 0* on a horizontal line. Five bars are required, making the glass 15 inches

wide A working section through AB and CD is shown below.

It will be noticed in the section through AR tliat the flashing is locked to

the roofing and flanged around the inside of tiie angle iron construction; over

this the curb of the skylight rests, bolted through the angle iron as shown, tho

bolt being capped and soldered to avoid leakage.

The same construction is used in the section through CI), with tho excep-

tion, that when the flashing cannot be made in one piece, a cross lock is placed

in the manner indicated, over the fireproof blocks.

•The itluiitratiou referred to will bo found oa tho back of Ihia pa^*-

lai

coMSTnucTion drawing aHowiriG layoutOF FLAT .5KYL1GH.T ARD i^lLTMOD OF

FA5TEnin.G FLASamG on AnGLE.mon GOA5TRUGTIOn.

—^1 l£>-shmG,

Condensas-tion'

\T.n<2-.

Secrion i;hrouo,h lov/<s,r

end. of curb A.-S

vSecTion rhrou^hu.pper end of curb

C-D

FOR EXPLANATION OF THIS PROBLEM SEE BACK OF PAGE

SHEET METAL WORK

SKYLIGHT WORK\M»ere formerly skylij^lits were cnmstructe*! from wrod^lit iron

or wood, to-<lav in all the larj^e cities thcv are l»ein;j maderif ^alvaiii/xil

sheet iron anilc«)[)j)er.

Sheet metal skylif^hts, having hy their jieculiar

construction lightness and strength, are superior to inm and woollen

lights; su|)erior to iron lights, inasmuch as there is hardly any exjjan-

sion or contraction of the metal to cause leaks or hreiikage of glass; and

su|)erior to wooden lights, because they are fire, water and condensa-

tion* proof, and being less clumsy, admit more liglu.

^riic small Ix^dy of metal usetl in the construction of the bar and

curb ami the provisions which can be made to carry off the inside con-

densation, make slieet metal skylights superior to all others constructed

from diiferent material.

CONSTRUCTIONThe construction of a slieet metal skylight is a very simple matter,

if the patterns for tlie various

intersections are properly devel-

oped. For example, the bar

shown in Fig. 14.') consists of a

piece of sheet metal having the

rcfjuired stretchout and length,

and bent by .special machinery,or on the regular cornice brake,

into the .shaj)e .shown, which rep-

resents strength an<l rigi<lity with

llicleast amount of weight. .\ A

represent the condensation gut-

ters to receive tlie condensationFig. 1 J.'i. I ig. un.

from the inside when the warm air strikes against t\\v ci>lil surface of

tlie glius.s, while ]\ ]\ shovv the rabbets or glas.s-rest for the glasA.

In Fig. li(j, C C is a re-enforcing strip, which is «imn1 to li(»ld tJic

ih:<

134 SHEET IMETAL WORK

two walls O O together and impart to it great rigidity. When skylight

bars are required to bridge long spans, an internal core is made of

sheet metal and placed as shown at A in Fig. 147, which adds to its

weight-sustaining power. In this figure B B shows the glass laid on

a bed of putty with the metal cap

C C C, resting snugly against the

glass, fastened in position by the

rivet or bolt D D. Wliere a very

large span is to be bridged a bar

similar to that shown in Fig. 148 is

used. A heavy core plate A made

of j-inch thick metal is used, riveted

or bolted to the bar at B and B. In

construction, all the various bars

terminate at the curb shown at A BC in Fig. 149, which is fastened to

Fig- 147. the wooden frame D E.

The condensation gutters C C in the bar b, carry the water into

the internal gutter in the curb at a, thence to the outside through holes

provided for this pm-pose at F F. In Fig. 150 is shown a sectional

view of the construction of a double-pitched

skylight. A shows the ridge bar with a core in

the center and cap attached over the glass. B

shows the cross bar or clip which is used in

large skylights where it is impossible to get the

glass in one length, and where the glass must r"

be protected and leakage prevented by means

of the cross bar, the gutter of which conducts

the water into the gutter of the main bar,

thence outside the curb as before explained.

C is the frame generally made of wood or angle

iron and covered by the metal roofer with flash-

ing as shown at F. D shows the skylight bar

with core showing the glass and cap in position. E is the metal curb

against which the bars terminate, the condensation being let out

through the holes shown.

In constructing pitched skylights having double pitch, or being

hipped, the pitch is usually one-third. In other words it is one-third

164

^uv.KT Mrr\r wmi-k' i::.'

of tlu- >|iiiii.If a .skyliji;ht

weif IL' fet-t wiile ami one-third pitch were

rttiiiirftl. tht> rise in the center wuulil Im.* one-third of 12, or 4 feet.

When 11 Hat .skyHj,'htis made tlie

pitch is usually huilt in the w^hmI

or iron frame anil a flat skylight

laiil over it. The jjlassuse<l in

the construction of metallic .sky-

lijjhts is usually J-inch rough or

rii)l)cd glass; hut in some cases

heavier glass is useil.

If for any rea.st)n it is desired

to know the weight of the various

thickness of glass, the following

table will prove valuable.

NN'eight of Koujrh (Mass Per

Square I out.

Thickness in inches.

i iV i- ^- ^- ^- '• ^-

Weight in |)ounds.2. •2\. 3\. 5. 7. S'.. 10. 12",.

B^Y

FiR. 160.

10»

136 SHEET METAL WORK

SHOP TOOLSIn the smaller shops the bars are cut with the hand shears and

formed up on the ordinary cornice brake. In the larger shops, the

strips required for the bars or curbs are cut on the large squaring

shears, and the miters on the ends of these strips are cut on what is

known as a miter cutter. This machine consists of eight foot presses

on a single table, each press having a different set of dies for the purposeof cutting the various miters on the various bars. The bars are then

formed on what is known as a Drop Press in which the bar can be

formed in two operations to the length of 10 feet.

METHOD EMPLOYED IN OBTAINING THE PATTERNSThe method to be employed in developing the patterns for the

various skylights is by parallel lines. If, however, a dome, conserva-

tory or circular skylight is required, the blanks for the various curbs,

bars, and ventilators, are laid out by the rule given in Sheet Metal

Work, Part IV, under "Circular Work".

VARIOUS SHAPES OF BARS

In addition to the shapes of bars shown in Figs. 145 to 148 in-

clusive, there is shown in Fig. 151 a plain bar without any condensation

gutters, the joint being at A. B B represents the glass resting on the

rabbets of the bar, while C shows another form of cap which covers

Fig. 152. Fig. 153.

the joint between the bar and glass. Fig. 152 gives another form of

bar in which the condensation gutters and bar are formed from one

piece of metal with a locked hidden seam at A. Fig. 153 shows a bar

on which no putty is required when glazing. It wall be noticed that

it is bent from one piece of metal with the seam at A, the glass B B

resting on the combination rabbets and gutters C C. D is the cap

which is fastened by means of the cleat E. These cleats are cut about

^inch wide from soft 14-oz copper, and riveted to the top of the bar

166

•Iirir MI'.TAL WOUK Mil

at F; tlifii a >lot is cut into tin- caii I ) as sluiwii from «t to h in Ki^;. I54;

tlifii the cap is pressed lirmly onto tlie };la.<>! ami the ch-at K tiirne<l

down whicli holds the cap in |M)sition.

When a skvH;;ht is constnictetl in which raising suslies are re-

ijuiretl, as shown in Fig. loo, lialf l>ars arc re<juire<l at the sides A and

B. while the l)ars on each side of tlie sash to he

raise<l are so constructe<l that a water-tight joint

is obtained when closetl. This is shown in Fig.

15<), whicli is an enlarge*! section through A B in

Fig. loo. Thus in Fig. loG, A A represents the

two half bars with condensation gutters as shown,

the locketl .seam taking place at B B. (^ C repre-

.sent the two half bars for the raising sash with the caps D I) attach-

etl to same, as shown, so that when the sash C C is close<l, the caps

Fig. 154.

FiR. 1.55.

1) D cover the jomt between the glass EE and the stationary half

bars. F F are the half caps soldered at a a to the bars C (' which

protect the joints between the gla.ss II 11 and tlic bars C C.

VVRjOlS SliMMIS or CI R lis

In Figs. lo7, I'vS and 1.'>M

are shown a few sha|Hvs of ctirbs

which are usi-tl in c«»nne<'tion

with flat skylights. .\ in Fig.

I.')7 shows the curb for the thret*

sides of a Hat skylight, fornuti in

one|)ii'<'e

with a joint at B. while

C .shows the cap, fastt'tUMl as previously tlescrilM'<l. ".\" .shows the

height at the lower end ^f the Mirb wh'cJi i.s ina<ie ns high lis the

glass i.s thick and allows tJie wuter U> run over. In Fig. LVS, A b

U17

138 SHEET INIETAL WORK

another form of skylight formed in one piece and riveted at B;a shows the height at the lower end. In the previous figures the frame

on which the metal curb rests is of wood, while in Fig. 159 the frame is

Fig. 157. Fig. 158. Fig. 159.

of angle iron shown at A. In tliis case the curb is slightly changedas shown at B ; bent in one piece, and riveted at C. In Figs. 160, 161;

and 162 are shown various shapes of curbs for pitched skylights in

addition to that shown in Fig. 149. A in Fig. 160 shows a curb formed

in one piece from a to & with a condensation hole or tube shown at B.

Fig. 160. Fig. 161. Fig. 162.

In Fig. 161 is shown a slightly modified shape A, with an offset to

rest on the curb at B. AMien a skylight is to be placed over an openingwhose walls are brick, a gutter is usually placed around the wall, as

168

SIIFI-T MKTALWORK 139

sh()\\ni in Fi^'. 102, in which A represents a section of tlie wall on which

a fitter, H, i.s hung, formed from one piece of metal, a.s shown from a

to b to c. On top of this tlie metal curb C is sohlereil, whicli Ls also

fonnetl from one piece with a lot-k seam at /. To stiffen this curb a

wooilen core i<j slippeil inside as shown at I). FrtMu the iasi«le con-

densation gutter / a 14-oz. copjier tube runs through the curb, shown

at d. The condensation from the gutter r in tiic bar, drips into tlie

gutter /,out of tlie tube d, into the main gutter H, from wliich it is c-on-

veyed to tlie outside by a leader.

In Fig. 103 is shown an enlarged section of a raising sash, taken

through C D in Fig. l."). A in Fig. 103 shows the ridge bar, H the

lower curb and C I) the .side .sections of the bars explaine<l in connec-

tion with Fig. loO. K F in h

Fig. 103 shows the upjjcr

frame of the raising sash, fit-

ting onto the half ridjie bar

A. On each raising sash, at

the upper end two hinges II

are riveted at E and I, which

allow the .sash to raise or close

by means of a cord, rod, or

gearings. J K .shows the

lower frame of the sash fitting

over the curb B. Holes are

|)unch'Hl at o to allow the

condensation to escape int«» h,

thence to the outside through TIk. U>3.

('. C)ver the hinge II a hood or cap is placed which prevents

leakage. Fig. KM .shows a .section through .\ H in Fig. 1(17 and rep-

resents a hippe<l skylight having one-third pitch. Hy a skylight of

one-third pitch is meant a skylight whose altitude or height .\ H.isetpnil

to one-third of the .span C I). If the skylight was to have a pitch «if

one-fourth or one-lifth, then the altititde A H would espial oni»-fourth

or one-fifth respectively of the span (

"

O.

The illustration .shows the construction of a hipj)etl .skylight with

ridge ventilat«)r which will be briefly descriln-d. (' 1) is the curb; F. K

the inside ventilator; F F die outside ventilator forming a cap over ihc

iiin

140 SHEET IVIETAL WORK

glass at a. G shows the hood held in position by two cross braces H.J represents a section of the common bar on the rabbets of which the

glass K K rests, L shows the condensation gutters on the bar J,

Fig. 164.

which are notched out as shown at M, thus allowing the drip to enter

the gutter N and discharge through the tube P. The foul air escapesunder the hood G as shown by the arrow.

Fig. 165.

170

I

DORMER ON MUSEE DE CLUNY, PARIS, FRANCEBuilt in the Fifteenth Century Note the Figure Sculpture at Sides of Dormer.

iu

3

I

8 i.

o IT :K r V.

o = az = >

Q - r

S = a

— a

<

t

SIIKKT MK'I'M \\( i!;K HI

\ AkIOtS STYLES Ol >KM.l(im>

In Fi^. H'u) is sluiwii wliat is kimwii as a single-pitdi Itf^lit, and is

plact-ilon :i curl> made In* the car|)C'nter wliicli luis the ilesirnl

jiitcli.

Fig. 160.

'rhe.se.skylislit.s

are chiefly u.setl on .steep rt)of.s a.s .sliown in the ilhi.s-

tration, ami made to .set <>n a \\(MKlen furl).s pitching the .same as the

A

FiR. 107.

roof, the ( iirh first l)eing {la.shctj. \\'ntilation is obtainetl l)y raising

one or more liglits l)y means of gearings, as sliown in Fig. l.V).

FJK. l(i.H.

17 1


Fig. 166 shows a double-pitch skylight. Ventilation is obtained

by placing louvres at each end as shown at A. Fig. 167 shows a

skylight with a ridge ventilator. The corner bar C is called the hip

bar; the small bar D, mitering against the corner bar, is called the jack

bar, while E is called the common bar. Fig. 168 illustrates a hip mon-

itor skylight with glazed opening sashes for ventilation. These sashes

can be opened or closed separately, by means of gearings similar to

those shown in Fig. 177 In Fig. 169 is shown the method of raising

Fig. 169.

sashes in conservatories, greenhouses, etc., the same apparatus being

applicable to both metal and wooden sashes. Fig. 170 shows a view

of a photographer's skylight; if desired, the vertical sashes can be made

to open.

In Fig. 171 is shown a flat extension skylight at the rear of a store

or building. The upper side and ends are flashed into the brick work

and made water-tight with waterproof cement, while the lower side

rests on the rear wall to which it is fastened. In some cases the rear

172

SHEET MirrAI. WORK 143

gutter is of cast iron, put up hy tlir iron workt-r, l)ul it is usuully niiule

of No. 22 pilva!u/,e<l iron, or 2(>-o/.. colil-rolle*! copper. To receive

the lM>ttoin of the jjutter and skylight, tiie wall should he c«»vere<l l»ya

\viK)den plate A, Ki^. 172. al>out two inches tliick. ami another j^lank

.set e<l«^eways flush with the insid*- of the wall, as shown at B. 'I'he

two planks are not re<|uire<l when a cast iron flutter is u.se<l.

Fijj. \7'^ slu)ws a hij)j)ed skyli;;ht without a ridfje ventilator, .set

on a metal curh in which louvres have Keen place<l. These lou\Ttts

tnav he made stationarv or movahle. When made movahle. they are

:

''

Imr. 170.

con.structed as shown in Fij,'. 17 I, in which A .shows a pers|HH'tive view,

|{ shows them closetl, and (

'

open. They are o|)erate«l hy the tpiad-

rants attached to the upri|^ht hars a and h, which in turn are j)uIUn| upand down hy cords or chains work«-d from hclow. ^^hen a skylight

lias a very lonj; spati, as iti Ki^'. 17.">, it is constructeil as shown in Fijj.

17(i, in which .A repres«'nts a T-hcam which ean he tru.vsiNl ifne<t'.s.siiry.

Tliis construction allows the water to cseap<* from the lM)ttom of the

up|MT li^'ht to the outside of the top of the lower skylight, the curh Cof the

iijiper lij^'ht fittinjj over the <'urh H of the lower light.

173


In Fig. 177 is shown the method of applying the gearings Ashows the side view of the metal or wooden sash partly opened, B the

Fig. 171.

end of the main shaft, and C the binder that fastens the main shaft to

the upright or rafter. D shows the quadrant wheel attached to main

shaft and E is the worm wheel, geared to the quadrant D, commun-

icating motion to the whole shaft.

F is a hinged arm fastened to the

main shaft B and hinged to the

sash. By turning the hand-whee 1

the sash can be opened at any

angle.

DEVELOPMENT OF PATTERNSFOR A HIPPED SKYLIGHT

The following illustrations

and text will explain the princi-

ples involved in developing the

patterns for the ventilator, curb,

hip bar, common bar, jack bar,

and cross bar or clip,in a

hipped skylight. These princi-

ples are also applicable to any other form oflight, whether flat,

double-pitch, sing-le-oitch. etc.

174

SHEET METAL WORK 145

In Fi^. 17S is shown a half .se<'tii)n, afjiuirtfr phiii, ami a

iJiiip)naI elevation of a hip har, inthuhnj; the patterns for tl»e curh,

hi|), jack, ami coinnion hars. '^Tlie method of niakinjij tliese drawinpi

will l>e exi)lainetl in detail, so that tlie student wlu) pays close attention

Fig 173

wn'll have no difficnlty in laying out any patterns no matter what the

pitch of tlie skylight may be, or what angle its plan may have.

First draw any center line its A B, at right angles to which lay off

C 4', ef|ual to 12 inches. A.'isuming that the light is to have one-third

FlK. 171.

pitch, tlicn nuike the distaniv CI) e<|Ual to S inches which is on«Mhird

of 21 inches, and <lruw the slant hue 1 > I.' At right angles to I ) I' phurasei'tion of theconnnon l»ar a.s shown l>y K, through which draw lini*s

[larallrlli> 1 )

1'^ intersei'ting the curl) shown fn)m a to / at the Utttoni

and the inside se<'tion of the ventilator fn^ni 1-' to (i at the top. At

\7T>

146 SHEET METAL WXDRK

pleasure draw the section of the outside vent shown from hio I and the

hood shown from mtop. X represents the section of the brace resting

on i j to uphold the hood resting on it in the corner o. The condensa-

Fig. 175.

tion gutters of the common bar E are cut out at the bottom at 5' 6'

which allows the drip to go into the gutter d e f oi the curb and pass

out of the opening indicated by the arrow. Number the corners of

each half of the common bar section E as shown, from 1 to 6 on each

side, through which draw lines

parallel to D 4' until they inter-

sect the curb at the bottom as

shown by similar numbers 1' to

6', and the inside ventilator at the

top by similar figures 1" to 6".

This completes the one half-sec-

tion of the skylight. From this

section the pattern for the com-

mon bar can be obtained without

the plan, as follows:

At right angles to D 4' draw the Una I J upon wliich place the

stretchout of the section E as shown by similar figures on I J. Throughthese small figures, and at right angles to I J, draw lines, and intersect

them by lines drawn at right angles to D 4' from similarly numbered

intersections V to 6' on the curb and 1" to 6" on the inside ventilator.

Trace a line through points thus obtained ; then A* B* C^ D' will be the

Fig. 176.

176

SUKKT MKr.\L \\T)HK 147

piitteriifor the (luninon liar in a

liippeil skvli^jlit. 'I'lie same inetluKi

would l(f employe*! if a pattern were ilevelope*! for u flat or a «loul)le-

pitili li^lit. From this same half section the pattern f«jr the curh is

ilevelope«l l)y takin;^ the stretchout i»f the various corners in tiie curb,

(J h '.V -I' (• il r aiitl/.and |»lacinj^ them on the center line A B as shown

by similar letters and figures. Through these divisions and at rij^ht

angles to A B draw lines which intersect with lines drawn at right

angles to C A' froni similar jKiints in the curl> section aj.

'IVace a line

through points thus obtained; then K' F' / a will he the half pattern for

the curl) shown in the half section. V represents the condensation hole

to he punched into tlie pattern between each light of glass in the sky-

light. As tlie {x)rtion c d turns up on c 4', u.se r as a center, and with

I'^g. 177.

the radius r .v strike the semicircle shown. AI)ove this semicircle

punch the hole \.

Before the patterns can l>e obtained for the hip ami jack bars, a

i|iiarfcr j)lan view nnist Ik- constr\icte<l which will give the jxiints of

intersections between the hip bar and curb, between the hip bar and

vent, or ridge bar, and between the hip and jack bar. Therefore, fnun

any j)oint on the center line .V B as K, draw K 1/ at right angles to A B.

.Vs the skylight forms a right angle in plan, draw from K, at an angleof 4.')°, the hip or iliagonal line K \'\ Take a tra<Mng t»f the ctmunon

bar se<'tion V. with the various figures on same, amij)la<t" it on the hip

line K P in plan >o that the ]Hiin(s I I <"t»me dinn'tlv on the hip as

shown by K'. Through tlic various figures draw lines parallel to K 1°

177

PATTERN FORCOMMON BAR rrCUT FOR UPPER END

OF JACK BAR

1^

Fig. 178.

SlIKirr MK'IAI. WORK IW

or»e-lialf of which are iiiterse<'tt*<l l>y vertical Hne^i tlrawii parallel to AH fn)in similar jHjints of intersection 1' to (5' on the curb, and 1" to 0*

on the ventilator in the half section, as shown res|)ectively in plan by

interse<-tions 1° to ('t° and V to 0''. Helow the hip line K 1° trace the

opposite intersection as shown. It shoulil he untlersto«>d that the

section E' iti ])lan does not indicate the true profile t>f the hip bar

( whichinust heohtained later), hut is only j)lace«I there to give tlie hori-

zontal distances in j)lan. In laying out the work in practice to full size,

the up[)er half intersection of the hip bar in ])lan is all that is ret|uiretl.

It will be noticed that the j)oints of intersections in j)lan and one half

section have similar numbers, and if the student will carefully follow

each point the method of these projections will become apparent.

Having obtained the true j)ointsof intersections in plan the next

step is to obtain a diagonal elevation of the hip bar, from which a true

section of the hip bar and pattern are obtained. To do this draw anyline as R M j)arallel to K 1°. This base line R M has the same eleva-

tion as the base line C 4' has in the half section. From the various

{joints 1° to G° and V to G^' in plan, erect lines at right angles to K 1°

crossing the line R M indefinitely. Now measuring in each and every

instance from the liiu' (

' V in the half section take the various distances

to jM.ints I) 1" 2" 3" 4" .")" and (i" at the top, and to iK)ints 1' 2' 3' 4' ">'

and G' at the biJttom, and place them in the diagonal elevation meas-

uring in each and every instance from the line R M on the similarly

iiumberc<l lines drawn from tlie plan, thus locating respectively the

|X)ints N r 2^ 3^ 4^ ^ and G^ at the top, and 1'' 2'' 3'' 4'" ')• and tr at

tlie l)ottom. Through the points thus obtaine<l draw the miter lines

P to G' and 1'" to G'" and c-onnect tlie various j>oints by lines as .sliown,

which completes the diagonal elevation of the hip bar intersecting the

curb and vent, or ridge. To obtain the true section of the hip bar,

take a tracing of the c<jmmon bar K or K' and place it in the |>osition

shown by Iv\ being careful to j)lace the j)oints 1 4 at right angles to

1' ]' as shown. From the various j)oints in the se<-tion K' at right

Rnglf^ til r r draw lines intersecting similarly munberi'd lines in tlie

<iiagonal elevation as shown from I In •"• mi either siile. ConiUH-t these

jK)ints as shown; then V/ will be the true profileof the hip bar. Note

the di (Terence in the two profiles; the normal l''.' and the modititnl K'.

Having obtaine<| the (rue profile F' the pattern for the hip bar i:«

oiitairnil by drawing the stretchout line O V at right angles 1' 1'.

170


Fake the stretchout of the profile E* and place it on O P as shown bysimilar figures. Through these small figures and at right angles to

O P draw lines which intersect by lines drawn at right angles to 1^ 1^

from similarly numbered points at top and bottom, thus obtaining the

points of intersections shown. A line traced through the points tlius

obtained, as shown by H* J^ K^ L^ will be the pattern for the hip bar.

For the pattern for the jack bar, take a tracing of the section of the

common bar E and place it in the position in plan as shown by E^

being careful to have the points 1 and 4 at right angles to the line 1^ 1°.

It is immaterial how far the section E" is placed from the corner 2° as

the intersection with the hip bar remains the same no matter how far

the section is placed one way or the other. Through the various

corners in the section E- draw lines at right angles to the line 1° 1^ inter-

secting one half of tlae hip bar on similarly numbered lines as shown bythe intersections P2^3'^ 4^ 5^ 6^ and 1^ 2"^ 3-^ 4^ S*' andG'^; also inter-

secting the curb in plan at points 1^ to 6^. The intersection between

the jack bar and curb in plan is not necessary in the development of

the pattern as the lower cut in the pattern for the common bar is the

same as the lower cut in the pattern for the jack bar. However, the

intersection is shown in plan to make a complete drawing. At right

angles to the line of the jack bar in plan, and from the various inter-

sections with the hip bar, erect lines intersecting similarly numbered

lines in the section as shown. Thus from the various intersec-

tions shown from P to 6^ in plan, erect vertical lines intersect-

ing the bar in the half section at points shown from P to 6^. In

similar manner from the various points of intersections 3'', 5"^, and 6"'

in plan, erect lines intersecting the bar in the half section at points

shown by 3"' 5'^ &. Connect these points in the half section, as shown,

which represents the line of joint in the section between the hip and jackbars.

For the pattern for the upper cut of the jack bar, the same stretch-

out can be used as that used for the common bar. Therefore, at rio-ht

angles to D 4' and from the various intersections P 2^ 3'' 4^ 5'' and 6^

draw lines intersecting similar numbered lines in the pattern for the

common bar as shown by similar figures. In similar manner from the

various intersections 3^ 5^ and 6"' in the one half section, draw lines at

right angles to D 4' intersecting similarly numbered lines in the pattern

as shown by 3'^ 5"^ and Q'^. Trace lines from point to point, then the

180

SIIKKT MKTAL WORK 151

cut shown from N' to I" will represt'tit the miter for that part sliown iu

plan from 2'' to G',and the cut shown from I" to ()• in the pattern will

represent the cut for that part shown in plan from 2*- to 0'', Thelower cut of the jack bar remains the same as that shown in the pattern.

The half pattern for the em I nf the hooil is shown in Fij;. 17'.>, ami

is obtained as follows: Draw any vertical line as A H, Ujxjn which

place the stretchout of the section of the hood m n o p in Fij^. 178, as

shown by similar letters m nop on A \'> in Fi{^. 17!>. At right angles

to A B and through tlie small letters draw lines, making them e<jual in

length, (measuring from the line A B) to jM)ints having similar letters

in Fig. 178, also measuring from the center line A B. C'omiect jxjints

shown in Fig. 170, which is the half j)attern for the end nf the hood.

For the half pattern for the end of the outside ventilator, take tJie

Tl

m

HALF PATT El

FOREND OF HOOD

op]

I

J

HALF PATTERNFOR END OFOUTSIDE VENT

2*1

A"HG

B

HALF PATTERNFOR END OFINSIDE VENT

Fig. 179. Fig. ISl.Fig. 180.

stretchout of A/;'

k I in Fig. 17s ami jilace it on the vertical line .\ H in

Fig. ISO as shown by similar letters, tlirough which draw horizontal

lines making them in length, measuring from A H, ecpial t«> similar

letters in Fig. 178, also measuring from the center line .\ H. Connect

the points as shown in Fig. ISO which is the desire<l half pattern. In

Fig. 181 is .shown the half |)attern for the end of Uie inside ventilator,

tlie stretchout of which isobtainetl from F 1" 2" 3" l" II (I in Fig. 17S.

the jjattern l>eing obtained as explained in connection with Figs. 17l)

ami ISO.

When a skylight is to be constructed on which the bars are of such

lengths that tlic glass cannot be obtained in one length, and n cross bar

or clip is re<jnia«d as shown by B, in I'ig. l.*)(), which miters against the

main bar, thej)attern

fnr this intersecting cut is obtaineil as shown in

181


Fig. 182. Let A represent the section of the main bar, B the elevation

of the cross bar, and C its section. Note how this cross bar is bent so

that the water follows the direction of the arrow, causing no leaks be-

cause the upper glass a is bedded in putty, while the lower light b is

capped by the top flange of the bar C (See Fig. 150). Number all of

the comers of the section C as shown, from 1 to 8, from which points

draw horizontal lines cutting the main bar A at points 1 to 8 as shown

At right angles to the lines in B draw the vertical line D E upon which

1 2

8-_Z^^

3 4C

13";

PATTERN FORCROSS BAR

e"i

E

Fig. 182.

place the stretchout of the cross bar C, shown by similar figures,

through which draw horizontal lines, intersecting them with Unes

drawn parallel to D E from similar numbered intersections against the

main bar A, thus obtaining the points of intersections 1' to 8' in the

pattern. Trace a line through points of intersections thus obtained

which will be the pattern for the end cut of the cross bar.

In Fig. 183 is shown a carefully drawn working section of the

turret sash shown in Fig. 168 at A. These sashes are operated by

182

SHEET METAI. ^VOI{K VA

I

1 In °1.^

means of ct>rds, chains or gearings from the insitle, the pjvot on which

thev turn l>eing shown hy 11 S in Fig. 1S3. Tlie method of obtaining

tlie patterns for these saslies will l>e omittwl, as they are only stjuare and

htitt miters which tlie student will have n-* trouble in developing, pro-

vitling he understamls the construe-

tion. This will \>e mmle clear hy

the following explanation:

A B represents the ujiper part of

tlie turret proper with a drip bent on

same, as shown at B, against which

the sashes close, and a double seam,

as shown at A. which makes a tight

joint, takes out the twist in bending,

and avoids any soldering. This up-

per part A B is indicated by f'

in

Fig. 1G.S, over which the gutter B is

placed as shown by X U Y in Fig.

183. C. D represents the lower part

of tlie turret proper or base, which

fits over tlie wooden curb W, and is

indicated by D in Fig. lOS. E in

Fig. 183 represents the muUion

made from one piece of metal ami

double seaiiie<l at o. This mullion

is joine<l to the top and bcttom.

'Hie pattern for the top end of the

midlion wtjuld simj)ly show a square

cut, wliile tlie j)atternfor the bot-

tom wouM represent a butt miter

against the slant line ij.

Before forming up this mullion the holes

shoulil be punched in the sides to admit the j)ivotU .'^. These mullit»ns

are shown in position in Fig. KJS bv E I'^., etc

V ( I in Fig. 1S;.3 represents the .section of tlie side of the sash Ih>Iow

the j)ivot T. Notice that tliis lower half of tlie siile of tlie siush has a

lork attachment which h(X)ks into the flange of the mullion E at F.

While the .side of tlie sash is bent in one piecx;,the uj)j>cr half, alxive the

|)ivot T, hiLS the lock omitted as shcwti by .1 K. 'llius when tiie ."MLsh

((pens, the uj»per half of the sides turn toward Uie inside lus .shown by

lua_-.

H

'r

V.

-i)^

FiK. 1S.1.

IH.<


the arrow at the top, while the lower half swings outward as shown by

the arrow at the bottom. When the lower half closes, it locks as shown

at F, which makes a water-tight joint; but to obtain a water-tight joint

for the upper half, a cap is used, partly shown by L IVI, into which the

upper half of the side of the sash closes as shown at M. This cap is

fastened to the upper part of the mullion E with a projecting hood /

which is placed at the same angle as the sash will have when it is

opened as shown by e e' and d cV or by the dotted lines.

The side of the sash just explained is shown in Fig. 168 at H.

The pattern for the side of the sash has a square cut at the top, mitering

with H I at the bottom, in Fig. 183, the same as a square miter. H I

represents the section of the bottom of the sash. Note where the metal

is doubled as at h, against which the glass rests in line with the rabbet

on the side of the sash. A beaded edge is showTi at H which stiffens it.

This lower .section is shown in Fig. 168 by G and has square cuts on

both ends. N O in Fig. 183 shows the section of the top of the sash

shown in Fig. 168 by F. The flange N in Fig. 183 is flush with the out-

side of the glass, thereby allowing

the glass to slide into the grooves

in the sides of the sash. After the

glass is in position the angle P is

tacked at n. A leader is attached

to the gutter Y as shown by B° in

Fig. 168. While the method of

construction shown in Fig. 183 is

generally employed, each shop^^' '

has different methods; what we

have aimed to give is the general construction in use, after knowing

which, the student can plan his own construction to suit the conditions

which are apt to arise.

In the following illustrations. Figs. 184 to 187, it will be explained

how to obtain the true lengths of the ventilator, ridge, hip, jack, and

common bars in a hipped skylight, no matter what size the skylight

may be. Using this rule only one set of patterns are required, as for

example, those developed in connection with Figs. 178, 179, 180, and

181, which in this case has one-third pitch. If, however, a skylight

was required whose pitch was different than one-third, a new set of

patterns would have to be developed, to which the rule above mention-

IE 11 10

184

e<l woulil also be iipplicaltlc for .skyli^lits nf tlmt particular pitcli.

Using tliis rule it sliould l)c unclt'rst«M)d tliat tlie size of the curb, or

frame, forms tlie basis fur all mejisuremeiits, and that rme of the lines

or l)endsoftlie barshoulil meet the line of the curb as shown in Fig. 17K,

where tlie bottom of the bar K in the half section meets the line of the

curb c 4' at 4', and the ri<li:e at the top at 4'. Therefore when laying

B

K^ 10^

i>nhiiliiililil.ii l.iilii.l.iil.i.l.i.Li^1r>>^12 11 10 9 6 7 6 5 -^ 3 2 1

Fig. 185.

out the lengths of the bars, they would have to be measured on the line

4 of the l)ar E from 4' to 4" on the patterns, as will be e.xplaineil as we

proceed.

The first step is to prepare the triangles from wliich the lengths

of the common and jack bars are ol)taine(l, also the lengths of the hip

bars. After the drawings and j)atterns have been laid out full si/e

according to the principles explaineil in Fig. ITS, take a tracing of the

triangle in the half section 1) C 4' and place it as shown by A 12 O, in

Fig. IM. Divid.- () IJ, which

will be 12 inches in full size, into

(piarter, half-inches, and inches,

the same as on a 2-foot rule, as

shown by the figures C) to 12.

From these divisu)ns erect lines

until they intersect the pitch .\ ( )

which cMm|iletes the triangle for

• tbtaiiiing the true lengths of jackand conunon bars for anv size skvliirht. In similar manner take

tracing >>( X 1! I' in the diagonal elevation in Fig. I7s and

j»lac«'it as shown by H 12 () in Fig. 1S.'». The length 12 O tlien

iM'comes the base nf tin* triangle for the hip bar in a skvlight whose

ba-ic of ili<-trI;iiigU> for tlie connnon and jack i)ars meiusure.s 12 inches

a'-o'-d

X


\

THE "NASSAUER HAUS " IN NURNBERG, GERMANYBuilt at the End of the Thirteenth Century. Railing of Gallery underneath Red-Tiled Roof is

Decorated with Coats of Arms. In the Niche over the Fountain at theIvower Right, is a Statue of King Adolf von Nassau.

i

'^r^.

^ii

A

TERRACE OK HOUSE AT MONTECITO. CALIFORNIA

Myrou Hiiiil .11: Kliiu-r lin-}-, Archltcitx, Lkk Aut:<'l<^!*' *-'•''

For IVr<iii«cllvo View of IlulldlDtf. Sr<i Pasp SOS: niiirniPUt, Klrnt, and Src«iuil Kloor I'lan* Shownon I'n^v

^

SIIKKT MinWI. Work

est sitle of frame) -r- 2 =- 2 feet. We have now the leiij^th witli whicli

to j)rocee<l to tlie triaiij^le for (>oiiiiiioii and hip Imrs. ThiLS the len^tii

of the eominon har c d will l»ee<|iial to twice the amount ^A A ( ) in Fij;.

1x4, while the length of tlu-liip liar i> e in V\^. IS*), will l)e njual to twice

the amount of H () in Fij;. ISo. Referrinj; to Fif;.s. isfi and Is? the

jack bars /yare spact**! Iti inches, therefore, the length of tlie jack bar

for 12 inches will e<|ual A ( ) in Fijj. 1S4, and 4 inches e<|ual to 4° ();

botl) of which are adde<l together for the full length.

The lengths of the common and hip bars will be .shorter in Fig.

187 because a ventilator has been used, while in Fig. ISO a ridge bar

was employe) 1. To obtain the lengths of the common and hip bars in

Fig. 187 use Rule 3: 4S inche.s (length of short side)— 4 inches (widtii

of inside ventilator)^ 44 inches; and 44 inches -r- 2 =22 inches or

1 foot 10 inches. Then the length of the conunon bar c' d' mea-sure<l

with a rule will be e<|ual to A <) in Fig. 1S4 and 10° () atldetl together,

and the length of the hip l)ar v'}'

in Fig. Is7 will be e<jual to H O in Fig.

I80 and 10*0 added together. Use the same method where fraction-

al parts of an inch occur. In laying out the patterns

according to these measurements use the cuts .shown

in Figs. 17S, 179, ISO, and ISl, being careful t«»

measure from thearrowpoints shown on each j)atteni.

It will be iKJticed in Fig. 17s wc always mea.s-

urc on line 4 in the j)atterns for theliij), connnon,

and jack bars. Tins is done l)ecause the line 4 in

the j»rofiles K and F* come directly on the .slant line

of the triangles which were traced to Figs. 1S4 and

\X'> and from which the true lengths were obtained.

WluTc a curb might be us«'d, as shown inl*'ig. ISS,

which would bring the bottom line of the bar ]\

inches toward the inside of the frame h, all around, then insteaci of

using the size «tf 4 x S feet as the basis of measurements deduct .{

inches on each side, nuiking the basis of measuremeiMs ."? ft. '.• inches

.\ 7 ft. '.» inclies, and j)rocee<l as e.\plaine<l al»ove.

TiR. ISS.

1H7


ROOFINGA good metal covering on a roof is as important as a good foun-

dation. There are various materials used for this purpose such as terne

plate or what is commonly called roofing tin. The rigid body, or the

base of roofing tin, consists of thin sheets of steel (black plates) that

are coated with an alloy of tin and lead. AVhere a first-class job is

desired soft and cold rolled copper should be used. The soft copperis generally used for cap flashing and allows itself to be dressed down

well after the base flashing is in position. The cold-rolled or hard cop-

per is used for the roof coverings. In some cases galvanized sheet iron

or steel is employed. No matter whether tin, galvanized iron, or

copper is employed the method of construction is the same, and will

be explained as we proceed.

Another form of roofing is known as corrugated iron roofing,

which consists of black or galvanized sheets, corrugated so as to secure

strength and stiffness. Roofs having less than one-third pitch should

be covered by what is knowm as flat-seam roofing, and should be cover-

ed (when tin or copper is used) with sheets 10 x 14 inches in size rather

than with sheets 14 x 20 inches, because the larger number of seams

stiffens the surface and prevents the rattling of the tin in stormyweather. Steep roofs should be covered by what is known as standing-

seam roofing made from 14" x 20" tin or from 20" x 28". Before anymetal is placed on a roof the roofer should see that the sheathing beards

are well seasoned, dry and free from knots and nailed close together.

Beforelayingthe tin plate a good building paper, free from acid, should

be laid on the sheathing,or the tin plate should be painted on the under-

side before laying. Corrugated iron is used for roofs and sides of

buildings. It is usually laid directly upon the purlins in roofs, and

held in place by means of clips of hoop iron, which encircle the purlins

and are riveted to the corrugated iron about 12 inches apart. Themethod of constructing flat and double-seam roofing, also corrugated

iron coverings, will be explained as we proceed.

TABLES

The following tables will prove useful in figuring the quantity of

material required to cover a given number of square feet.

188

SIIEtrr METAL WORK l.VJ

FL.Vr-.SEA.M H()<)FI.\'(i

Table showing quantity of H x 20-ineh tin rccjuircil to cover a given' ...

»ii» Hjofing. A 8ln-it of II X .' ll

. fclgi'<l or folilid, 13 X I'j i: ^ iV

M|uare inches. In tl>e following all fractiontil jMirtii of a sheet arc counted a

full"

mil

wit

^

^

160 SHEET ISIETAL WORK

STANDING-SEAM ROOFINGTable showing the quantity of 20 X 28-inch tin in boxes, and sheets

required to lay any given standing-seam roof.

SQ. FEET

SIIKKT MKTAI. WoUK ir.l

NKT WKKWIT I'KU BOX TIN PLATES]'.x. tl>. 'm 8B ,90 » lOU'

luT

Sl«« r.f


OTHER FORMS OF METAL ROOFING

There is another form of roofing known as metal slates and shin-

gles, pressed in various geometrical designs with water-tight lock attach-

ments so that no solder is required in

laying the roof. Fig. 189 shows the

general shape of these metal shingles

which are made from tin, galvanized

iron, and copper, the dots a a a a

representing the holes for nailing to

the wood sheathing. In Fig. 190, Arepresents the side lock, showing the

first operation in laying the metal slate

or shingle on a roof, a representing the

nail. B, in the same figure, shows the

metal slate or shingle in position cover-

ing the nail b, the valley c of the bottom

^'s- ^8^' slate allowing the water, if any, to

flow over the next lower slate as in A in Fig. 189.

In Fig. 191 is shown the bottom slate A covered by the top slate B,

the ridges a a a keeping the water from

backing up. Fig. 192 shows the style of

roof on which these shingles are employed,that is, on steep roofs. Note the con-

struction of the ridge roll, A and B in

Fig. 192, which is first nailed in position

at a a etc., after which the shingles B are

slipped under the lock c. Fig. 193 shows

a roll hip covering which is laid from the ^^S- 190-

top downward, the lower end of the hip having a projection piece for

nailing at a, over which the top end of the next piece is inserted, thus

5HEATH/NG BOAR D IJpl

SHEATHING BOARDjSb

%

Fig, 191.

covering and concealing the nails. Fig. 194 represents a perspective

view of a valley with metal slates, showing how the slates A are

locked to the fold in the valley B. There are many other forms of

192

RHKI-n^ MriWL WORK 163

•netiil sliiii^'les, hut tlie shapes shown herewitli ure known as tlie

Cortright patents.

TOOLS RI:QI IRHD

Fig. 195 shows the various hand tools re<[ulre«l hy the metal roof-

er; starting at the left we have the soldering copper, mallet, scraj>er,

A^-,

B

21

ImK. 192.

stretch-awl, .shears, hammer, aiul dividers. In addition to these hand

tools a notching maciiine is retpiired for cutting ofT the corners of the

1 ii;. ]'.»:{.

sheets, and r<M)(ing folders are re-

(piired for e<lging the sheets in llat-

seam roofing, and hand double seamer

and r(X)fing tongs for standing-seam

roofing. Tiic roofing doul)le seamer

and s(|ueezing tongs can he uso»l ft>r

standing-seam roofing (in plaiv of the

hanil diiiilile seamer), which allow the

operator to .stand in an iipright jM)sitionif the ri>of is not to«» steep.

ROOr Mi:\SlR\TI()\

While .some mechanics imdiTsiand tlion»ughly llie metltods of

I'JK. lai.

i03


laying the various kinds of roofing, there are some, however, who do

not understand how to figure from architects' or scale drawings the

amount of material required to cover a given surface in a flat, irregular

shaped, or hipped roof. The modern house with its gables and va-

i

6'0'

tia

ed

Fig. 195.

rious intersecting roofs, forming hips and valleys, render it necessary to

give a short chapter on roof measurement. In Figs. 196 to 198 in-

clusive are shown respectively the plans with full size measurements

for a flat, irregular,and intersected hipped roof, showing how the length

of the hips and valleys are obtained direct from

the architects' scale drawings.

The illustrations shown herewith are not

drawn to a scale as architects' drawings will be,

but the measurements on the diagrams are as-

sumed, which will clearly show the principles

which must be applied when figuring from scale

drawings. Assuming that the plans from which

we are figuring are drawn to a quarter-inch scale,

then when measurements are taken, every quarter

inch represents one foot. ^ inch = 6 inches, ^^

inch = 3 inches, etc. If the drawings were drawn to a half-inch

scale, then \ inch = 12 inches, \ inch = 6 inches, \ inch = 3 inches,

yg inch = I2 inches, etc.

A B C D in Fig. 196 represents a flat roof with a shaft at one side

as shown hy ab c d. In a roof of this kind we will figure it as if there

was no air shaft at all. Thus 64 feet X 42 feet = 2,688 square feet.

The shaft is 12.5 X 6 feet = 75 square feet; then 2,688 feet - 75 feet =

- A2-0"—Fig. 196.

194

SHEET METAL WORK 1G3

X-^

9^

X

O

2,613 s<iuare fct-t of r»H)lii4i;. ti) wlikh must l>e uiitlwl iiii allowaiife for

tlie flosliinj; turning up against an<l into the walls at tlie sides.

In Fig. 107 is shown a flat ronf with a shaft at each sitle, one shaft

iH'ing irreguhir, forming an irreguhir sliape*! ^ ^

roof. The rule for ol)tainuig the area is sim-

ilar to that useil for Fig. 10<) with the exception

that the area of the irregular shaft .r x x x in

Fig. 197 is deterinineil differently to that of the

sluift hcde. Thus .\ H C 1) = lOS feet K 4.')

feet = 4,S()0 sfjuare feet. Find the area of h c

d e which is 9.25 • 39..^ - 3G5.373 or 3(l.^>g

scpiare feet. To find the area of the irregular

sliaft, bisect xx and .r.r and ohtain a a,

measure the length of a a which is 4S feet, and

multiply by 9. Thus 48 X 9 = 412, an.l 412

-}- 365.375 = 777.M75. The entire roof minus

the shafts - \,s{'A) square feet — 777.'S7o =

4,aS2.G25 .sf|uare feet of surface in Fig. 197. ^^'K- '•'"•

In Fig. 198 is .shown the plan, front, and side elevations of an in-

tersected hipped roof. .\ H (' 1 ) represents thej)lan

of the main build-

oc b .'

o

d et* 1. 1

9-3

A 5-0"

_1JC

SIDEELEVATION

lie 1«»S

ing intersecte<l by the wing 1'' F < i II. We will first figure the main

roof as if tlierc were no wing attaclml an<l then dinluct the sputY luken

ins

166 SHEET METAL \WRK

up by the intersection of the wing. While it may appear difficult to

some to figure the quantities in a hipped roof, it is very simple, if the

rule is understood. As the pitch of the roof is equal on four sides the

length of the rafter shown from O to N in front elevation represents

the true length of the pitch on each side. The length of the building

at the eave is 90 feet and the length of the ridge 4S feet. Take

90 - 48 = 42, and 42 ^ 2 = 21. Now either add 21 to the length of the

edge or deduct 21 from the length of the eave, which gives 69 feet as

shown from S to T. The length of the eave at the end is 42 feet and

it runs to an apex at J. Then take 42 feet -^ 2 = 21, as shown from Tto U. If desired the hip lines A I, J B and J C can be bisected, obtain-

ing respectively the points S, T, and U, which when measured will be

of similar sizes; 69 feet and 21 feet. As the length of the rafter O Nis 30 feet, then multiply as follows: 69 X 30 = 2070. 21 X 30 = 630.

Then 630 + 2,070 = 2,700, and multiplying by 2 (for opposite sides)

gives 5,400 square feet or 54 squares of roofing for the main building.

From this amount deduct the intersection E L F in the plan as follows:

The width of the wing is 24 feet 6 inches and it intersects the main

roof as shown at E L F. Bisect E L and L F and obtain pointsW and

V, which when measured will be 12 feet 3 inches or one half of HG,24 feet 6 inches. The wing intersects the main roof from Y to F' in the

side elevation, a distance of 18 feet. Then take 18 X 12.25 = 220.5.

Deduct 220.5 from 5400 = 5,179.5. The wing measures 33 feet 6

inches at the ridge L M, and 21 feet 6 inches at the eave F G, thus

making the distance from V to X =27 feet 6 inches. The length of

the rafter of the wing is shown in front elevation by P R, and is 18 feet.

Then 18 X 27.5 = 495, and multiplying by 2 (for opposite side), gives

995 sq. ft. in the wing. We then have a rooting area of 5,179.5 square

feet in the main roof and 995 square feet in the wing, making a total of

6,174.5 square feet in the plan shown in Fig. 198.

If it is desired to know the quantity of ridge, hips, and valleys in

tlie roof, the following method is used. The ridge can be taken from

the plans by adding 48' + 33'6" = 81' - 6". For the true length of

the hip I D in the plan, drop a vertical line from I' in the front elevation

until it intersects the eave line 1°. On the eave line e.xtended, place the

distance I D in the plan as shown from 1° to D° and draw a line from

D° to I* which will be the true length of the hip I D in the plan. Multi-

ply this length by 4, which will give the amount of ridge capping re-

196

SHEET MirrAL WORK lo:

(luiinl. This lengtli «»fliij)

tan also Ik* obtaiiietl from tlie plan by tak-

ing the vertical hcij,'ht of the roof 1° I' in the elevation and placing it at

right angles to I D in the plan, as shown, from I to P, and draw a lint-

from I- to D which is the desired length.

For tlie length of the valley L F in tlie plan, drop a vertical line

from F' in the side elevation until it intersects the eave line at F°.

Take the distanc"e F L in tlie plan and j)lace it ils shown from F° to L°,

and draw a line from T^° to F*, which is the true length of tlie valley

shown hy L F in the plan. Multiply this length by 2, which will give

tlie retjuireil nund>er of feet of valley retpiired. This length of valley

can also be obtaine<l fi*om the {)lan by taking the vertical height of tlie

roof of the wing, shown by I'^ F* in the side elevation, and placing it at

right angles to F L in tlie plan, from I^ Ut P, ami draw a line from Pto F which is the desired length similar lo F' L° in tht; side elevati<ni.

ri.AT-SEAM ROOFING

The lirst step necessary in jjreparing the plates for dat scam

iHHifing is to notch or cut off the four corners of the plate as shown in

Fig. 1!>0 which .shows the plate as it is taken from the \)ox, the shawled

corners a a a a representing the ctjniers which are ^notchetl on the notching machine or with the shears.

Care mu.st be taken when cutting oil' the.se corners not

to cut off too little otherwise tlie sheets will not edce

well, and not to cut off too much, otherwi.se a hole will

show at tlie corners when the sheets are laid. To fiiul

the correct amount to be cut off proceed us follows: **'

.\ssuming that a l-inch e<lge is ilesireil, set the dividers at \ inch

an<l .scribe the linens h a and « c on the .sheet .shown in Fig. 100, ami,

where the lines intersect at a, draw the line d c at an angle of 45 dt^rees,

which reprasents the true amount and true angle to be

cut off on each corner. After all the sheets have been

notchetl, they are etlged as shown in Fig. 20(), tlie long

sidesof the .sheet being bent right and left, tis shown at

a, while the short sitle is bent as .shown at b, makingthe notched corner aj)pear lus at c. In .some CJises

after the .sheets are edg«tl the contract retpiires that the

sheets 1)«;piiintetl

on the underside before laying. This is usuallv

d«)ne with a small bru.sh. bring careful that tlic etlges of the .sheets

^"

168 SHEET METAL \TORK

are not soiled with paint, which would interfere with soldering. Be-

fore laying the sheets the roof boards are sometimes covered with an

oil or rosin-sized paoer to prevent the moisture or fumes from below

from rusting the tin on the underside. As before mentioned, the same

method used for laying tin roofing would be applicable for laying

copper roofing, with the exception that the copper sheets would

have to be tinned about 1^ inches around the edges of the sheets

after they are notched, and before they are edged.

In Fig. 201 is shown how a tin roof is started and the sheets laid

when a gutter is used at the eaves with a fire wall at the side. A repre-

Fig. 201.

sents a galvanized iron gutter with a portion of it lapping on the roof,

with a lock at C. In hanging the gutter it is flashed against the fire

wall at J ; after which the base flashing D D is put in position, flashing

out on the roof at E, with a lock at F. Where the base flashing Emiters with the flange of the gutter B it is joined as shown at b, allowingthe flange E of the base flashing as shown by the dotted line a. As the

water discharges at G, the sheets are laid in the direction of the arrow

H, placing the nails at least G inches apart, always starting to nail at

the butt e e, etc. Care should be taken when nailing that the nail heads

are well covered by the edges, as shown in W, by a. Over the base

flashing D D J the cap flashing L is placed, allowing it to go into the

wall as at O.

198

SHKKT MKTAL WOHK mi

Wlifiijiiittiiij^

ill l)ii.se (lashings tliere are two iiiftluMis eiii|iluve(l.

Ill Fig. 202 is shown a side thtshiiig hetweeii the roof ami j»araj>etwall.

A sh«)ws the fhishing turning out on the nwjf at H, with a lock C, uttach-

e<l and flashtnl into the wall four courses of hrick al>ove the rtxjf line,

as shown at I), where wall hooks and. -^^

paintskins or roofer's cement are usetl to

make a tight joint. Flashings of this

kind shoiiltl always be i)ainte<lon the

underside, and paper slujiild lie j)la(ed

l)etween the brick work and metal, be-

cause the moisture in the wall is apt to

rust the tin. This method of putting in

flashing is not advisable in new work,

l>ecause when the l)iiil«lingis new, the walls and beams are liable

to settle and when this occurs the flange D tears out of the wall, and tlie

result is disagreeable leaks that stain the walls. When a new roof is

to be placed on an old building where the walls and ctipings are in

place and the brick work and beams have .settled, there is not so much

danger of leakage.

Tlie proper metliod of putting in flashings and one which allows

for the expansion and contraction of the metal and the settlement of tlie

building is shown in Fig. 203, in which A shows the cap flashings,

I'ifi. 20J.

painted with two coats of paint bcfon* using. When the ma.s4in has

built his wall up to four courses of brick iibovc the roof line the ca|>

flashing .\. is j)laced in j>osition anil the wall and ct>])ing finislutl; the

base fhisiiing H is then .slipjx-duiuler the cap .\. In |>racticc the cap

(lashing is cut 7 inches, then bent at right angles through the «t*nter.

making each .side (t and h 'i' inclcs. Tlic l»ase flashing H is then

tlipp«-dunder the cap flashing A a.N shown at (\

1110


Where the cost is not considered and a good job is desired, it is

better to use sheet lead cap flashings in place of tin. They last longer,

do not rust, and can be dressed down well to lay tight onto the base

flashings. Into the lock C the sheets are attached. After the sheets

are laid the seams are flattened down well by means of a heavy mallet,

with slightly convex faces, after which the roof

is readv for soldering. When a base flashing

is required on a roof which abuts against a wall

composed of clap boards or shingles as shown

in Fig. 204, then, after the last course of tin AFig. 205.

j^g^g been laid, the flashing B with the lock a is

locked into the course A and extends the required distance under the

boards D. The flashing should always be painted and allowed to drybefore it is placed in position. In the previous figures it was shown

P"b

how the sheets are edged, both sides being edged right and left. In

Fig

Fig. 206.

205 is shown what is known

as a valley sheet, where the short

sides are edged both one way, as

shown at a a, and the long sides

right and left as shown at bb.

Sheets of this kind are used when

the water runs together from two

directions as shown by A in Fig.

206. By having the locks a and a turned one way the roof is laid in

both directions.

Fig. 207 shows a part plan of a roof and chimney A, around which

the flashing B C D E is to be placed, and explains how the corners Cand D are double seamed,

whether on a chimney,

bulkhead, or any other ob-

ject on a roof when thewater flows in the direction

of the arrow F. The first

operation is shown at a and

the final operation at b.

Thus it will be seen that the water flows past the seam and not againstit. In laying flat seam roofing especially when copper is used, allow-

ance must be made for the expansion and contraction of the sheets.

Fig. 207.

200

SIIERT MKTAL WOUK 171

Care should l)c taken not to nail «lirectly tlir«>Uf,'h the sheet as is shown

ill \V. Fi},'. 201. Wliilf this method is j^eneraliy employed in tin

r<H)Hn<;, on a g«H)d joh, as wt-ll as onc«j[)|)er nx)ling, cleats as shown at

I) in Fij;. 2()S should he tised.

To show how they are used, A and H represent two locked-etlged

sheets. The lock tm the cleat D is locke<l into the e<lf,'e of tlie sheets

and nailed into the roof boards at ii b c and d, ar as often as retjuired.

b

1^d

B

D

Fig. 2(is.

In this maimer the entire njuf can he fastene<l with cleats without

havin«; a nail driven into tlie sheets, thereby allowing for expansion

and contraction of the metal. The closer these cleats are placed, tlie

firmer the roof will be and the better the seams will hold. By using

fewer cleats, time may be .saved in laying the rt)of, but double this time

is lost when soldering the seams, for the heat of the soUiering copper

Imk. JO".).

will raise the .seams, causing a succession of buckles, which retard

.S4>ldering ami re<(uire 10[)er

cent more .solder. When the seams are

luiiled or cleaite<l clo.se it lays flat and smcwith and the soldering is ilone

with ease and less soliler.

When a connci-tion is to be made between metal and stone or

terra cotta, the method .shown in Fig. 2(K) is employnl. This illus

tration .shows a stone or terracotta cornice A. The heavy line ah c d

201


represents the gutter lining, which is usually made from 20-oz. cold-

rolled copper. If the cornice A is of stone, the stone cutter cuts a

raggle into the top of the cornice A as at B, dove-tail in shape, after

which the lining abcdis put in position as shown. Then, being care-

ful that there is no water or moisture in the raggle B, molten lead is

poured into the raggle and after it is cooled it is dressed down well with

the caulking chisel and hammer.

By having the dove-tail cut, the lead is secured firmly in position,

holding down the edge of the lining and making a tight joint. Should

the cornice be of terra cotta this raggle is cut into the clay before it is

baked in the ovens. This method of making connection between

Fig. 210.

metal and stone is the same no matter whether a gutter or upright wall

is to be flashed. WTien a flashing between a stone wall and roof is to

be made tight, then instead of using molten lead, cakes of lead are cast

in molds made for this purpose, about 12 inches long, and these are

driven into the raggle B as shown in Fig. 209 at X.

The most important step in roofing is the soldering. The style of

soldering copper employed is shown in Fig. 210 and weighs at least 8

pounds to the pair. WTien rosin is used as a flux, it is also employedin tinning the coppers, but when acid is used as a flux for soldering zmc

or galvanized iron, salammoniac is used for tinning the coppers. It

will be noticed that the soldering coppers are forged square at the ends,

and have a groove filed in one side as shown at A. When the copperis turned upward the groove should be filed

toward the lower side within J inch from

the corner, so that when the groove is placed

upon the seam, as shown in Fig. 211, it acts

^*g- 211- as a guide to the copper as the latter is

drawn along the seam. The groove a being in the position shown,

the largest heated surface b rests directly on the seam, "soaking"

it thoroughly with solder. As the heat draws the solder between

the locks, about 6 pounds of ^ and h solder are required for 100 square

feet of surface using 14 x 20-inch tin The u^e of acid in soldering

seams in a tin roof is to be avoided fta acid foming m contact with the

202

Ml. - COCYAftC'lTC^

r 1i' Kj t z. - '\^«i r.*^

^.-.-r-f'iT

PLANS OK MODSF. AT MONTECITO. ( Al.IFORNIA

Myri>ii Hunt K Kliiior (>r«}'. AroUII<H-U, I.011 Autfrlp*. c'«L

SlIKI-rr MKTAI. WOUK 173

lijire ed^'es and corners, where tlie slieeLs are fol«le<l ami seametl t«>-

jjetlier, will cause rusting. No other soldering Hux but go«jd clean

rosin shotild he employe*!. The sune flux (rosin) sliould l>e use<l

when soldering copper n^ofing whose edges have previously been

tinned with rosin.

We will now consider the soldering of upright seams. The solder-

ing copjier to l>e emj)love«l for this purj)ose is shaj>e<l as shown in Fig.

212. It is forge<l to a wedge shaj>e, alxnit 1 inch wide and \ inch

3-Fig. 212.

thick at the end, and is tinned on one side and the end only; if tinned

othersvise, tlie .solder, instead of remaining on the tinned side when

soldering, would flow downward; hy having the soldering copper tin-

iie<l on one side only, tlie remaining sides are black and do not tend

t ) draw tlie solder downward. The soldering c^)pper being tlius pre-

paretl, tlie upright seam, shown in Fig. 21.?, where the .sheet R overlaps

the .sheet A 1", is soldered by first tacking the seam to make it lay close,

then tlioroughly soaking the .seam,

an<l tlien placing ridges of solder

across it to strengthen the same.

In using the soldering copper it

should be held in the position )-

shown l)y C, wliidi allows the sol- y" ^der to flow forward and into the

seam, while if the c-opper were held

a.s shown by D, the solder would

flow backward and away from the

seam. In ".soaking" the .seam with

solder tlie copper should be place<l

directly over the lapj)eil part, so that the metal gets tlioroughly

heated and draws tlie .solder between the joint. It makes no dilTer-

vl\(^' where this cross joint o<curs; the same methods are usctl.

The riM.f being comj)leteil, the rosin is si-rajHtloiT the .seams ami

tlier(M)f cleaiie<l and painted with good iron oxide aiitl linseetl oil paint.

.Some roofers omit the s<Ti[)ing of rosin nnd paint dirwtly over it.

Tliia is the cau.se «)f rusting of se^uns which sometimes occurs. If the

./

/ '^^^D

Vifi. 213.

20fl


paint is api)licd to the rosin, the hitter, with time, will crack, and the

rain will soak under the cracked rosin to the tin surface. Even when

the surface of the roof is dry, by raising the cracked rosin, moisture

will often be found inulerneath, which naturally tends to rust the plate

more and more with each storm. If the rosin is removed, the entire

tin surface is proteeted by paint.

One of the most difficult jobs in flat-seams roofing is that of cover-

ing a conical tower. As the roof in question is round in plan and taper-

ing in elevation, it is necessary to know the

method of cutting the various patterns for the

sheets. In Fig. 214 ABC shows the eleva-

tion of a tower to be covered with flat seam

roofing, using 10 X 14-inch tin at the base. As-

suming that the tower through B C is 10 feet 6

inches, or 120 inches, in diameter, the circum-

ference is obtained by multiplying 120 by3.141G which equals 395.8410, or say 390

inches. As 10 x 14-inch plate is to be used at

the base of the tower the nearest width which

can be employed, and which will divide the

space into equal spaces, is 13^ inches without

edges, thus dividing the circumference in 30

equal spaces. This width of 13^ inches to-

gether with the length of the rafter A B or B Cin elevation, will be the basis from which all the

patterns for the various courses will be laid off.

At any convenient place in the shop or at

the building, stretch a piece of tar felting of

the required length, tacking it at the four corners with nails to

keep tlie paper from moving. Upon the center of the felting strike

a chalk line as A B in Fig. 215, making it equal to the length

of the rafter A B or A C in Fig. 214. At right angles to A B in

Fig. 215 at either side, draw the lines B D and B C each equal to Of

inches, being one half of the 13|^ above referred to. From the points

C and D draw lines to the apex A (shown broken). As the widtli of

the sheet used is 10 inches and as we assume an edge of f inch for

each side, thus leaving 9j inches, measure on the vertical line A B

lengths of 9| inches in succession, until the apex A is reached, leaving

Fig. 214.

204

siiKirr MF;r\i. wohk

the liist slut't at tlii' top to ••miu- a.s it may. 'I'limu^li tlie|M>iiiLs tliiis

(ilttaiiinl oil A I? tiraw liiu-s|»arallfl

to (' 1) iiitrrstatin;; the hues A <"

ami A l) JUS shtiwii. 'I'heii the variiiis .^lla|M•smarketl I 2 .'{ etc. will

lie the net i)atterii.s for siniilarlv iminhered' A

courses. 'I'ake the shears and cut out the

jtatterns on the felting and nuuiher them a.s

re(|uiretl.

For example, take the j)aj)er pattern

No. 1, place it on a sheet of tin a.s shown in

I'ig. 21t), and allow g-ineh edges all arounil,

and notch the corners .\ B (' and D. Mark

on tlie tin pattern "No. 1, 21> more", as 'AO

sheets are re(julre«l to go arouixl the tower,

and cut 29 more for course No. 1. Treat

all of the paper patterns from No. 1 to tiie

apex in similar maimer. Of course where

the patterns become smaller in size at the

top, the waste from other patterns can he

used.

In Fig. 217 is .shown how the sheets

should he edged, always being careful to

have the narrow siile towards the top with

the edge toward the outside, the same as in

flat seam roofing. Lay the sheets in tlie

u.sual manner, breaking joints as in general

|)ractice. As the seams are not sohlered

care must be taken to lock the edges well.

.\fter the entire roof is laid and before closing the seams with the nudlet

take u snuill brush an<l

paint tin' locks with thi«-k

\vliit«' lead, then close

with the mallet. This

C - > will make a water-tight

job. .\fter the r(M)f is


terns the line from C to D and all following lines should be curved,

as if struck with a radius from the center A, and not straight as shown.

To those the wi-iter would say that the curve would be so little on a

small pattern, where the radius is so long, that a straight line answers

the purpose just as well in all practical work; for it would amount to

considerable labor to turn edges on the curved cut of the sheet, and

there is certainly no necessity for it.

WTien different metals are to be connected together, as for instance

tin roofing to copper flashing, or copper tubes to galvanized iron gut-

ters, or zinc flashings in connection with copper linings, care must be

taken to have the copper sheets thoroughly tinned on both sides where it

joins to the galvanized iron, zinc, or other metal, to avoid any electroly-

sis between the two metals. It is a fact not well known to roofers

that if we take a glass jar and fill it with water and place it in separate-

ly, two clean strips, one of zinc and the other of copper, and connect the

two with a thin copper wire, an electrical action is the result, and if the

connection remains for a long time

(as the action is very faint) the zinc

would be destroyed, because, it mayhe said, the zinc furnishes the fuel

for the electrical action, the same

as wood furnishes the fuel for the

fire. Therefore, if the copper was

not tinned, before locking into the

other metal, and the joint became

wet with rain, the coating of the

metal would be destroyed by the

electrical action between the two metals, and the iron would rust

through.

Wliile the roofer is seldom called upon to lay out patterns for any

roofing work occasion may arise that a roof flashing is required around

a pipe passing through a roof of any pitch, as shown in Fig. 218, in

which A represents a smoke or vent pipe passing through the roof B B,

the metal roof flashing being indicated by C C. If the roof B B were

level the opening to be cut into the flashing C C would simply be a

true circle the same diameter as the pipe A. But where the roof

pitches the opening in the flashing becomes an ellipse, whose minor

axis is the same as the diameter of the pipe, and whose major axis is

ao6

^'TTFF'I' MKTAL WoUK 1~7

ttjiiallo till' pitch a h. In I'ig. L'l'J i.s slmwii liow Uiis i>|>c>nin^ is ()l>-

taii)e«l by tlie use of ji few nails, a strinir. ami a pencil, which the rfM)fer

will always have handy.

First tlraw the line A W representing the >lant of the roof, and

then make the pipe of the <lesireil size passing through this line at its

[iroper angle to the roof

line. Xe.xt draw the center

line H ."^ of the pipe, as

.shown. ' all t h e po i n t

where this line intersects

tlie r«>of line, I, and the

points where 1) F. and <" F

intersect A B. (J and II r«'-

spectively. Through I draw

K L at right angles tn .\ H.

making K I and 1 L each

cipial to the half diameter

of thej)ipc. Having estal>-

lished the minor axis K L

and the major axis O II.

the ellipse is made by tak-

ing 1 II, III- half the major

axis, as a radius, and with

L as a center strike arcs in-' '*^- -'•'

tersecting the major axis, at iM)ints M ami N. Drive a small nail in

each of these two jM)ints and attach a .string to the nails as shown by

the dotted lines K M X. in sui-h a way that when a j)encil |K)int i>

placnl ill the string it will reach K. Move the |)cncil aK)ng the

string, keeping it taut all the tinu' imtil the ellipse K II L (i is ol>-

tained. Nt>te how the position of the string changes when it reache."

a, th«'n h, etc.

SI \\IHN(i-Sr:AM kOOl l\(i

Another form of mclal rooliiig is that known as standing seiun.

which is u.s«'<l on steep nnifs not less than \ pitch, or \ the withh

of the building. It consists of metal sheets whose cni.-vs tir hori/jontal

s<'am.s are |o<'k«'d a> in (hit M-am nwiling, and who.se vertical s«>ams are

.standing Icx-keil seams, as will be dcscrilxtl in conne«-tion with Figs.

•zoi


Fig. 220.

220 to 229 inclusive. Assume that 14 x 20-inch sheets are used and

the sheets are edged on the 20-inch sides only, as shown by A in Fig.

220, making the sheet 13 x 20 inches. After the required number of

sheets have been edged, and assuming that the length of the pitchedroof is 30 feet, then as many sheets are

locked together as will be required, and

the seams are closed with the mallet

and soldered. In practice these strips

are prepared of the required length in the

shop, painted on the underside, and when

dry are rolled up and sent to the building.

If desired they can be laid out at the build-

ing, which avoids the buckling caused by rolling and transportationfrom the shop to the job.

After the necessary strips have been prepared they are bent upwith the roofing tongs, or, what is better and quicker, the roofing edgerfor standing-seam roofing. Tliis is a machine into which the strips of

tin are fed, being dis-

charged in the requiredbent form shown at A or

B in Fig. 221, bent up 1

inch on one side and IJ

inches on the other side.

Or the machine will, if^'^- ^'^^^

desired, bend up \\ inches and \\ inches, giving a |-inch finished

doubled seam in the first case and a 1-inch seam in the second.

WHien laying standing-seam roofing, in no case should any nails

be driven into the sheets. This applies to tin, copper or galva-

nized iron sheets. A cleat should be used, as shown

in Fig. 222, which also shows the full size for laying

the sheets given in Fig. 221. Thus it will be seen in

Fig. 222 that \ inch has been added over the measure-

ments in Fig. 221, thus allowing edges.

These cleats shown in Fig. 222 are made from

scrap metal; they allow for the expansion and con-

traction of the roofing and are used in practice as shown in Fig. 223,

which represents the first operation in laying a standing-seam roof,

and in which A represents the gutter with a lock attached at B. The

I"

J-k

^XCLEATN

Fig. 222.

208

SIIKET MKTAL WORK 170

j;imii Ihim;^' la.^itncti in |)Ositinn hv means of cleats unrler the

lock li—the same as in flat .scam nxdiiig—the stamiiri;; y^aiu

.stri|»s

arc laiti its follows: Take the strip (' ami lock it well into the

lock H «)f the "gutter A its shown, ami place the cleat sliown in Fig.

222 tijijhtly a},'ainst the upright lientl of the strip C in Fig. 2'2.'i a^ shown

at 1), anti fasten it to the roof by means of a 1-inch roofing nail a.

Fig. 223.

Press the strip C firmly onto the roof and turn over e<lge b of the cleat

I). This holds the .sheet C in position. Xow take the next sheet H,

|)rcss it down and against the cleat 1) and turn over the e<lge d, which

holds K in jKJsition. The.se cleats should be j)laced about IS inches

Fig. -JJ-I. Fig. 225.

aj)art and by using them it will be sitMi that no nails have Ikhmi driven

through the .sheets, the entire roof being held in positi«)n by nieans cf

the cleats onlv.

The .second operation is .shown in Fig. 22 I. By means of the

hantl ilouble si-amer and mallet (>r w itii the roofing double .seamers and

.s<juee/.ing tongs, the single .seam is made as shown at «. The third

and last operation is .shown in Fig. 22') where by the n.se «)f tlte .same

tools the doubled seam a is obtained. In Fig. '2'2^) is .shown how the

finish is made with a ctimb ridge at tin*(oj).

The .sheets A A A have


on the one side the single edge as shown, while the opposite side B has

a double edge turned over as shown at a. Then, standing seams hhhare soldered down to e.

In Fig. 227 is shown how the side of a wall is flashed and counter

Fig. 226.

flashed. A shows the gutter, B the leader or rain water conductor,

and C the lock on the gutter A, fastened to the roof boards by cleats

Fig. 227.

9-s shown at D. TJie back of the gutter is flashed up against the wall

as high as shown b^ the dotted line E. F represents a standing-seam

strip locked into the gutter at H and flashed up against the wall as high

310

SHEET METAL WORK ISl

xs shown by tlic ilotteil line J J. .Vs the Ha-sliing J J E Ls not fastenetJ

at any part to the wall the l>eain.s or wall can settle witliout tlLsturhing

the tliushing. The counter or cap Hashing K K K is now slep{>e<J as

Jiown by tiie heavy lines, the joints of the brick work iK'ing cut out to

allow a one-inch flange d d d etc. to enter. This is well fastenetl with

flashing hooks, as indicatetl by the small dots, and then made water-

tight w ith roofer's cement. As will be seen the cajj flashing overlaps the

base flashing a tlistance indicated by J .1 and

covers to L L; the corner is double seamed at

a b. M shows a sectional view through the

gutter showing liow the tubes ami leatlers are

joined. The tube X is flanged out as shown

at i i, and soldered to the gutter; the leader

() is then slijjped over the tube N as shown,

and fastened.

In the section on Flat-.^cam Roofing it

was explained how a conical tower, Fig. 211,

would be covered. It will be shown now

how this tower would be covered with stand-

ing-seam roofing. As the circumference of

tlie tower at the base is 396 inches, and

assuming that 1-1 x 20-inch tin ))late is to

be use«l at the base of tlie tower, tlie nearest

width which can be employetl and which

will divide the base intoe<^{ual spaces is 17^''^

inches, witliout edges, thus divitling the cir-

cumference into 23 equal parts. Then the

width of ITn'j inches and the length of the

rafter A H or A C in elevation will be the^

basis from which to construct the pattern

for the standing .seam strip, for which pro-

cee«l JLs follows:

T,ct .\ H (

'

1) ill Fig. 22.S represent a 2()-inch wide strip l.icktNl and

soldj-retl to the n-cpiirnl length. Through the center of ilie strij) draw

the line 1'. F. Now measure the length of the rafter .\ \\ or .V (' in Fig.

211 and place it on the line V. V in Fig. 22S its .shown from II to F. At

right angles to 11 F on eitluT side draw F O and F \. making each

e<|ual to S\\ in»'hc.s, being one half of the ITj'j alH)ve ref»Trc«l to.

21 1

182 SHEE'l METAL \WRK

From points L and O draw lines to the apex H (shown broken). At

right angles to H L and H O draw lines H P equal to 1^ inches and

H S equal to 1 j inches respectively. In similar manner draw L D and

O C and connect by lines the points P D and S C. Then will P S C Dbe the pattern for the standing seam strip, of which 22 more will be

required. When the strips are all cut out, use the roofing tongs and

bend up the sides, after which they are laid on

the tower, fastened with cleats, and double

seamed with the hand seamer and mallet in

the usual manner.

If the tower was done m copper or galva-

nized sheet iron or steel, where 8-foot sheets

could be used, as many sheets would be cross-

locked together as required; then metal could

be saved, and waste avoided, by cutting the

sheets as shown in Fig. 229 in which A B C Dshows the sheets of metal locked together^ and

E and F tlie pattern sheets, the only waste be-

ing that shown by the shaded portion. Where

the finial D in Fig. 214 sets over the tower, the

standing seams are turned over flat as much'^' ""

as is required to receive the finial, or small

notches would be cut into the base of the finial, to allow it to slip over

the standing seams. Before closing the seams, they are painted with

white lead with a tool brush, then clos.ed up tight, which makes a good

tight job.

CORRUGATED IRON ROOFING AND SIDING

Corrugated iron is used for roofs and sides of buildings. It is

usually laid directly upon the purlins in roofs constructed as shown in

Figs. 230 and 231, the former being constructed to receive sidings of

corrugated iron, while in the latter figure the side walls of the building

are brick. Special care must be taken that the projecting edges of the

corrugated iron at the eaves and gable ends of the roof are well secured,

otherwise the wind will loosen the sheets and fold them up. The cor-

rugations are made of various sizes such as 5-inch, 25-inch, IJ-inch

and |-inch, the measurements always being from A to B in Fig. 232,

and the depth being shown by C. The smaller corrugations give a

313

SUKKT MKIAI. WoUK IS3

luuri' pleasing ;i|)|K'aran(i*,Imt llie lurjier rurriij(ation.s are sillier and

will span a ^eacer tli.staiict'.thfreljy juTjiiittiiij,'the jmrliiis to |je further

apart.

J

I'ig. 230.

The tliickne.-vs of the metal f;ene'-ally iise<l for roofni}; aiui siding

varies from No. 24 to No. Ki gauge. Hy actual trial made by The

/

i-r

184 SHEET IMETAL WORK

TABLES

The following tables will prove of value when desiring any infor-

mation to which they appertain.

MEASUREMENTS OF CORRUGATED SHEETSDimensions of Sheets and Corrugations.

RESULTS OF TEST

of a corrugated sheet No. 20, 2 feet wide, 6 feet long between supports, loaded

uniformly with fare clay.

Load

;tif.i-:t mi"'''\' wmrk w*

The follitwiiij!; talilf is tul<ulate«l for sUwts .{(1^ iinlifs wi«Je lK-fi>re

ct)rruj;aliiig.

j:?

23StW

"1.1

I M.'.

.018 .73


Should the gable have a fire wall, then let the sheets A butt against

the wall and flash with corrugated flashing as shown in Fig. 235, over

which the regular cap or counter flashing is placed as explained in

connection with Fi";. 227. Should_

B ^^^—.^^ \^__ the ridge of the roof A butt

against a wall, as shown at B in\^/y/yyyjmi^m\\\w///m'Mm^ROOF LINE

Fig. 230, then an end-wall flash-

ing is used as is shown in Fig.

236 which must also be capped,

by either using cap flashing or

allowing the corrugated siding

to overlap this end-wall flashing

Fig. 234. Fig. 235.

as would be the case at B in Fig. 230. Now commence the

second course at the eaves, giving one and one half corrugations for

side lap, being careful that the side corrugations center each other

exactly and nail with washers as shown in Fig. 237. Nail at every

other corrugation at end laps,

and at about every 6 inches at

side laps, nailing through top

of corrugation as shown in

Fig. 237. Continue laying inFig. 236.

this manner until the roof is covered.

The same rule is to be observed in regard to laps and flashing if

the corrugated iron were to be fastened to iron purlins, and the method

of fastening to the iron frames would be accomplished as shown in Figs.

238 to 240 inclusive. Assuming that

steel structures are to be covered, as

shown in Figs. 230 and 231, then let

A in Fig. 238 be the iron rafter, Bthe cross angles on which the sheets D are laid, then by means

of the clip or clamp C, which is made from hoop iron and bent around

tlie angle B, the sheets are riveted in position. In Fig. 239 is shown

another form of clamp, which is bent over the bottom of the angle iron.

Fig. 237.

216

;HKF.T MK'IAI. WOHK \S1

Fig. 240 slu)\vs still iiiiotliiT iiietli<Ml, wlierc theclaiiii)

F is riveted to the

blieet B at K, tlieii tiiniitl unminl the angle A at D. '!'»• uvriiil having

the storm drive in between tlie corrugated opening at the caves, cor-

rugatetl wood filler is used a^ shown in Fig. '2\\. 'I'his keeps out the

^

V I

Fir. 210.

Fig. 2:W. FiR. 239.

snow and sleet. On imn framing this is made of pressed metal.

Another form of corrugated iron roofing is shown in Fig. 242. This is

put down with cleats in a manner similar to standing-seam r(X)fing.

If tliere are hips on the roof, the corrugated iron should l)e care-

fully cut and the hip c«)vered

with sheet lead. This is hest

done by having a wooden cove

or filler place <1 on the hip,

again.st which tlie roofing butts.

Sheet lead is tlien formed over

this wooden core and into the

corrugations, and ta.stcne<l by

meJMis of wood screws through the lead cap intt» the W(Kiden core.

'i'he lead being soft, it can be worked into any desire<l shape.

When a valley occurs in a hippctl roof, form from plain shivt iron

a valley as .shown in Fii:- 21."?, being sure to give it twoa>atsof paint

before laying, and make

it from 24-intii widesheets, lientling u

jt1 2

i n ch <-s on each .si«le.

'*' "Fit it in the valley, an«l

cut tlu- corrugated iron to lit the re(|uired angh-. Then lap tlie

corrugated iroti over the vallev from (I to s in(•lle^.

When a chinmey is to Im- flashnl, a.s shown in Fig. 244, use plain

iron, ix-nding U|)and flashing into the chimney joint>, and allowing

217


the flashing to turn up under the corrugated iron at the top about 12

inches and over the corrugated iron at the bottom about the same

distance. At the side the flashing should have the shape of the cor-

rugated iron and receive a lap of about 8 inches, the entire flashing

Fig. 242.

being well bedded in roofer's cement. \Vlien a water-tight joint is

required around a smoke stack, as shown in Fig. 245, the corrugatediron is first cut out as shown, then a flashing built around one half the

upper part of the stack to keep the water from entering inside. This

is best done by using heavysheet lead and riveting it to

the sheets, using strips of sim-

i 1 a r corrugated iron as a

washer to avoid damaging the

lead. Before riveting, the

flashing must be well bedded

in roofer's cement and then

make a beveled angle of

cement to make a good joint.

After this upright flashing is

in position a collar is set over

the same and fastened to the

stack by means of an iron ring

bolted and made tight as shown. Cement is used to make a water-

tight joint arovmd the stack. This construction gives room for the

stack to sway and allows the lieat to escape.

Sometimes the end-wall flashing shown in Fig. 236 can be used

Fig. 243.

218

FRONT AND REAR VIEWS OF RESIDENCE OF MRS. H. M. COBB, MAGNOLIA DRIVE,CLEVELAND, OHIO

Watterson & Schneider, Architects, Cleveland, Ohio.

FRONT AM) KKAK \11.WS OK HKMKKNU. ^l^ MH. M. 1. llHlMls, .MAi.Sviii\ i.mi.i,

I I.KVKI.ANI). OHIO

Wnitprooti A Srhnrlilpr. An-hliwin, t'lcvplaiiil. t>l>li«.

Cr," i>- • »3Rnno. Flmt Siorjr WulU of MrCatmlnnil nrlok. %\cnW o' AVir..n. QUo. Koofl vf('oliibltinlloii KnlTllr

SHEET MEIWL WoKK 1S^»

to goo«l a<lvaiita<jc in Imiltliiiji; tlie ui>riglit llasliing in Fi;^. 24'j. Where

the currugatetl iron inet't.-> at the ridge, as at 1) and i) in Figs. 2'.U) and

^p-p_^-_

Fig. 244.

^\, a wooden core is plac^I in position a.s exphiined in connection witli

tlie hij) ridge, and an angle ridge, pressed by dealers who furnish the

TiK. 21.".

corriigatnl iron, is phiced over the riilge jis .sh(»wn in Fig. '2\i\. Whena ridge roll i.s re«jwiri-d, the .shape .shown in Fig. '217 is eniployitl.

210


These ridges are fastened direct to the roof sheets by means of riveting

or bolting.

LAYING CORRUGATED SI DING

Before pntting on any corrugated siding or cla])boarding, as

shown in Fig. 24S, a finish is usually made at the eaves by means of a

Fig. 24G.

hanging gutter or a plain cornice, shown in Fig. 249, which is fastened

to the projecting wooden or iron rafters. This method is generally

used on elevators, mills, factories, barns, etc., where corrugated iron,

crimped iron or clapboards are used for either roofing or siding. This

Fig. 217.

style of cornice covers the eaves and gable projections, so as to make

the building entirely ironclad. When laying the siding commence

at the left hand corner, laying the courses from ba.se to cornice, giving

the sheets a lap of two inches as the ends and one and one half corruga-

Fig. 248.

tions at the sides. Nail side laps every 6 inches and end laps at every

other corrugation, driving the nails as shower in Fig. 250.

Where the sheets must be fastened to iron framing use the same

method as explained in connection with Figs. 238, 239 and 240. In

this case, instead of nailing the sheets, they would be riveted. If siding

is put on the wooden studiling care should be taken to space the stud-

ding the same distance apart as the laying width of the iron used. In

220

siii:i:r miim. \\<)1:k' i'.»i

tliis vase piet-es of stiidiliti;; sIhmiM In- plat «i| Ix'twdMi the iipri^liLs at

tlie eml of facli .slu-rt (u nail tlir laps. \\ lini toveriiig gruiii cievutur"*

Fig. 2.")«.

it is necessary to use swinging scall'olds. (\)nuneinr at the hase and

carry up the course to the eave, the leii<,'tli of the scatt'ol.!. ( 'omineiKe

at tlie left luiiid and j^ive the sheets a lap of one coriui^ation on the side

and a two-inch lap at the end.

Nail or rivet in every corru-

gation 'i inches from the lower

end of tlio sheet; this allows

for settling of the huilding.

When any structure is to

lie (ii\frfd oil two (ir nior«'

.sides, corner casinjjs made of

flat iron are eniploved, of a

sha|<e similar to that .shown iit

H, I'V- -d. I( will he s.eii

that a ralihet i^ heiit on lH>th

.sides (I an<l h to admit the

A

-diy

KiK -'.'' I.

.siding. This makes a neat finish on tlu* outside and hides the

rough edges of tlie .siding. If a window opening is to have

casings a jamli is usnl as shown at .\, l-'ig. 'J.'»l ,whirh has a similar ral>-

l.el at II to re«'eive the siding, and a sipiare heiid at l> t«» nail against the

frame. In I'ig. J.'iL* is .shown the <ap of a window or o|K>ning. It is

091


bent so that a is nailed to the window or other frame at the bottom,

while b forms a flashing over which the siding will set. Fig. 253 shows

the sill of a window, which has a rabbet at a, in which the siding is

Fig. 252. Fig. 253.

slipped ;then b forms a drip, and any water coming over the sill passes

over the siding without danger of leaks; c is nailed in white lead to the

window frame.

Another use to which corrugated iron is put is to cover sheds and

awnings. Sheets laid on wood are nailed in the usual manner, while

sheets laid on angle iron construction are fastened as explained in the

Fig. 254.

preceding sections. In Fig. 254 is shown an awning over a store laid

on angle iron supports. In work of this kind, to make a neat appear-

ance, the sheets are cui'ved to conform to the iron bracket A.

222

CORNICE OVER BRICK BAY *

An elevation and plan of a brick. lj;iy are .shown in the illu.stration, tho

îdes of which are S inches, 3 feet 2 inches and Ft feet 10 inches wide. Iîjm

or flanges for soldering are to \)e allowed on the 3 feet 2 inch pieces and no laps

on the S inch and 5 feet 10 inch i)ieces. The lookouts or iron braces are indi-

cated in the plan by the hea^•y dashes making a total of 9 required.

After the detail ."section is drawn and knowing the angle of the bay in plan,

the angle is placed as shown by ABC, being careful to place CB on a line drawn

vertically from .'i—1 in the .•section. The miter line Ls then drawn as shown by

BI), the section divided into equal spaces, and vertical lines dropped to the

miter line BD as shown. At right angles to BC the girth of the section Ls

drawn as shown by similar figures from 1 to 2G, through which points at right

angles to 1-2G, lines are dra\\'n and intersected by similar numbered lines

drawn from the miter line BD at right angles to BC, thus obtaining the upjwr

miter cut shown. Now using this miter cut in practice, make the distance

from either points 25 or 24 (which rcpre.sents the line of the wall) equal to

8 inches, 3 feet 2 inches and 5 feet 10 inches. The 3 feet 2 inches and 5 feet

10 inches have oppoîte miter cut^ as shown.

As will be seen by the plan, two eight inch j)ifces will be required, one

right and one left and two 3 feet 2 inch and one 5 feet 10 inch pieces. Nine

iron lookouts will be required formed to the shape shown in the detail section*

where holes are punched for bolting as there indicated.

*1 nv illuatrutlon rcfemxl to will l>o (ouud oa tlie buck of tliiii imgv.

823

\\\\\\\v.y\\\\\\\\\v

wa,-r*

Co

-^ o<t^ W "

^ ." -t^ >K

©-^

^ _3

-

O «

in

(0

cu

toow<nHH(fl

sHno«a-

aHtoO2OHi*

J6<

Heeo

7.,-2-.e-

:,oi-s^-

SHEET METAL WOPKI'AHT II

COIi^MCi: WORKThere is u») trade iti the liuildiii^ line ti)-<lay wiiieh Iia^ ina«le .-.uch

rapid projjress as that of Sheet-Metal (Joniice, or Arehitectural Sheet-

Metal Work. It is iKit very lun^ since the j^eiieral scope of this braneh

iif (Taftsinaiishij) merely represented a tin-shop hnsiness on a larj^e

seale. But as things are tt)-tlay, this is changt^l. Fn)iu an enlarged

tin-shop business, sheet-metal cornice work, including under that title

everA' branch of architectural sheet-metal work, has l)ecoit'e one of tlie

substantial industiies of the countrA-, comparing favorably with almost

anv <»ther mechanical branch in the building tra«les. Nor is this wrkconfined lo the larger cities. In tlie smaller towns is .>.hown the prog-

ress of architectural sheet-metal work in the erection of entire building

fronts consMurtcd from sheet metal.

CONSTRlCriON

Sheet-metal cornices have heretofore, in a great measure, l>een

duplications of the designs commonly em|)loyed in wood, which, in

turn, with minor modifications, were imitations {»f stone.

With the marked advancement of this industry, however, this

need no longer be the ca.se. A .sheet-metal corni«'e is not now imita-

tive. It j)os.sessesa variety and beauty peculiarly its own. .\'o

j»at-

lern is to«) complex or too diilicult. I )esigns are salisfact«»rily e.\tH-ut«il

in sheet metal which are imjM>.ssibleto product' in any other material.

liy the free and judi«'ious aj)plication of j)res>ed metal ornaments, a

pn»<luct is obtained that eijuals carved work. For bo|dnes.s of figure,

sharj) and clean-<ut lines, sheet-metal work takes the leail of all coim-

|»ctitors.

In onler that there nuiy be no misimdersianding as to the various

onlained in what the sheet-metal workir ealls a "cornice."

I '„ . >.» ha.i been prepared, which giv«'s the nanus of all the meiMbers

in tlu- "entablature"—the architeitural name for what in Uu* .sliop ia

2aA

known as the cornice. The term "entablature" is seldom heard

among mechanics, a veiy general use of the word "cornice" having

supplanted it in the common language of business.

An entablature consists of three principal parts—the cornice, the

frieze,and the architrave. A glance at the illustration will serve to

show the relation that each bears to the others. Among mechanics

the shop term for architrave is foot-moulding; for frieze, panel; and for

cr

1UJ

i—-

u£

i QUARTER ROUND

STILE

COVE

PANEL

V PANEL MOULD \

i—u

Xoa.<

.JL.

WA5H

/dentil mould q,0

J '"ILLETy QUARTER ROuFTd^

DRIP

FASCIA

FASCIA

I

_lUJ

Z

I

OQO -I

o

Fig. 255.

the subdivisions of the cornice, dentil course, modillion coixm^, bed-

mould, and croum-mould. In the modillion course, are the modiUion-

band and mod illion-mould; while in the dentil course are ihe dentil-

hand and dentil-mould. Drips are shown at the bottom of die crown-

and foot-mould fascias, and the ceiling under the crown mould is called

the planceer. The edge at the top of the cornice is called a lock, and is

used to lock the metal roofing into, when covering the top of the cor-

226

SHEET >frrAE WORK 195

nicv. In the panel, tliere are tlie panel pruper, the paael-iiwuld, aii<l

the Mile. The side and fmnt of the inodilhon are als4) shown.

Fij;. 2')<> shows the side and fr«int view of what <s known as a

hracket. Lar^e tenninal brackets in

cornices, which ])roject l)eyond the

niouldin^'s, and a;;ainst which the

nionhUngs end, are caUed trnsses, a

front and a side view of whidi are

shown ill Fi^. '2'u . A hlock phiced

above a common bracket a<;ainst

which tlie monlding ends, is calle<l a

stop hlfx'k, a fnmt and a side view of

which are shown in Fig. 25S.

Fig. 250.

FRONT

F'i<^.2.jU is tlie front eleva-

tion of a cornice, in which are

iiiiiiiiiii i iii i iii i iiiiiiii i iu iiiii sliown the truss, the bracket, the

modillion, the dentil, and the

panel. It is stnnetinies the case,

in the construction of a cornice,

that a bracket or modillion is

called for, whose front and sides

are car\e«l as .shown in the fmnt

an«l side views in F^ig. 2(50. In

that case, the brackets are ol)-

tained fmnx dealers in pressetl

ornaments, who make a specialty

of this kin«l of work. 'I'he same

aj)[)licsto capitals which would

be reipiircd forjblasters or col-

SIDE

Imk. '-ViT.

unins, such a.s tho.se shown in Figs. 2G1 and 2l'i2. The pilaster or

oolinnn would be formed » r

up in .sheet metal, and the !

ca|>ital purcha.se«l antl sol-

dered in position. In liu

2r)3, A .shows an inclined

moulding, which, a.s far as front

general position is con-

cenied, would be the same as a gable monlding.

SIOC

Fi«. 2.VS.

2'27


Raking inouldings are those which are incHned as in a gable or

pediment; but, inasmuch as to miter an inchned moulding (as A) into a

horizontal moulding (as B and C), under certain conditions, necessi-

tates a change of profile, the term "to rake," among sheet-metal work-

ers, has come to mean "to change profiles" for the accomplishment of

FRONT ELEVATIONFig. 259

such a miter. Hence the term "raked moulding" means one whose

profile has been changed to admit of mitering.

The tenn miter, in common usage, designates a joint in a mould-

ing at any angle.

Drawings foiTn a veiy important part in sheet-metal architectural

FRONT ELEVATION SIDE ELEVATIONFig. 2G0.

work. An elevation is a geometrical projection of a building or other

object, on a plane perpendicular to the horizon—as, for example,

Figs. 259 and 263. Elevations are ordinarily drawn to a scale of | or

228

>liHKT MHTAI. WORK 19/

\ iiuli ti> till' fiMit. A .^fctionul drawituj sliuws a view <<f a Ijuilditig Ot

(itluT <»l)ject as it would a|)|)earif cut in two at u jjivcii vertical line—

a.s, for example, Fij;. 2').*). Detail draw'mtfs arronliiiarily full size, ai.d

A--SEC i iUN

ON<//'^.-r-. .V/. / ....

Fiu. -'t,!. Fit; 2(V.>.

are often called work'nuj drawhuja. Traeinrjs are (iii|iiicate <lrawings,

made \>y traciii<r iipon traiisparct't i-lotli or paper j)Iace(lover tlie orig-

Fi»?. 2rt3.

inal drawiiij;. M-inv other terms might l>e ititrodiiccti her«'; l>nt

eiioiigli, we lielieve, ha '•' l>«'eii presented to give the student the leading

general ]Miint.s.

22(i

198 SHEET METAL ^NORK

A few words are necessary on the subject of fastening the cornice

to the wall.

Sheet-metal cornices are made of such a wide range of sizes, and

are required to be placed in so many different locations, that the

methods of construction, when wooden lookouts are employed and

Fig. 264.

when the cornice is put together at the building in parts, are worthy of

the most careful study. The general order of procedure in putting

up, is as follows:

The foot-moulding or architrave a b (Fig. 264) is set upon the

wall finished up to/,

the drip a being drawn tight against the wall.

The brickwork is then carried up, and the lookout A placed in position,

the wall being carried up a few courses higher to hold the lookout in

position. A board B is then nailed on top of the lookouts (whichshould be placed about three feet apart) ;

and on this the flange of the

foot-mould b is fastened. The frieze or panel 6 c is now placed into

the lock B, which is closed and soldered; when the lookout C and the

board D are placed in their proper positions^ as before described.

230

siiKi<n^ .\ii-rrAi. work M9

The plaiifeer ami l»o<l-ini>ul(l c d an- iiow lucke«l and .s<»l(lere<l at

1>, and the Io<jk(iUt E phiceil in position, with a lx)ard F phicetl under

t!>e liHikoiits the entire lenj^th of the cornice; onto this l>oard the j>lun-

ceer is fastened. Having the |)n)j)er measurements, the framer now

constructs his lookouts or hrackets (I II I H, fastening tt) the beam at

T, when the crown-mould d c is fastened to the plani-eer, through the

flange of the drip at d, and at the top at r. The joints l)etween lengtns

of mouldings, are made by lapping, riveting, or bolting, care l>eing

taken that they are joined so neatly its

to liide all indications of a seam when

finished and viewed from a sliort

distance.

If brackets or modillions are to

be placed in position, they are riveted

or bolte<l in i)osition; or sometimes the I "T "'"^''°*»'j

l)ack of tiie cornice is blocked out

with wood, and the brackets screweil

in position tlirough their flanges.

\Miile a galvanizeil-iron cornice

thus constructed on wooden lookouts

will resist fire for a long time, a strict-

ly fireproof cornice is obtained only

by the use of metal for supports and

fastenings, to the entire exclusion of

w(H)d. This flrej)roof method of con-

Ntniction is shown in Fig. 20.'). In-

stead of piitting up ill j)arts on the l)uilding, the c-ornice is i-on-

stnicted in one piece in the shoj) or upon the ground, an<l lioisteil

to the top of the wall in long lengths easily handled. A <lrip a is used

at the bottom of the foot-mould, and the joints nuidc in the way in-

di(ate<l at h and r, with a lock at d. Hand iron supp«»rts and braces

are \iscd, formc(l to the general ctiutour of the parts as shown bv .\ \\

( ', an<l bolted direct to the cornice, as shown, before hoisting.

When the cornice .sets on the wall jus at (', anchors are fastenni

to the main brace, as at I> and I., with an cud l>«'ut up or d«»wn for

fastening. If tlie c<»rnice sets perfectly phnnb. the nut.son carries uphi> wall, which holds the c«»rni<c in a lirni iM>^itii>ii. The top and

hark iirr then framrd in flu- iisn.-il nwiimer and ct)vere<l bv the metal

Fig. 20.';.

881

roofer. In constnirtiiif^ cornices in this manner, the nionldiniis are

run througli solid, behind jill l)rackets and niodillions. The brackets

and niodilhons are attached by means of riveting through outside

flanges.

SHOP TOOLS

One of the most important tools in cornice or architectural sheet-

metal working shop is the brake. On those operated by hand, sheets

are bent up to 8 feet in one continuous length. In the laCrger shops,

power presses or brakes are used, in which sheets are formed up to 10

feet in length, the press being so constructed that they will form ogees,

squares, or acute l)en(ls in one operation.

Large <S- f)r 10-feet squaring shears also form an important ad-

dition to the shop, and are operated by foot or power.

\Mien cornices are constructed where the planceer or frieze is verv

wide, it is usual to put crimped metal in, to avoid the waves and buck-

les showing in the flat surface; for this purpose the crimpitig machine

is used.

In preparing the iron braces for use in the construction of fire-

proof cornices, a punchltu/ machine and slittimj shears are used for

cutting the band iron and punching holes in it to admit the bolts.

\Miile braces are sometimes bent in a vise, a small machine known as a

hra^e bender is of great value in the shop. In large fireproof building

constructions, it is necessary that all doors, window frames, and even

sashes be covered with metal, and made in so neat a manner that,

when painted and grained, no differences will be apparent to indicate

whether the material is wood or metal, the smallest l)ends down to \

inch being obtained. This, of course, cannot be done on the brakes

just mentioned, but is done by means of the draw-hcnch, which is con-

structed in lengths up to 20 feet and longer, operated by means of an

endless chain, and capal)le of drawing the sheet metal over any shaped

wood mould as tightly as if it were cast in one piece. The smaller

tools in the shop are similar to those described in the Instruction

Papers on Tinsmithing and Sheet Metal Work, Part I.

METHOD EMPLOYED FOR OBTAINING PATTERNS

The principles applied to cylinder developments as explained in

the Tinsmithing and Sheet Metal Work courses, under the heading

of "Parallel-Line Developments," are also applicable for obtaining

232

SHEET Mtrru. WoKK 2xi\

90°

llif jialicni.^ fur :iiiv iiiiMil«liii<: wlu-ii- :(ll iiu-iiiIhts run para I lei; for it

makes int Wiirereiiee whatj)rulile

is eiiiiiloxed, Mt Imig a.s the lines nin

|»aralUIto one another, the i>arallel-line method is use«l. While

this method is ehiefly employed in corniee work, other proMems will

uris«'. ill which l!ie "Kadial-I.iiu" and rriaiij^'iilation" methoijs (ex-

plained in previous Papers) will lu- of >erviie.

'I'lie term ;,'enerally used in the >hop for pattern iiitiin}; on e<.rnief

work is inilir i-iitfiinf. To illiistrite, >iippo -c two piece-r of moiildin;;-^

are to l»e joined lo^'elher at

anjjie of IK)*^, as shown in Fi<;. V^-T"',

L'tit't. The first step necessarywoukl he to l)ise<t the j^iven

an^Ie an<l olitaiii the initrr-

linf and cut each piece so that

they wnidd miter to^'et her. If a

<arj)°iiter had t) make a joint of this kind, he would |)lace his moulding'in the miter-l)ox, and cut one

j>iece ri<,'ht and one pie<e left at an aiijjie

of l.")°, and he would l»e careful to hold the moulding in its proper po-sitifui l)eforo sawing; or else he may, instead of having a return miter

as shown, have a face miter as in

I

|»ictiire frame, shown in Fig.

L'(i7. 'I'he sheet-metal cornice-

maker cannot, after his mouldingis formed, place it in the miter-

l>o\ to cut the miter, hut must

lay it out—or, in other words,

develop it—on a Hat surface or

sheet of metal. lie nmst also he

kin. -'till.

\.»o.

XJLUFIr. :it>7.

careful to place the profile in its piopi-r |>o.sition with the miter-

liu'-'; or else, instead of ha\ing a return miter as shown in Fig. L!(i(>, lu*

will have a face miter as shown in Fig. 2<i7. If he lays out his w«trk

corre«tly, he can (hen cut two jiieces, fonn om- right and the other left,

when a miter will result hetween lln' two pieces of moulding and will

l<M,k as shown i*i Fig. LMWJ. If. |iowe\cr, a face miter is desinil. as

^howti in l''ig. 'ji\7, which is used when miters an- d«'sir«s| for panelsand other purjMises, the method of laying them out will lie esplaiiml as

we ppweed. The same principles reijuired for de\i'|oping I''igs. "Jllti

and Uti? are \isvt\, whether the mouldings are mitereil at angles oflH/'

2.T1


or otherwise. The method of raking the mouldings—

or, in other

words, changing their profile to admit the mitering of some other

moulding at various angles—will also be thoroughly explained as we

proceed.

VARIOUS SHAPES OF MOULDINGS

The style of mouldings arising in the cornice shop are chiefly

Roman, and are obtained by using the arcs of a circle. In some cases,

Greek mouldings are used, the outlines of which follow the curves

of conic sections; but the majority of shapes are arcs of circles. In

Fig. 268. Fig. 269.

Figs. 268 to 272 inclusive, the student is given a few simple lessons on

Roman mouldings, which should be carefully followed. As all pat-

tern-cutters are required to draw their full-size details in the shop from

small-scale drawings furnished by the architect, it follows that theymust understand how to draw the moulds with skill and ease; other-

Fig. 270. Fig. 271.

wise freehand curves are made, which lack proportion and beauty.

In Fig. 268, A shows the mould known as the cyma recta, known

in the shop as the ogee, which is drawn as follows :

Complete a square abed; draw the two diagonals a c and b d,

intersecting each other at e. Through e, draw a horizontal line inter-

secting adatf and 6 c at h. Then, with / and h as centers, draw re-

spectively the two quarter-circles a e and e c.

2.34

Cupples Hall, No. 2. Building is 207 FulI L.,u^, i. i >.. . v ., First Floor Devoted to MechanicalEngineering; Second Floor, to ij^lectrical Engineering.

The Library. The Building is 257 Feet Long. 46 Feet Wide." The Reading Room is 100 Feet by 41

Feet. The Stacks tor Books Have Room for Over 400,000 Volumes. Cost of Building, $250,000.

Busch Hall, the Chpmical Laboratory. Ih.- 1!iiu.Iiiil; i>.::;ni i',-.i L.,ug,60Feet Wide. CostJUO.OOO.

THREE FIREPROOF BUILDINGS OF THE UNIVERSITY OF WASHINGTON, ST. LOUIS, MO.Illustrating the Restful Effect of a Long, Almost Unbi-oUen Roof-Line.

SHEEl .\ifc:iAl. WORK 2(A

7

In Fiji. -•"»!K H shows tlu- rt/inu rtiTr.ia, known in the shop as the

(Hfir, rcversetl. ('oniplete u square a h r d, and «lniw tlie two lUimonuls

h d and a rinterseetinj; at «; thnai^h r, draw a vertical line intersecting

abut } and r d at //, which points are the respective centers fur tlie arcs

a f an<l e c.

C in Fig. 270 shows the cavetto, calle<l the cove in tlie shoj). whidi

is drawn hy coni]>lcting a s(|uare a I) c d. I )raw

the diagonal h d at 4o°, which pn)ves tlie

s(|iiare; and, using d as a center, draw tlie

(|uarter-(ir(le a c

In Fig. 271, 1) represents the ovolu or

rchinun, known in the shop as the (juarfcr-

rnund, which is con.stnicted similarly to C in

Fig. 270, witli the c.\cej)tion that h in Fig. 271

is use<l to obtain the curve ac.

E in Fig. 272 is known as the torus, known in the shop as a bead-

mould. A given distance a b is bisected, thus obtaining c, which is the

center with which to describe the semicircle a b.

All of tiiese pn)filesshould be drawn by the student to any de-

sired scale for practice.In [)reparing mouUlings from sheet metal,

FiK. 27.>.

V\k. -27^.

it is somehnuvs m|uirrd tiiat iiirirlinieiils are added in the t)giH', cove,

and bead. In that case the mould must be bent to; receive these en-

richments, which are iisiuilly obtaine<l fmm dealers in stanipe«l »»r

pressed she<'t-metal work. Thus, in Fig. 273, F reprvsents a front

view of a crown mould who.s»j oget? is enriehetl. tlw; .section of tlie e»j-

2.15


richment being indicated by a 6 in the section, in which the dotted Hne

d c shows the body of the sheet-metal uioukUng bent to receive the

pressed work. In Fig 274, H represents i)artof a bed-mould in which

Fig. 274.

egg-and-dart enrichments are placed. In this case the body of the

mould is bent as shown by cd in the section, after w^iich the egg-and-

dart is soldered or riveted in position. J in Fig. 275 represents part

Fig. 275.

of a foot-mould on which an enriched bead is fastened. The body of

the mould would be formed as indicated by c in the section, and the

bead a b fastened to it. This same general method is employed, no

matter what shape the pressed work has.

PRACTICAL MITER CUTTING

Under this heading come the practical shop problems. The prob-

lems which will follow should be drawn to any desired scale by the

student, developed, and bent from stiff cardboard to prove the accu-

racy of the pattern. If the student cannot use the small brake in the

shop and test his patterns cut from metal, he can use the dull blade of

a table knife, over which the bends can be made, when using cardboard

patterns. This at once proves interesting and instructive. Should

there be any problem which is not clear, he should write at once for

further information; or, should any problem arise on which he desires

236

SllKKT MlCr.VL WOltK J(I5

iiifdniialioii, ilic School will iiiforiii liiiii wliicli |trol)leiu in liis text-

l>«N»k.s coiitaiiis similar|)riiici|)U's.

or will prrpart' such a pnihlein for

liiiii.

The lirst|>rol)lciii

will Ik* to ohtaiii the (Icvclopiiientof a .stjuare

return iiiitcr. such as would occur when a inoiiltliii;; hail to return

around the nirner of a l)uililinj(, lus shown in Fij;. 27t). In Fij:. 277

are shown two methods of ol)-

taiiiinjj the|»attcrii. The first v^ '

.1

method which w ill he descriheil \is the "lon^" inetluHl, in which ^

are set forth all the |)rinci{)les \ j

apjilicalile to olitaiuing pat-

terns for niouldin<;s, no matter ^'^^- -'*'

what ani,'le the plan may have. The second method is the "short'

ELEVATION

I

II

I

II' 10 9 8 7'6'5'4'3' Z' l' 'h'

'

l-ig "V7

a:n


rule generally employed in the shop, which, however, can be used onlywhen the angle H G F in plan is 90°, or a right angle.

To obtain the pattern by the first niethotl, proceed as follows:

First, draw the elevation of the mould as shown by 1, B, A, 11, drawingthe coves by the rule previously given. Divide the curves into equal

spaces; and number these, including the corners of the fillets as shown

by the small figures 1 to 1 1. In its proper position below the elevation,

draw the soffit plan as shown by C D E F G H. Bisect the angle H GF by the line G D, which is drawn at an angle of 45°. From the va-

rious intersections in the elevation, drop lines intersecting the miter-line

as shown. At right angles to H G, draw the stretchout line 1' 11',

upon which place the stretchout of the mould 1 11 in elevation, as

shown by similar figures on the line 1' IT. At right angles to 1'

11', and from the numbered points thereon, draw lines, which intersect

by lines drawn at right angles to H G from similarly numbered inter-

sections on the miter-line G D. Trace a line through the intersections

Fig. 278.

thus obtained, as shown by J G. Then will 1' G J 11' be the desired

pattern. This gives the pattern by using the miter-line in plan.

In developing the pattern by the short method, on the other hand,

the plan is not required. At right angles to 1 B in elevation, draw the

stretchbut line 1" 11", upon which place the stretchout of the profile

1 11 in elevation, as shown by similar figures on 1" 11", at right

angles to which draw lines through the numbered points as shown,which intersect by lines drawn at right angles to 1 B from similarly

numbered intersections in the profile in elevation. Trace a line through

points thus obtained, as shown by G K. Then will G 1" 11" K be

similar to J G 1' 11' obtained from the plan.

238

.^iii:i:'i Mi;i'AL wouk 207

In Fijj. ?78 is shown a hurizontal mmiUling l»utliim Jigaiiist a

plane surfatr oljlitjue in elevation. A miter cut <»f this kind would

be re<|uired when the return nioiilriinj^ of a ilonner window woidd butt

against a mansard or other pitclietl roof. In this case we a.ssunie AUi be the return liuttinj; Ji^jainst the pitched roof U. The luetljocl of

PATTERN

Fig. 'JTU.

obtaininp; a pattern of this kind is shown in Ki^'. LT'.t. I,i-t .\ 1? (' |)

represent tlie elevation of the return. .\ 1 )n'j»resentin>,'

thepitcli

of the

nxif. In its proper position as shown, draw the .section 1 II. which

diviilc into e<|ual spaces as .sliowii. and fn)m which, paralh'l ti» A H,

draw hues intersecting,' the shmt hiic A 1) fn)m 1 to 1 1, as .sliown. At

right atigh's to A H erect th»' stretchout hue 1' 11', ujM>n which phuvthe stretchout of the s«-«'tinii as shown b\' similar li;4un's on 1' 11'.

At right angles In I' 11', and thniugh the ninnbcrcd jMiints tiiertiin,

tlraw lines, which intenjcci by lines drawn at right angles to A li fn»in

similarlv tnnnberc<l intersections on the slant line \ I' Through

^S9


the various intersections thus obtained, draw E F. Then will E F11' 1' be the desired pattern.

It is sometimes the case that the roof against which the moulding

butts, has a curved surface either concave or convex, as shown by B Cin Fig. 280, which surface is convex. Complete the elevation of the

moulding, as D E; and in its proper position draw the section 1 9,

which divide into equal spaces as shown by the small figures, from

which draw horizontal lines until they intersect the curved line B C,

which is struck from the center point A. At right angles to the line

of the moulding erect the line 1' 9', upon which place the stretchout

SECTION

c

Fig. 280.

of the section, as shown by the figures on the stretchout line. Throughthe numbered points, at right angles to 1' 9', draw lines, which

intersect by lines drawn at right angles to 2 D from similarly numbered

intersections on the curve B C, thus resulting in the intersections 1" to

9" in the pattern, as shown. The arcs 2" 3" and 7" 8" are simply repro-ductions of the arcs 2 3 and 7 9 on B C. These arcs can be

traced by any convenient method; or, if the radius A C is not too longto make it inconvenient to use, the arcs in the pattern may be obtained

as follows: Using A C as radius, and 7" and 8" as centers, describe

arcs intersecting each other at A';in similar manner, using 2" and 3"

as centers, and with the same radius, describe arcs intersecting each

240

SHELT MKIAL WuHK 2(W

otiier at A . With the same nulius. ami with A' and A' as ct-uters.

ilraw the ares S" 7" and .)" 2" respeetively. Traee a hue through

the other various intersections as shown. Then will I' 1" 'J" 9' l>e llie

desiretl pattern.

In Fi<j. "J-Sl is shown an elevation of an oblong or rectangular

panel for which a miter-cut is desired on the line a b—known its a

"panel" or "face" miter. The

rule toaj)j)ly

in ol)taining this

pattern is shown in Fig. 2S2.

A shows the jjartelevation of 1

the panel; a h and c <l, the

miter-lines drawn at angles of

45°. In its proper position

with the lines of tiie mouM-

ing, draw the pn)Hle B. the

cun'eor mould of which divide

into ef|ual spaces, as shown

hy the figures 1 to 7; and fn)iu

the poHits thus obtained, par-

allel to 1 h, draw lines inter-

I-iR. •Jsi. liK. JSJ

.seeling the miter-line a h as shown. From the.se intersections, par-

allel to /) (I, draw line-s intersecting also ril. At right angles to bd

draw the stretchout line 1' 7'. upon which plai-e the stretchout of the

pndih' n. At right angles to 1' 7', and through the nundiertnl

)M)iiitsof divi>-ion. <lraw lines, which intersect by lines drawn at right

angles to It d fnmi similarly numbere<l intersiH-tions on the nuter-

lines (I b anti r d. Trace lines through the various |M>ints <»f inter-

section in the pattern a.s shown. Then will ( 1> 1', 1' be the re«|uin*<l

cut for the enils of the panel.

The same miter-<'Uts would be employnl for the long side u c in

•,;»i


Fig. 281, it being necessaiy only to make D E in Fig. 282 that length

when laying out the patttern on the sheet metal.

Wliere the miter-cut is required for a panel whose angles are other

than right angles, as, for example, a triangular panel as shown in Fig.

283, then proceed as shown in Fig. 284. First draw the elevation of

the triangular panel as shown by A B C, the three sides in the case

being equal. Bisect each of the angles\A, B, and C, thus obtaining the

miter-lines Ac, B 6, and C a. In line with the elevation, place in its

proper position the profile

E, which divide into equal

spaces as shown; and from

the numbered division

points, parallel to A C, draw

lines cutting 'the miter-line

C a. From these intersec-

tions, parallel to' C B, draw

lines intersecting the miter-

line. 6 B. At right angles to

C B draw the stretchout line

V T, upon which place the

ELEVATION

Fig. 283. Fig. 284.

stretchout of the profile E. Through the numbered points of divi-

sion and at right angles to V 7', draw lines as shown, which intersect

by lines drawn at right angles to C B from intersections of similar

numbers on the miter-lines a C and h B. Through the points thus

obtained, trace the pattern F G H I.

It makes no difference what shape or angle the panel may have;the principles above explained are applicable to any case.

In ornamental cornice work, it often happens that tapering mould-

ed panels are used, a plan and elevation of which are shown in Fig. 285.

242

SIIKKT MinWI, WOHK 211

My rt'ffrriiif; to the plan, it will In- swii that the four parts h a, a b', h' a',

ami «' b are syinmetrical; tlicrefoR*, in practice, it is riei-exsan.- only to

<lra\v the one-<juartcr plan, as shown in Fij^. 2.S(), ami otnit the eleva-

tion, sinc-e the height d v (I'V- 2^3) is known. Thus, in Fig. 280, draw

the (juarter-plan of the |)anel. no matter what is its shape, as shown

1m«. 2,S.5.

by a 15 fi 0. Divide the curves from 1 5 and 9 into ofjiia-

spaces, indicated respectively hy 1, 2, 3, 4, and o, and (», 7, S. and '.t.

Fn)ni tiiese jxtints, draw lines to the apex a. As the ])attern will he ile-

velojxxi by triangulation, a set of trian<,'les will he rcnpiireil. as shown in

I'lK. -'sti.

Fi^. 2s7, fur which procccil as follows: Diaw any horizontal line, ns

n I; and fi-orn a erect the perpendicular (i «' npial to the height the

panel is to havi-. Now take tlu> lengths of the \arious lines in Fig. 2S(»

fn)in It to I, rj to 2, a to 3, etc., to a to<), and place iheni on the line o 1 in

Fig. 2S7, a.s .shown l»y similar ninnhers. Then using as radii the vari»)us

843


lengths a' 1, a' 2, a' 3, etc., to a' 9, and with any point, as a' in Fig.

288 as center, describe the various arcs shown from 1 to 9. From any

point on the arc 1 draw a Une to a'. Set the dividers equal to the

spaces contained in the

curve 1 5 in Fig. 286; and,

starting from 1 in Fig. 288

step from one arc to an-

othcx having similar num-

bers, as shown from 1 to 5.

In similar manner, take the

distance from 5 to 6 and^' '

the spaces in the curve 6 9

in Fig. 286, and place them on corresponding arcs in Fig. 288, step-

ping from one arc to the other, resulting in the points 5 to 9. Trace

a line through the points

thus obtained. Then r

will a' 1 5 6 9 a' be the

quarter-pattern, whichcan be joined in one-

half or whole pattern as

desired.

In Fig. 289 is shown

a perspective of a mould-

ing which miters at an

angle other than a right angle. This occurs when a moulding is

required for over a bay window or other structure whose angles vary.

The rule given in Fig. 290 is applicable

to any angle or profile. First draw a

section or an elevation of the moulding

as shown by A B 14 1. Directly below

the moulding, from its extreme point,

as 2 3, draw a plan of the desired

angle as shown by C 2 D. Bisect this

angle by using 2 as center and, with

any radius, describing an arc meeting

the sides of the angle at C and E. With the same or any other radius,

and with C and E as centers, describe arcs intersecting each other in F.

From the corner 2, draw a line through F. Then will 2 H be the

Fig. 288.

Fig. 289.

244

initor-l

|)n>tile

inc. or ilip line l)ist'ctinf? tlip aiifjle ('2 1). Xow iliviile the

1 14 into vt[un\ .s|)ac'e.sas sluiwu by tlie figures, and from tlie

tlius obtainetiilitjp vertical line.s intersprtintj the miter-line 2

I \

111

-\

: :•:;:

,,1 , 1

1 .1 1

'

I

'

I .

12

ELEVATION

13l|-i

-B

(4 n lail 109 8 7 6 5 4 T p I

PATTERN"M

Fig. 290.

II in plan from 1 to 14 a.s .shown-

At ri^'ht angles to (' 2. draw the

line I K, n|K)n which place the

stretchout of the|)rofile

in elevation

a.s .shown by similar figures on the

stretchout line, through which droplines |K'rpendicular to .1 K, which

intersect with linivs drawn parallel

to I K from similarly mnnb«'nHl

|M>int.sof intersection on the miter-

line _' II. Traci- a line as shown liyI- M, which is the miter-<'ut

desired.

\N hen two mouldings having dilTercnt j)roliles are reipiin^l to

miter lt)gelhcr lus .slu»wn in Fig. 2*.H. where (' miters at right angles

24.^


with D, two distinct operations are necessary, which are clearly shown

in Figs. 292 and 293. The first operation is shown in Fig. 292, in

which C represents the elevation of an ogee moulding which is to

miter at right angles with a moulding of different profile as shown at D.

Divide the profile C into equal

2 spaces, from which points draw

horizontal lines intersecting the

moulding D from 1' to 10'. At

right angles to the line of the

moulding C, draw the line A B,

upon which place the stretchout

of the profile C as shown by simi-

lar figures on A B. At right

angles to A B, and through the

PATTFRN FOR

Fig. 292.

points indicated by the figures,

draw lines, which intersect with

lines drawn parallel to A B from

similarly numbered intersections

in the profile D. Trace a line

through the points thus obtained,

as shown by E H. Then will EF G H be the pattern for C in

elevation.

To obtain the pattern fori),

draw the elevation of D (Fig.

Fig. 293.

293), which is to miter at right

angles with a moulding whose profileis C. Proceed in precisely

the same manner as explained in connection with Fig. 292. Divide

the profile D in Fig. 293 into equal parts, as shown, from

which draw horizontal lines cutting the profile C. At right angles

246

siiKtrr MhrrAL wouk 21;

Fig. 291.

to till- liiu's tif till- moiiltliii;; D, ilraw llif >tri't(li«)Ht liiu- A IJ, iijm»ii

wliith place the stretclioiit of tli«' pnilik' I). At ri}^lit uii^U's to A B,

anil thniiigh tlie iuiiuIhtc*! points of ilivisioii, ilruw lines its shown,

which intersect hy Hnesdniwii parallel to A M fruni similarly nunil>ere«i

intersections in the profile ('. 'riirou^'h these |)oints of intersection

• Iraw F ( ;. Then will E F G II he the clesire«l pattern for I ).

It shoulil he understood that when the |)atterns in Fifjs. 202 and

203 are fonned antl joine<l together, they will form an inside miter, as

is shown in Fig. 201.

If, however, an outside

miter were refjuired, it

wouKl he neccssar}' only

to \ise the reverse cuts of

the patterns in Figs. 202

and 203, as shown by E J

II in Fig. 202 for the

mould C, and F J G in

Fig. 203 for the mould D.

Whenjo i n i n g a

curved moulding with a straight mouUling in either plan or eleva-

tion even though the cur%ed or .straight mouldings each have tlie

same profile, it is neces.sar}- to estal)lish the true miter-line before

the pattern can be correctly develojied, an example being given in

Fig. 204, which shows an elevation of a curvtnl moulding which

is intersecte<l by tlje horizontal mouldings A H. The method of ol>-

taining this miter-line, also the pattern for the horizontal pieces, is

clearly shown in Fig. 20.'). First draw the pn)iile whiih the horizontal

moulding is to have, as 1 10. Let the distance H be e.stablisluMl.

Then, with (" on the center line as center, and .V ("as ra<lius, describe

the arc B A. From any point on the line H, as n. erect the vertiinl

line in 1 to 10 asshowii.

From the center (', draw any radial line, as (

'

d, cutting the arc M A at e.

Now take tin- various divisions on a /», and place them from e to </ jus

shown bv points 1' to 10'. Then, using (' its center, with radii deter-

niineil bv the various jioints on r d, dniw arcs intersecting horiz«»ntal

Urn's of similar mu'diers drawn through the divisions on a b. Through

1247


these points of intersection, draw the miter-Hne shown. The student

will note that this line is irregular.

Having obtained the miter-line, the pattern is obtained for the

horizontal moulding by drawing the stretchout line E F at right angles

to 9 B. On E F lay off the stretchout of the profile 1 10; and

through the numbered points and at right angles to E F, draw hori-

zontal lines, which intersect with lines drawn at right angles to 9 Bfrom similarly numbered in-

a'. tersections in the miter-line

determined by horizontal lines

already drawn through the

vertical line a b. Trace a line

through the points thus ob-

tained, as shown by H I J K,

which is the desired pattern.

AB

Fig. 296.

In Fig. 296 is shown a shaded view of a gable moulding intersect-

ing a pilaster,the gable moulding B cutting against the vertical pilaster

A, the joint-line being represented by a 6 c. To obtain this joint-line,

without which the pattern for the gable moulding cannot be developed,

an operation in projection is required. This is explained in Fig. 297,

in which BCD shows the plan of the pilaster shown in elevation by E.

In its proper position in plan, place the profile of the gable moulding,

as shown by A, which divide into equal spaces as shown by the figures

1 to 8, through which draw horizontal lines intersecting the plan of the

pilasterB C D as shown by similar figures. For convenience in pro-

248

SlIKKT MKTAL WoHK 2l'i

jectiiij;till' varu)ii.s

|x)iiil.s,and to avoid a coiifusion of lines, number

the intersections between the Hnes «lrawn from the pntfile A llirougfi

the wash H 2. "7°". "4°", an<l *':{^'. At the (h-sired in.int II in eleva-

ti«)n, draw the lower hne of the j;able mouldinij, a.s II I". Take a

traeini; of the])roliU'

A

in phin, with all of the

various intersections on

>anie, and j)laceit in

elevation as shown by

A', placing the line 1 S at

rifjht an^^les to II V.

'riiroufjh the various in-

tersections 1, 7°, 4°, 3°.

2, 3, 4, o, <), 7. and S in

A', and |)arallelto F 11.

draw lines indefinitely,

which intersect by lines

drawn at ri^dit an<jles to

(" H in plan fnini sim-

ilarly numbered intersec-

tions in the pilasterT I)

H, t h 11 s obtainini: the

[)oints of intersection 1"

to S* in elevation.

For the pattern, j)ro-

(cvA as follows: At rij^ht

angles to II F, draw the

^t^•tchout line .1 K, uponwhich place the stretch-

out of the pn)(ile A or .V,

with all the points of in-

tersection on the wash

I 2. At ri/;ht anodes to I K, and through the nuntber«Nl j>oints, draw

lines as shown, which intersect by lines drawn at rij;ht anj^les to II

I'' fn)m similarlv numbered inlerse<-tions in the j«>int-line l" S*

Throu^'h the points thus obtained, trace iIm- miter-cut M N ( >. 'I'hen

will I, M \ ( ) I' be the pattern for tlu- jjable mouldiiifj.

In Fiy.29S are shown pable mouldings miterinn uj)on a wash. The

•jji»


mouldings A A intersect at any desired angle the wash B. In this case,

as in the preceding problem, an operation in projection must be gone

through, before the pattern can be obtained. This is clearly shown

in Fig. 299. Draw the section of the

horizontal moulding B^ with the wash

a b. From this section project lines,

and draw the part elevation D C.

^^S- ^^^-Knowing the bevel the gable is to

have, draw C B, in this case the top line of the moulding. Draw a

section of the gable mould, as A, which divide into equal parts as

shown from 1 to 8; and through the point of division draw lines

parallel to B C, indefinitely, as shown. Take a tracing of the profile

A, and place it in section as shown by A'. Divide A into the same

PATl

SECTION ELEVATION

Fig. 299.

number of spaces as A; and from the various divisions in A* dropvertical lines intersecting the wash a 6 as shown, from which points

draw horizontal lines intersecting lines drawn parallel to B C

through similarly numbered points in A, at 1° to 8°. Trace a line

through these intersections as shown, which represents the miter-line

or line of joint in elevation.

For the pattern, draw any line as E F, at right angles to B C, uponwhich place the stretchout of the profile A, as shown by similar figures

on the stretchout line E F, Through the numbered pomts of division

and at right angles to E F, draw lines as shown, which intersect by

250

SIIKK'I MKTAL WOHK 219

!b/A r!

.-J

A

FiK. 300.

lilies tlrawii at rij^lit an;,'lr.s ti» |{ (' fnmi similarly niiiiiltertti iiUersec-

tioiis on 1° ff anil on tlu- vertical line 15 1). A line trace«l tlinrnj^li

|)oiiit.s thii.sc)l)taine<l, as shown Ity< i 1 1 I I, uill he tiiedesiretl pattern.

Ill Fifj. 30() is shown a fnjiit view «)f a turret on which four j:aljles

are to he i)hice<l, as shown hy A A; also the nnifs

over same, as shown hy B B. The j)n)hleni con-

sists in ohtaininjj the developments of the jjahle

moiihlinfjs on a square turret. In developingthis pattern, the half-elevation only is rtH|uire<l,

as shown in Fig. 301, in which first draw the

center Hne E F; then cstahlish the half-width of

the turret, as C I), and draw the rake B C. At

riuht annjles to tlic line B ( '. and in its j)n)j)er

position as shown, draw the prf)file .\, whicji

divide into ef|ual spaces as shown hy the Hjjures

1 lo 0, throuj^h which, parallel to B C, draw lines intersecting the

center line F E as shown; and extend the lines helow (", indefinitely.

Now take a tracing of the profile A, an<l place it in position as

shown hy A*, heing careful to have it spaced in the same numher of

divisions, as shown from 1 to 6, through which, j)aralk'l to D C, erect

lines intersecting similarly numhered lines drawn through the pmfile

A, thus ohtaining the intersections 1° to G°, through which a line is

traced, which represents the line of joint at the lower end hetween

the two gahles.

For the j)attcrn, take a stretchout of A. and |)lace it on the line

J K drawn at right angles to B C, as .shown hy the figures 1 to ('» on .1 K.

At right angles to .1 K, and through these p«)ints of division, draw lines,

which intersect hy lines drawn fn)m similarly numhere<l interstx-tions

on 1" li anrl 1'' (')°. 'Trace a line through the |)oints thus ohtaine<l,

as shown hy 1*^ B° C° 0°, which is the desire«l |)attern, of which eight

are rciiuin-d to complete the turret, four formol right and four left.

If the roof shown hv B in Fig. '.)()() is desire<l to he addetl to the

pattern in Fig. .'{(ll. then, at right angles to V^ (l®, draw the line P F'

ejpial to F II in the half-elevation, and draw a line frum F' to ••'^ in the

pattern.

In Fig. 302 is shown front vij'wof an angular pnlinient with lu)ri-

zontal returns at l)ottom .\ and top H. In this pntl>leiii,as in othets

which will follow, a change of pn)lile is ne«'e."vsaryi)efon' the otrreet

S51


pattern for the returns can be developed. In other words, a new pro-

file must be developed from the given or normal profile before the pat-

terns for the required parts can be developed. It should be under-

stood that all given profiles are always divided into equal spaces; there-

fore the modified profiles will contam unequal spaces, each one oi

^i

I HALFI ELEVATION

Fig. 301.

which must be carried separately onto the stretchout line. Bearing

this in mind, we shall proceed to obtain the modified or changed pro-

files and patterns for the horizontal returns at top and foot of a gable

moulding, as at B and A in Fig. 302, the given profile to be placed in the

gable moulding C. In Fig. 303, let C represent the gable moulding

2.52

I

I

I

MiKivi' Mrr\i.\vr)nK 221

^.

FiK. 303.

nljKtil at its pn)pcr an^'lo with tlie Imri/ontal iiiouldiiitj (ill. As.smu-

iiij; that (»" <)° is the prujuT an<jU'. place the ^iveii pn>file A at right

aiij^le.sto the rake. a.>< .shown; and divide .same into e<jiial .spaces as

.shown fmm 1 to U). thn)U^h wliich|)«>int,s, parallel to 6* O**, draw lines

towards the top and hottom of the

rakiiif^ nionldin<;. .V-ssuniin^ that the

lenj^th ('»" ()*' is t-orreet, take a tracing;

of the j)rofile A. an<l j)la(e it in a ver-

tical |)ositionl)elow at A' and al)ove

at A-, hein^' larefiil t«» have the jjoints

(i and (1 in the j)n)files directly ''n a ver-

tical position below the jiointsVi^ and ()°, as .shown. From the va-

rious intersections in the profiles A' and A" (which mu.st contain tlie

same ninnber of spaces as the fi:iven j)rofile A), erect vertical lines

intersectinj; lines drawn through the j)rofile A, as .shown at the lower

end from P to lO'', and at the ui)per end from 1° to K)®. Trace a line

througli the points thus obtained. Then will P lO'^ be the modifie«l

|)n)hlefor the lower horizontal return, and 1° 10° the moditietl prt)file

fur the upj)er liorizontal return.

Note the difference in the shapes an<l sj)aces between these two

modifie<l profiles and the jiiven j)roHlc .\. It will be notice<l that a

portion of the gable moulding miters on the horizontal moulding (I II

from (\^ to 10'.

For the jiattern for the gable moulding. j)roceetlas follows: At

right angles to K F, draw the .stretchout line .1 K, u|x)n which place

the stretchout of the given pri)(ile A, as shown by the fig\ires 1 to lOon

J K. Through these figures, at right angles to 1 K, draw lines as

shown, which intersect with lines drawn at right angles to V. V Inun

similarly lunuln-rcd intersections in 1° 10° at the top and T »•''

lO* at the lower cud. Tra(«> a line lhr..,igii th<- infersecticuis thus ol>-

tained. Then will 1 , M N ( ) bi- tlic pattern I'm- ( '.

Vov the p.ittiTM for tile horizontal rt'turn at thetoj». draw aside

view as .^howii at H, making I' K the desired |)rojection.and the pntlile

1 10 «»n H. with it.s various intersections, an «'\act n-pnxluction of

1° 10° in the «'Ievation. Extend the line K T as II ."-1; an«l. starting

from 10. lay off the stretchout of thepr«>lile

in H as shown by the figures

I to 10 i>n U S. being careful to measure each spa«-e separately. At

right angle-, to U .-^ ilraw tin- usual measuring lines, which intersect

a&.i

by lines drawn parallel to S R from similarly numbered points in the

profile in B. Trace a line through points thus obtained. Then will

U V 10 1 be the pattern for the return B.

In similar manner, draw the side view of the lower horizontal

return as shown at D, making the projection W 10 equal to P R

— ru <n ^ m coNqj o>9 (-

COoCO

S

— (\iir)tu)<ot^ia o)2 X

in B. The profile shown from 1 to 10 in D, with all its divisions, is

to be an exact reproduction of the profile 1^ to 10^ in elevation. Extend

the line W' X as X Y, upon which lay off the stretchout of the profile

1 10 in D, being careful that each space is measured separately,

as they are all unequal. Thiough the figures on X Y draw lines as

254

'IIHET METAL WOHK i23

shown, which intersect by hnes<h'awii paruHel Ui W \ from tl»e variou.s

intersections in tlie profile in the side I). A Une traced thnuigh jMjints

thus ohtainetl, as shown hy Z V, will he t]ie desired cut, and 1 Z\' 10 the pattern for the return D.

In Vi^. 304 is shown a front view of a segmental pe<liment with

upper and lower horizontal returns.

'I'his presents a pn)l)lem of obtaining'

the pattern for horizontal returns at

to[) and foot of a segmental pediment,shown respectively at A and H. the

given profile to be place^ '*'"

j)rinciples usetl in obtaining these patterns are similar to tliose

in tlie preceding problem, the only difTerence being that tlie moid<l-

ing is curved in elevation. In Fig. 305 the true method is clearly

given. First ilraw the center line B D, through which draw the horizon-

»^ -^--H

tal line (' f ''. Fn)m the line (" C establish the heigiil K

,ami with the

dcsire<l center, a.s H, draw the arc ]•] (*

interse«ting the line (' (' at (',

In its proper |M)sitionon a vertical line F (1. parallel to I) H, draw the

^^ivcn pnililc of the cuncd moulding as shown by A, which divide int«»

e<pial .spaces as .shown fmm 1 to 10. Through tlu'se (igures. at right

iinjjles to F (i, draw lines intersecting the center line 1> H as shown.

fins


Then, using B as center, with radii of various lengths corresponding

to the various distances obtained from A, describe arcs as shown, ex-

tending them indefinitely below the foot of the pediment. The point

C or 6" being established, take a tracing of the profile A, with all the

various points of intersection in same, and place it as shown by A^

being careful to have the point 6 in A^ come directly below the point

6" in elevation in a vertical position. Then, from the various inter-

sections in A- erect vertical lines intersecting similarly numbered arcs

drawn from the profile A. Trace a line as shown from 1" to 10",

which is the modified profile for the foot of the curved moulding.

Establish at pleasure the point V at the top, and take a tracing

of the given profile A, placing it in a vertical position below 1', as

shown by A^ From the various

intersections in A^ erect vertical

lines intersecting similarly num-

bered arcs as before. Throughthese intersections, shown from

T to 10', trace the profile shown,

which is the modified profile for

the top return.

The curved moulding shown

in elevation can be made either

by hand or by machine. The

general method of obtaining the

blank or pattern for the curved

moulding is to average a line through the extreme points of the

profile A, as I J, extending it until it intersects a line drawn at right

angles to D B from the center B, as B H, at K.

We will not go into any further demonstration about this curved

work, as the matter will be taken up at its proper time later on.

To obtain the pattern for the upper and lower return mouldings,

proceed in precisely the same manner as explained in connection with

returns B and D in Fig. 303.

In Fig. 306 are shown the plan and elevation of a gable moulding

in octagon plan. This problem should be carefully followed, as it

presents an interesting study in projections; and the principles used in

solving this are also applicable to other problems, no matter what

angle or pitch the gable has. By referring to the plan, it will be seen

256

SIlKE'l" MK'IAL WuitK 225

that tlif moulding has an octuf^on aii^lr in plan u h c, while .similar

points in elevation «' // c' run on a rake in one line, the top aiid foot

of tlie moulding hutting against the hriek piers li an«i A.

The method of pHx-ettlin^ with work of this kind is exjjlained in

detail in V'\i^ 307, where the principles are thoroii<,'hly explained. Ix't

A H <

'

I• 1. represent a plan view of the wall, over which a j^aM*

muuldinu is io be placed, as shown hv yI, M. 1 )ivi(io tlir profile into equal spact»s

ns shown liv the li^'iiri>s 1 to s. Parallel to 1 II or .1 (J. and thn>ui;h ihe

fi^'ures mentioned, draw lines imlclinitely as shown. Bisect the ai^jle

H (

'

f ) in |)lan.and obtain the miter-line as follows: With (' jis center,

and anv radins, describe the arc N ( ). With N and ( ) as centers, and

unv radins jfreater than (' N or (' (). describe an-s intersiftinj; each

other at r I'ntm the point ('. and lhron^;h the interseition 1*. draw

die miter-line <

'

t^. Transfer the piiililcI - M in elevation to the

|M»si-

ijft?


tion shown by R S in plan, dividing it into the same number of spaces

as L M. Through the figures in the profile R S, and parallel to D C,

draw lines intersecting the miter-line C Q, as shown. From the inter-

sections on the miter-line, and parallel to C B, draw lines intersecting

the surface B A. Now, at right angles to C D in plan, and from the

SOFFIT PLAN

Fig. 308.

intersections on the miter-line C Q, draw vertical lines upward, inter-

secting lines of similar numbers drawn from points in profile L M in

elevation parallel to J G. A line traced through points thus obtained,

as shown from 1' to 8', will be the miter-line in elevation.

For the pattern for that part of the moulding shown by C D E Q'in plan, and H G 8' 1' in elevation, proceed as follows: At right

angles to 1 H in elevation, draw the line T U, upon which place the

258

SIIKK'I' MK'I'M WORK 227

.stretchout of the pniHIe I^ M, as shown hy the Hj^ures 1 to S. At rij^ht

iii»i;h's to 'I' r, and throuf^h these figures, draw lines, as shown, wliich

intersect with Hues of siinihir nunihers drawn at rij^ht anjj;les to 1 H

from intersections on the niiter-line 1' S' and fnjni intersectioas

against the vertical surface H (J. Lines trace<l through jxtints thus

ol)taine<l, lus shown l)v \' \V X Y, will he the jiattern for that|)art

of

the gahle shown in plan by C U E Q' of Fig. '.0)7.

In Fig. .'iOS, on the other hand, the j)ositionof the plan is changed,

so as to hring the line A Q horizontal. At right angles to \i T draw

the vertical line f E, on which locate any |X)int,as K. In the same

manner, at right angles to C B, draw the vertical line B J intlehnitely-

Fr')ni the point E, parallel to B C, draw the line E S", intersecting

the line J B, as shown. Now take the distance from S" to J in eleva-

tion, Fig. 307, and set it off from S" toward J in Fig. 'MS. Draw a line

fn)m J to E, which will represent the true rake for this |Mjrtionof the

moulding. Now take the various heights shown frt)m 1 to S on the

line Z Z in elevation in Fig. 307, and i)lace them as shown hy Z Z in

elevation. Fig 30S, being careful to jilace the point S of the

line Z Z on the line S" E extended. At right angles to Z

Z, and from points on same, draw lines, which intersect

with lines drawn at right angles to B C from intersec-

tions of similar numbers on C Q in plan. A line trace«l

through points tlius obtained, as shown by D E in eleva-

tion, will be the miter-line on C Q in plan.

From the intersections on the miter-line I) E, and

parallel to E J, draw lines, which intersect with lines

drawn from intersections of similar mnubers on A B in

j)lan at right angles to B C. A line traced through jwiints .^.^—^

thus oi)taineil, as shown by F J, will be the miter-line ''K- ''^^^

or line of joint again.st the pier shown in plan by B A.

Before obtaining the pattern it will In- necessary t«> obtain a true

section or |)rolile at right angles t«) the moulding F 1 >. To «lo so, pro-

ceed lus follows: 'i'ransfer the given pi"olilcI. M in elevation in Fig.

307, with the divisions and figures on sanu-, to a position at right angles

to F i ) of Fig. 30S, as .shown at I.. At right angles to F D. and fn)nt

the interstM-tions in the |>ro(ile E, draw lines inter.se<-ting those of sinii-

iar n(Miil)ers in F 1 ) I'' I. Trace a line fhn)Ugh interse<"tions thus ob-

2an


tained, as shown from 1 to 8, thus giving the profile M, or true sections

at right angles to F D.

For the pattern, proceed as follows: At right angles to F D,

draw the line H K, upon which place the stretchout of the profile M, as

shown by the figures. At right angles to H K, and through the figures,

draw lines, which intersect with those of similar numbers drawn at

Fig. 310. Fig. 311.

right angles to F D from points of intersection in the miter-lines D Eand J F, as shown. Lines traced through points thus obtained, as

shown by N O P R, will be the pattern for the raking moulding shown

in plan, Fig. 307, by A B C Q'.

In Fig. 309 is shown a view of a spire, square in plan, intersecting

four gables. In practice, each side A is developed separately in a

manner shown in Fig. 310, in which first draw the center line through

the center of the gable, as E F. Establish points B and C, from which

260

WEE'V MK'l'AL WollK 229

e

SIDE

tlraw lines to the apex V. At pleiLsure. estal)li.sli A 1 ). At right angles

to F K, aii«l fmiii H ami .1, draw the lines H II antl J K respectively.

For the pattern, take the distances B K. K A, and A F, and place them

as shown hy similar letters

on the vertical line B F in^

Fi-:- ^11. At right angles B

to ]{ F. and thnuigji points

H and A. draw lines as

shown, making B II and li

II' on the one hand, and

A X an«l A O on the other

hand, etpial respectively to

li II anil A X in elevation in

Fig. 310. Til en, in Fig.

.-=*!

Fig. 312. Fig. MA.

31 1, draw lines fn)ni X to H to K 1o fl' to O. its shown, which repre-

sents the j>attern for one side.

In Fig. 312 is .shown a perspective view of a drop B mitering

against the face of the bracket (' as indicated at A. The princij)le.s

for developing this prohleni are explaine<l in Fig. 313. and can he ap-

|iliip or hrneket

may he. Let .\ B (' 1) F represent the faceor fn)nt view of thehnieket

droj), and I" 1 1y the figures 1 to 7

on either side, from which points draw hori/onial lines cro.>vsing II (i

in sid«- view and intersecting the face II I of tlu* hracket at points 1' t<»

7'. In line with IH!, ilraw tlu- line .1 K, n|M»n which place the stretch-

out of the profile B <1 », as shown l>y

1 to 7 to 7 to 1 on .1 K. .\t right

angles to .1 K, draw the usual measuring lines a.s shown, which inter-

.sect l»y lines drawn parallel to ,1 K fmm similarly mnnlu'n'd inier.iM'^

tions on II 1. Tra<-e a line through the|M)int.s

thus ol)|aine<l. Then

2i\\


ELEVATION

Fig. 314.

will J K L be the pattern for the return of the drop on the face of the

bracket.

In Fig. 314, A shows a raking bracket placed in a gable moulding.

When brackets are placed in a vertical position in any raking moulding,

they are called "raking" brackets. B represents a raking bracket

placed at the center of the gable. The patterns which will be develop-

ed for the bracket A are also used for B, the cuts being similar, the only

difference being that one-half the

width of the bracket in B is

formed right and the other half

left, the two halves being then

joined at the angle as shown.

In Fig. 315 are shown the

principles employed for obtain-

ing the patterns for the side,

face, sink strips, cap, and returns

for a raking bracket. T h e s e

principles can be applied to anyform or angle in the bracket or

gable moulding respectively. Let S U V T represent part of a

front elevation of a raking cornice placed at its proper angles with

any perpendicular line. In its proper position, draw the outline of the

face of the bracket as shown by E G M O. Also, in its proper position

as shown, draw the normal profile of the side of the bracket, indicated

by 6-Y-Z-15 ; the normal profile of the cap-mould, as W and X;and

the normal profile of the sink strip, as indicated by 10 10' 15' 15.

Complete the front elevation of the bracket by drawing lines par-

allel to E O from points 7 and 9 in the normal profile; and establish

at pleasure the width of the sink strip in the face of the bracket, as at

J K and L H. To complete the front elevation of the cap-mould of

the bracket, proceed as follows : Extend the lines G E and M O of the

front of the brackets, as shown by E 6 and O 6, on which, in a vertical

position as shown, place duplicates (W^ W^) of the normal profiles Wand X, divided into equal spaces as shown by the figures 1 to () in W^

and W^ From these intersections in W^ and W^ drop vertical lines,

vhich intersect by lines drawn parallel to E O from similarly numbered

intersections in X, and trace lines through the points thus obtained.

Then will R E and O 1^ represent respectively the true elevations, also

262

SlIKKT MKTAl. WollK TM

tli< ii 111[ii.Mii.

-. i.ir tin- ivliirii.s at tup ami foot uf tin* cap of tin- rakiii^

lirackft.

Now tliviilo tliL- iiuriiial profile of the hraeket into etjual >pactrs, as

shown hy the figures G to 15, through which, parallel to E O, draw lines

intersecting the nonnal sink jirofilefrom 10' to l.V and tlie face lines

of the bracket KFt!. HI. KI.. and ( )NM, as shown. To obtain the

PATTERNf roR SIDEBRACKET

6'

icT-

e'WpATTET.lW^y FOR SINK

4' STRIP5'

PATTERN FOft/RETURN R E

. PAT T CRNFOR C

l-iK. 315.

true profile for the side of the bracket on the lino ( ).M and <JK, pro-

cet-il as follows: Parallel in ( )M, ilraw any line, as V Z'; and at right

angles to ()M, and from the variotis intersections on the same, dniw

lines indefinitely, crossing to the line V Z' as shown. Now, n»easuring

in each instance from the line VZ in the normal prolile.take the various

distances to points ti to 1.') an<l l.V to 10', and i>lace them on similarly

mnnbcred lines nteasnring in I'ach and every instance from the line

V Z', thus obtaining the points •'»' to 1.'.' and 1")" to 10", as shown.

Trace a line through the points thus cibtained. Then will V 0'

?''.>' 10' 1.')' Z' be the pattern for the side of the raking bracket,

tf<i»

232 SHEET METAL \WRK

and 10' 10" 15" 15' the pattern for the sink strip shown by the

lines K L and H J in the front.

For the pattern for the face strip B, draw any Hne, as A^ B', at

right angles to G M, upon which place the stretchout of 10 15 in the

nonnal profile, as shown from 10 to 15 on A^ B^ Through these

points, at right angles to A' B^ draw lines as shown, which intersect

with lines drawn from similar intersections on the lines F G and H J.

Trace a line through points thus obtained as shown by F° G° H° J°,

which will be the pattern for the face B, B.

For the pattern for the sink-face C, draw C^ D^ at right angles to

GM, upon which place the stretchout of 10' 15' in the normal profile

as shown from 10' to 15' on C^ DS through which, at right angles to

C* D\ draw lines, which intersect bylines drawn from similar intersections

on K L and H J. Trace a line through

the points so obtained as J° K° L° H°,

which is the pattern for the sink-

face C.

The pattern for the cap D and

the face A will be developed in one

piece, by drawing at right angles to

EO the line E^ F'. At right angles

Fig. 316. Fig. 317.

to E' F', and through the figures, draw lines, which intersect with lines

drawn at right angles to EO from similarly numbered intersections on

REF and NOP. A line traced through the points thus obtained, as

shown by R° E° F° and N° 0° P° will be the pattern for D and A.

For the patterns for the cap returns R E and O P, draw any line

at right angles to 1 1 in the normal profile, as H^ G', upon which

place the stretchouts of the profiles R E and O P, being careful to carryeach space separately onto the line H^ GS as shown respectively by0^' 1^ and 6"^ F. Through these points draw lines at right angles to

G' W, which intersect by lines drawn at right angles to 1 1 from

204

;iii:i:i- mktal work 233

siiuilar imnihers in \V ami X. Trace lines through thejx)iiit.s

tlius

uhtaiiuij. Then will N' ( )' U' S' he the pattern for the lower return

of the (a)), R K; while .1' M' L' K' will he the pattern for tl»e up|>er re-

turn. IM J.

In Fig. 31G is shown a perspective view of a gutter or eave-

trough at an exterior angle, for wliich an outside miter would he re-

t|uircd. It is iiiitnaterial what shape the gutter has, the nieth<«I of

nl)taiMing the pattern for the miter is the same. In Fig. 317 let 19

10 represent the section of the eave-trough with a l)ea<l or wire

edge at ah r; divide the wire edge, including the gutter and flange, into

an e<^|ual nund>er of spaces, as shown liy the small divisions d to 1 to 9

to 10. Draw any vertical line, as

A r.. ujM>n which place the stretch-

out of the gutter as .shown l)v sinn-ed »

lar letters and nund)ers on A B,

through which, at right angles to

.V H, draw lines, which intersect l)V

FiK. 31.s 1-iK. M'.).

•'IPS drawn pjtrallel to A B from similar points in the section. Trace

V line thntugh the points thus ohtained. Then will (' U K F be the

pattern for the outside angle shown in Fig. 31(1.

If a pattern is refpiired for an interior or inside angle, as is shown

in Fig. 31S, it is necessary only to extend the lines CI) and F K in the

pattern in Fig. 317, and ilraw any vertical line, a> 111. Tlienwill .1 I)

!•' II lie the pattern for the inside angle shown in Fig. 3 IS.

In Fig. 319 are .shown a plan and elevation of a moulding which

has more pn>jection on the fnuit than on the side. In other words, A B

represents the j)lanof a hriek pier, around which a ct)rnice is to l>e

constructed. The |>rnjcction of the given profile is itjual to C, the

profile in eh-vation heing .shown l»y ('. The projection of the fn»nt

in plan is also c«pml to C, «.s .shown hy C. The pntjecfion of the left

side of the cornice should he only as much as is shown l>yI) in plan.

This re«|uires a change of profile thn)Ugh I), as shown hy D'. I'o ob-

2UQ


tain this true profile and the various patterns, proceed as shown in

Fig. 320, in which A B C D represents the plan view of the wall, against

which, in its proper position, the profile E is placed and divided into

equal spaces, as shown by the figures 1 to 12. Through 1 2, par-

allel to C D, draw G F. Locate at pleasure the projection of the re-

turn mould, as B H, and draw H G parallel to B C, intersecting F Gat G. Draw the miter-line in plan, G C. From the various divisions

in the profile E, draw lines parallel to C D, intersecting the miter-line

C G as shown. From these intersections, erect vertical lines indefi-

nitely, as shown. Parallel to these lines erect the line K J, upon which

place a duplicate of the profile E, with the various divisions on same,

as shown by E^ Through these divisions draw horizontal lines in-

266

;'?'-

FRONT AND BEAK VIEWS OK HKSIDKNCK OK HENRY STEINBRENNER. BKl IKIDWKKAVENUE. CLEVELAND, OHIO

WnltonMiii \ S. Iiiirlili-r. Anhltr. !•<. < IrvrUnd. Ohio.

Ilrli'k l'<u<)l nil Kxl«rl<>r l« M<<';iu<iLiiiil lirlik. M.t<ln ni Akron. Ohio, linnts IVtrrml wiih•

llHl»orlftl" H«Hl TUn.

SHEErr METAL WoliK 235

tersec'tiiig tlie similarly miinl)eri'<l vertiial lines, as shown by tlie in-

tersectioivs 1 to 12'. Tiacr a line tliroiifjli these points, 'Hien will

F' be tlie true section or profile t)n II H in plan.

For the patternfor the return II (1 (' B in plan, extend the line

B A, as B M, upon which place the stretchout of the profile F', l>eing

careful to measure each space separately (as they are unwjual), as

shown by figures 1' to 12' on M B.

At right angles to this line ami through the figures, <lraw lines,

which intersect by lines drawn at right angles to II (j from similar

j)oints on C G. Trace a

line thn)Ugh the points

thus obtaine<l. T hen„ . TRUE PROFILE

will II' G» C B' be the THROUGH,

1" 7' IN

pattern for the return plan

mould.

The pattern for the

face mould G C D F is

f)btained by taking a

stretchout of the profile

E and placing it on thej<—

f^^'^'j

'^

"'.

FiR. .321. liK. .;-•.

vertical line P (), as shown l>ysimilar figures. thn)Ugh which, at

right angles to 1' ( ), draw lines intersecting similarly numberi^l lines

previously extended from (' G in j)lan.Trace- a lin«' through these

intersections. Then will 1 B'C 12 b«' the miter paltmi for the face

mould.

Ill I'ig. 'i2I is shown a pers|)ective view of a gore pie<-e .\ joineil

til a chann'cr. Thia presents a pniblein often arising in ornamental

ildT


PATTERNFOR GORE

sheet-metal work, the development of which is given in Fig. 322. Let

A B C D show the elevation of the corner on which a gore piece is re-

quired. H 7' E in plan is a section through C D, and E F G H is

a section through X I, all projected from the elevation as shown. The

profile 1 7 can be drawn at pleasure, and at once becomes the pattern

for the sides. Now divide the profile 1 7 into an equal number of

spaces as shown, from which drop vertical lines onto the side 7' Ein plan, as shown from 1' to 7'. From these points draw lines parallel

to F G, intersecting the opposite side and crossing the line 7' 1"

(which is drawn at right angles to F Gfrom T) at I" 2" 3" 4" 5'' 6". Draw anyline parallel to C D, as K J, upon which

place all the intersections contained on 7'

\" in plan, as shown by 1° to 7° on K J.

From these points erect perpendicular lines,

which intersect by lines drawn from simi-

larly numbered points in elevation parallel

to C D. Through the points thus obtained

trace a line. Then will 1^ to 7^ be the true

profile on 7' 1" in plan.

For the pattern for the gore, draw any vertical line, as A B in Fig

323, upon which place the stretchout of the profile F V in Fig. 322,

as shown by similar figures on A B in Fig. 323. At right angles to AB,

and through the figures, draw lines as shown. Now, measuring in

each instance from the line 7' \" in plan in Fig. 322, take

the various distances to points 1' to 7', and place them

in Fig. 323 on similarly numbered lines, measuring in

each instance from the line A B, thus locating the points Fig. 324.

shown. Trace a line through the points thus obtained. Then will

F G 7 be the pattern for the gore shown in plan in Fig. 322

by F G 7'.

In Fig. 324 is shown a face view of a six-pointed star, which often

arises in cornice work. No matter how many points the star has, the

principles which are explained for its development are applicable to

any size or shape. Triangulation is employed in this problem, as

shown in Fig. 325. First draw the half-outline of the star, as shown byA B C D E F G. Above and parallel to the line AG, draw JH of

similar length, as shown. Draw the section of the star onA G in plan,

Fig. 323.

268

<\]VVr MirrAL \V(jUK !n7

as shown by J K II. I'n>jeft K into plan a.s shown at I, and tlraw tlie

initer-lincs li I, (' I, I > 1, K I. an<l V I. As K II is the true lengtli on

1 < I. it is necessan,' that we find the true leimth on 1 1'. I'sinj; I F a^

nulius anil I as center, draw an are interseetinj; I it at a. From a

erect a line cutting J II in section at h.

Draw a line from h to K, whicii is the

true Itiigth on I F.

For the [lilt tern, proceed as

shown in Fij;. 32(5. Draw any line,

as K II, e<|ual in len<;th to K II in Fij^.

32o. Then, using K h as ratlins and

K in Fig. 32G as center, describe the

arc b h, which intersect at a and (i l»v

an arc (J (r struck fnini II as center

an(i with F G in plan in Fig. 32.") as

railius. Draw lines in Fig. 32(1 from

K to a to II to a to K, which will he the pattern for one of the jM)ints

of tlie star of which G are retjuired.

^Mien l)ending the points on the line UK, it is necessar\- to have a

stay or i)rofileso that we may know at what angle the hend siiould he

nuide. To obtain this.stay, erect fi-om the corner B in Fig. 325 a line

intersecting the base-line J II at c, fn>m which point, at right angles to

J K, draw c d. I'.sing c as center, and c d as radius, strike an arc inter-

secting J II at r. From c drop a vertical line meeting A () in j)lan at

(!'. .*>et off / W e<|ual to / H, and draw a line

from H to (/' to B', which is the truej)i\)file

after which the j)attern in Fig. 32() is to be

bent. If the stay in Fig. 32.') has been cor-

rectly develo|)ed, theiw/' B' or (/' B uuisti><|ual

! ii in Fig. 32ti on both sides.

In Fig. 327 is shown a finishe«l elevation

of u hippeil roof, on tlie four corners of which

a hip ridge .\ A butts against the uj)per base B

an<l r-uts olf on a vertical line at the bottom, as (' and C. To obtain

tiie tnie profile of this hip ridge, together with the top and lower cuts

nnci the |)attenis for the lower heads, proceed as .shown in Fig. 32X,

where the front elevation has l)een omitted, this not being ne<'essar\',

as only the part plan and diagonal elevation are letpiiretl. First draw

PATTERN FOR

^CORNER

FiK. :V2().

200


the part plan as shown by A B C D E F A, placing the hip or diagonal

line F C in a horizontal position; and make the distances between the

lines F A and C B and between F E and C D equal, because the roof

in this case has equal pitch all around. (The same principles, how-

ever, would be used if the roofs had unequal pitches.) Above

the plan, draw the line

G H. From the points

F and C in plan, erect

the lines F G and C I,

extending C I to C^ so

that I C will be the re-

quired height of the roof

above G I at the point

C in plan. Draw a line

-FRONT ELEVATION ^ ^^'^^^ ^ *» CS and from

C* draw a horizontal and

vertical line indefinitely,

as shown. Then will I G C^ be a true section on the line of the

roof on F C in plan.

The next step is to obtain a true section of th? angle of the roof at

right angles to the hip line G C* in elevation. This is done by drawingat right angles to F C in plan, any line, as a b, intersecting the lines

F A and F E as shown. Extend a b until it cuts the base-line G I in

elevation at c. From c, at right angles to G CS draw a line, as c d,

intersecting G C^ at d. Take the distance c d, and place it in plan on

the line F C, measuring from i to d'. Draw a line from a to d' to h,

which is the true angle desired. On this angle, construct the desired

shape of the hip ridge as shown by J, each half of which divide into

equal spaces, as shown by the figures 1 to 6 to 1. As the line G C^ rep-

resents the line of the roof, and as the point d' in plan in the true anglealso represents that line, then take a tracing of the profile J with the

various points of intersection on same, together with the true anglea d' b, and place it in the elevation as shown by J^ and a' d" b\ beingcareful to place the point d" on the line G CS making a' h' parallel to

G C^ From the various points of intersection in the profile J, drawlines parallel to F C, intersecting B C and A F at points from 1 to 6,

as shown. As both sides of the profile J are symmetrical, it is necessaryonly to draw lines through one-half.

270

SI I Hi: r MK'l'AL WOltK 2:j9

III similar iiiaiiiii-r, mi elevation, purallel to G C, draw lines*

thr.)ii;^'li till' various intersections in .1', wliieli intersectl)y lines drawn

at riL'lit antrles to F C inpli'.n

from similarly numbered j>oints on A F

w 214 3 6 34 125 5

PATTERN FOR LOWERHETAD

FiK. 32S.

and Br. "^Prace a line tliroii^di the points tlins ol)(aine«l. Then will

K I . lie (In- iiiitcr-line at the iMittotn, and M N the miter-line at the top.

I'or tlie |)atlern, draw any line, ils O P, at right an^^les to (» C,

271

240 SHEET ISIETAL ^WRK

upon which place the stretchout of J in plan or J' in elevation, as shown

by the figures 1 to 6 to 1 on O P; and through these numbered points,at right angles to O P, draw lines, which intersect by lines drawn at

right angles to G O from similar intersections in the lower miter-line

K L and upper miter-lineN M. Trace a line through the points thus

obtained. Then will R S T U be the desired pattern.In practice it is necessary only to obtain one miter-cut—either the

top or the bottom—and use the reverse for the opposite side. In other

words, U T is that part falling out of R S, the same as R S is that partwhich cuts away from U T. The upper miter-cut butts against B in

Fig. 327; while the lower cut requires a flat head, as shown at C. Toobtain this flat head, extend the line I G in Fig. 328, as I W, uponwhich place twice the amount of spaces contained on the line A F in

plan, as 6, 3— 5, 4, 1, 2, as shown by similar figures on either side of

6 on the line V W. From these divisions erect vertical lines, Avhich

intersect by lines drawn parallel to V W from similarly numl)ered

intersections in the miter-line

K L G. A line traced throughthe points thus obtained, as

shown by X Y Z, will be the

pattern for the heads.

^\Tiere a hip ridge is re-

quired to miter with the apronof a deck moulding, as shown

in Fig. 329, in which B repre-sents the apron of the deck cornice, A and A the hip ridges miteringat a and a, a slightly different process from that described in the

preceding problem is used. In this case the part elevation of the

mansard roof must first be drawn as shown in Fig. 330. Let A B CK represent the part elevation of the mansard, the section of the

deck moulding and apron being shown by D B E. Draw E X par-allel to B C. EX then represents the line of the roof. In its properposition, at right angles to B C, draw a half-section of the hip mould,as shown by F G, which is an exact reproduction of B E of the deckmould. Through the corners of the hip mould at Y and G, drawlines parallel to B C, which intersect by lines drawn parallel to B Afrom V, W, and E in the deck cornice. Draw the miter-line H I,

which completes the part elevation of the mansard.

Fig. 329.

272

SHEET METAL WORK ?A\

Befort- the patterns can l»r (»ljtaiiii*<l, a<k'velo|H.'<l

surface of tlie

inaiisanl must he ilrawn. 'I'hereforc, fn)m H (Fig. 330), tlrop a ver-

tical line, iLs B J, intersecting the line (' K at J. Now take the dis-

tance (tf B (', and [»la«eit on a vertical line in Fig. li^U, a.s shown hv

H ('. Thn)Ugh these two points draw the horizontal line.s B \ and

C K as shown. Take the jirojectionJ to (' in Fig. 330, and place it as

PART ELEVATIONOF

MANSARD ROOF

PART PLAN

TRUESECTIONON OP'R'

Via. :5:»n

shown fnini C to C in Fig. 331. an«l draw a line fn.ni (' to B. Theix

will A B (' K l)o the devclo|)ed surface of .\ B <" K in Fig. 3.30.

As l)oth the |)rofilesB \' W F, an<l F \ ( '. are similar, take a tracing

of cither, and |)lace it a,s shown l>y|) an.l 1 >'

respectively in Fig. XU.

1 )ividc l)ofh into the same mnnher of c«pial spaces, as sh«)wn. Bistvt

the angl. A I'. (

'

hy estahlishing a and /<. and, u.sing these a.H tx-nlers.

273


by describing arcs intersecting at c; then draw d B, which represents

the miter-hne. Through the points in D and D\ draw Unes parallel

to their respective moulds, as shown, intersecting the miter-line B d

and the base-line C C^

For the pattern for the hip, draw any line, as E F, at right angles

to B C, upon which place twice the stretchout of D, as shown by the

divisions 6 to 1 to 6 on EF. Through these divisions draw lines at

PATTERN FOR--.HIP RIDGE

I D'

hP•^ ^^^

5 6

DEVELOPEDSURFACE OFMANSARD ROOF

K

Fig. 331.

right angles to E F, intersecting similarly numbered lines drawn at

right angles to B C from the divisions on B (Z and C C^ Trace a line

through the points thus obtained. Then will G H J L be the pattern

for the hip ridge.

When bending this ridge in the machine, it is necessary to know

at what angle the line 1 in the pattern will be bent. A true section

must be obtained at right angles to the line of hip, for which proceed as

shown in Fig. 330. Directly in line with the elevation, construct a

part plan LM N O, through which, at an angle of 45 degrees (because

the angle L O N is a right angle), draw the hip line O M. Establish at

pleasure any point, as P^ on O M, from which erect the vertical line

into the elevation crossing the base-line C K at P and the ridge-line

C B at R. Parallel to O M in plan, draw O^ P^, equal to O PS as

shown. Extend P^ P^ as P^ R^ which make equal to PR in elevation.

274

;iii:i:r mktat. ^voRK 243

1 )r;iu ;i liii. iM-iii ll'toO'. 'I'lR-nO' It' 1*^ rt-prfseiiLsa tme.sertioiion

Ol" illj)laii. Thnnitfli any |>«)int,

sls a, atri;,'lit aii^'les to (JM, «Jraw

hv, cutting L O and ON at h ami c respettively. Kxteml b c until it

interset'ts O' 1" at d. Fntin d, at right angles to ()' K', ilraw tlie line

d e. With d as center, and dr as radius, draw the arc r «', intersecting

( )' P- at f', fn)m which point, at right angles to OM in plan, draw a

line intersecting OM at r". 1 )raw a lii'> fnjm b to i-" to c, whidi repre-

sents the true section of the hip after which the pattern shown in Fig.

'XM is fornietl.

The pattern for die deck mould D H in Fig. '.i'M) is ohtaintHJ in the

same way as tlie s(|uare miter shown in Fig. 277; while the pattern for

the apron D' in Fig. 331 is the same as the one-half patteni of tlie hip

riilge shown hv ;i II 1 0.

In Fig. 332 is .shown a front elevation of an eve-l)n)W dormer. In

tills view ABC represents the front view of the dormer, the arcs being

Fig. 332.

struck from the center points I), K. and F. .\ section taken on the

line II J in elevation is shown at the right; L M shows the roof of the

donner, indicated in the section hy X; while the louvers are shown in

elevation hy ( ) P and in section l>yHT.

Ill I'ig. 333 is .shown how to ol>taiM the various patterns for the

variousj)arts

of the doniicr. AI'ii repre.sents tlu' half-elevation of the

donner, and KF(1 a side view, of which FO is the line of the donner^

KF that of the n)of, and (IF the line of the pitched n)of against which

the donner is re(|uired to miter.

The fn)nt and side views lu-ing j)lace«lin dicir pii>pcr relative

positions, the first step is to obtain a true se<'tion at right angles io FF.

I'roc-ee<l as follows: Divide the curve .\ to ]\ int<» a number of etpial

spaces, as shown from I to [). \\ right angles to .\ (', and from the

figures oil A H, draw liiu-s intersecting K (i in .•*idc view as .shown.

87a


From these intersections, and parallel to EF, draw lines intersecting

the roof-line GF at P, 2^ 3^ etc. Parallel to EF, and from the point

ONE HALF TRUE 9J ' PROFILE ON LINE

E-H IN SIDEVIEW

9 7 6 5 4 3 2 1

ONE HALF PATTERNFOR SHAPE OF

OPENING IN ROOr

_9

V

Fig. 333.

G, draw any line indefinitely, as G H. At right angles to EF, and

from the point E, draw the line EH, intersecting lines previously drawn,

276

Slll.l/l METAL WORK 245

at 1', 2', ;>', III., a> îiiiu n. Now take a dupHcato of the line EH. with

tlif various iiitersectious tluTe«iii, ami placi- it on the center hnc ACextended as K.T. At ri<jht an<,des to KJ, and from the fifûrcs 1", 2^, 3*,

ete., draw hues, whieli intersei-t with those of simihir numbers drawn

at right angh's to CH, and from simihirly niunhered points on the cur\'e

A H. 'i'race a hue through tlie points of intersection thus obtained.

Then K L.M.I will be one-half the true|»rofile on the line K H in side

view, from which the stretchout will be obtained in the developmentof the pattern.

For the j)attern for the roof of the dormer, draw at right angles

to KF in sitle view the line X ( ), upon which place the stretchout of

one-half the tnie profile on the line KII as shown by the snuill figures

r. '2\ 3*, etc. Then, at right angles to X O, and through the figures,

draw lines, which intersect with those of similar numl)ers drawn at

right angles to EF from intersections on ECi and GF. Trace a line

through the ])oints thus obtained. Then will PKST represent one-

half the pattern for the roof.

To obtain the jiattern for the shape of the opening to be cut into

the ro(»f, transfer the line CIF, with the various intersections thereon,

to any vertical line, as UV, as shown

by the figures 1', 2«, 3', etc. In

.similar manner, transfer the line

C'H in fn)nt view, with the various

intersections on same, to the line

ZW, drawn at right angles to I'V,

as shown by the figures 1, 2, 3, etc.

At right angles to \'\', and fi-om

tile figures, draw lines, which in-

tersect with those of similar num-

bers drawn at right angles to Y'A.

Through these points, trace a line.

Then will LX^'Z l>r die half-pattern for the shape of the o|>ening

to be ctit into the main nnif.

I-'or the |)uttern for the ventilating slats or louvers, should thev

111-iii|uircd in the donner. |)ro(rrd as shown in Fig. 331. In thi.s

figure, A H ( is a repniduction of tlie inside opening shown in Fig. Xî.

Let 1, 2, 3, •}, .') in Fig. .331 represi-nl the srrtions of the louvers which

uill beplnci.*<l

in tliis opening. As the mellutds of obtaining the put-

HALP PATTERN FORLOUVRE *'4

7

27-J


terns for all louvers are alike, the pattern for louver No. 4 will illus-

trate the principles employed. Number the various bends of louver

No. 4 as shown by points 6, 7, 8, and 9. At right angles to A B, and

from these points, draw lines intersecting the curve A C as 6^ 7^ 4\ 8^

and 9^ On B A extended as E D, place the stretchout of louver No. 4

as shown by the figures on ED. Since the miter-line AC is a curve,

it will be necessary to introduce intermediate points between 7 and 8

of the profile, in order to obtain this curve in the pattern. In this

instance the point marked 4 has been added.

Now, at right angles to DE, and through the figures, draw lines,

which intersect with those of similar numbers, drawn parallel to ABfrom intersections 6' to 9*

on the curve AC. A line

traced through the points

thus obtained, as FKJH,will be the half-pattern

for louver No. 4. The

pattern for the face of

the dormer is prickedonto the metal direct

from the front view in

Fig. 333, in which A 8

B C is the half-pattern.

In laying out the

patterns for bay window^^§- "^'^•'^-

work, it often happensthat each side of the window has an unequal projection, as is shown

in Fig. 335, in which DEE shows an elevation of an octagonal base of

a bay window having unequal projections. All that part of the bayabove the line AB is obtained by the method shown in Fig. 290, while

the finish of the bay shown by ABC in Fig. 335 will be treated here.

In some cases the lower ball C is a half-spun ball. A^ B^ F^ is a true

section through A B. It will be noticed that the lines Ca, Cc, and Cd,drawn respectively at right angles to ab, be, and cd, are each of different

lengths, thereby maldng it necessary to obtain a true profile on each

of these lines, before the patterns can be obtained. This is clearly

explained in connection with Fig. 336, in which only a half-elevation

and plan are required as both sides are symmetrical. First draw the

278

SHEET METAL WollK 247

center line Ml, oi\ whicli ilraw the lialf-elevution of the hase of tlie

Imv, a-s shown hv (T>E. At ri;,'ht unfiles to All •Iraw the wall line

in plan, as FK; and in its proper position in relation to the line CD in

elevation, «lra\v the (lesire<l half-|>lan, as shown hy (lilM. From the

corners II ami I draw the iiiiter-lines IIF and IF us shown. .Vs DF

'

'I'L'

7 6 j^ 4 3 2 1

HALT PATTCRNR FOR 3

FiR. :vM\.

represents the^iven profile thronj,'h F(l in |)lan. tlien divi«le the profile

1)1'' into an eipial uumiIkt of spaces as shown l»y the lij^ures I to 1.?

Fmrn thesej)oiiits drop vertical lines intersecting; the initer-line Fll

in plan, a.s shown. From these intersections, parallel to III. tlraw

line's intersecting' the miter-lines IF. fn>m which points, parallel to 1.1.

draw lines intersecting' the «ciitcr line I'M Thnm^h the variiuis

points of intersection in I'l-, draw hori/onlid lines indelinitcly ri^'ht

and left as .shown.

270


If for any reason it is desired to show the elevation of the miter-

line FI in plan (it not being necessaiy in the development of the pat-

tern), then erect vertical lines from the various intersections on FI,

intersecting similar lines in elevation. To avoid a confusion in the

drawing, these lines have not been shown. Trace a line through

points thus obtained, as shown by D' 13, which is the desired miter-

line in elevation.

The next step is to obtain the true profile at right angles to HI

and IJ in plan. To obtain the true profile through No. 3 in plan, take

a tracing of J F, with the various intersections thereon, and place it on

a line drawn parallel to CD in elevation, as J^ F^ with the intersections

1 to 13, as shown. From these intersections, at right angles to J' F^erect lines intersecting similar lines drawn through the profile DE in

elevation. Trace a line through the points thus obtained, as shown

by 1' to 13', which represents the true profile for part 3 in plan. At

right angles to IH in plan, draw any line, as ML, and extend the va-

rious lines drawn parallel to IH until they intersectLM at points 1 to

13, as shown.

Take a tracing of LM, with the various points of intersection,

and place it on any horizontal line, as L^ MS as shown by the figures

1 to 13, from which, at right angles to L^ M\ erect vertical lines inter-

secting similarly numbered horizontal lines drawn through the profile

DE. Trace a line through the points thus obtained. Then will

1"— 13" be the true profile through No. 2 in plan at right angles to HI.

For the pattern for No. 1 in plan, extend the line FK, as NO, uponwhich place the stretchout of the profile DE as shown by the figures

1 to 13 on NO. At right angles to NO, and from the figures, draw

lines, which intersect with lines (partly shown) drawn parallel to FGfrom similar intersections on the miter-line FH. Trace a line throughthe points thus obtained; then will IP 13 be the pattern for part 1

in plan.

At right angles to H I, draw any line, as T U, upon which placethe stretchout of profile No. 2, being careful to measure each space

separately, as they are all unequal, as shown by the small figures 1" to

13" on TU. Through these figures, at right angles to TU, draw lines

as shown, which intersect by lines (not shown in the drawing) drawn

at right angles to I H from similar points on the miter-lines HF and FI.

280

SHKKT MK'IAL WOHK 249

'I'ruc-e a line thruu^li the points thus uhtuiiic*)!. Then will \' \V X l>e

the pattern for part 2 in plan.

F'or the half-pattern f»»r part 3 in j>lan, extend the center line A H

in plan as H K, ujK)n which place the stretchout of the true pmfile for

.'i, hein^ careful to measure each space separately, us shown by tlie

li^'iires r to 13' on BR. At ri^'ht an^'les to H K draw lines throuj^h

the fi<;ures. which intersect hy lines drawn at ri^'ht angles to .1 I fn»in

similar points of intersection on tlie miter-line V I. A line trace*!

tlironj,'h points thus obtaine<l, as T S 13', will he the half-pattern

for part 3.

DEVELOPMEINT OF BLANKS TOR CLR\LD MULLUlNuS

Our first attention will he <jiven to the methods of construction,

it hcinfj necessary that we know the methods of construction before

the blank can be laiil out. For examj)le, in Fi};. 337 is a part elevation

of a donner window, with a semicircular top whose profile ha.s an ogee,

fillet, and cove. If this job were undertaken by a finn who had no

circular moulding machine, as is the case in many of the smaller shops,

the mould would have to be made by hand. The metluul of c-onstruc-

tion in this case woulil then be as shown in Fig. 33S,

which shows an enlarged section through a b in Fig. a.

337. Thus the strips a, b, and r in Fig. 33S would be// X(-^

cut to the retiuired size, and would be nothing more / ^^KPthan straight strips of metal, while d d' wovild be an s^^angle, tlie lower side d' being notchetl with the shears

and turned to the re<juired circle. The face strips r,

/.and It would re|)resent arcs (»f circles to correspond

to their various diameters obtained from the full-size<l

elevaiiiiii. '!1ic>c face and sink strips would all be

sohh-rcd togetiicr, and fonn a succession of scpuire angles, as.shown. in

whit'h thcogfc, as shown bv (y,and the cove, as shown by m, wttuld lie

fitted. In obtaining the patterns for the blanks hammered by hand,

the averaged lines would be drawn as shown by h I for the ogee and

no for the cove. The method or principles of averaging these and

other moulds will be explained as we j»rocee«l.

In Fig. 330 is .shown the same mould as in th«" previous figure,

a dilTerent mt-thod of <-«»nstruction being employnl fn»m the«»ne nuide

bv hand and the onehannnered ui) bv nuichine. In nutchine work this

c^\

I'iK. Xi7.

281


mould can be hammered in one piece, 8 feet long or of the length of the

sheets in use, if such length is required, the machine taking in the full

Fig. 338. Fig. 339.

mould from A to B. The pattern for work of this kind is averaged

by drawing a line as shown by CD. This method will also be ex-

plained more fully as we proceed.

SHOP TOOLS EMPLOVED

When working any circular mould by hand, all that is requirerl

in the way of tools is various-sized raising and stretching hammers,

square stake, blow-horn stake, and mandrel including raising blocks

made of wood or lead. A first-rate knowledge must be employed

by the mechanic in the handling and working of these small tools. In

a thoroughly up-to-date shop will be found what are known as "curved

moulding" machines, which can be operated by foot or power, and

which have the advantage over hand operation of saving time and

labor, and also turning out first-class work, as all seams are avoided.

PRINCIPLES EMPLOYED FOR OBTAINING APPROXIMATEBLANKS FOR CURVED MOULDINGS HAMMERED BY HAND

The governing principles underlying all such operations are the

same as every sheet-metal worker uses in the laying out of the simple

patterns in flaring ware. In other words, one who understands how to

lay out the pattern for a frustum of a cone understands the principles

of developing the blanks for curved mouldings. The principles will

be described in detail in what follows.

Our first problem is that of obtaining a blank for a plain flare,

shown in Fig. 340. First draw the center line A B, and construct the

half-elevation of the mould, as C D E F. Extend D E until it inter-

282

PLAN OF RESIDENCE OF DR. FOLTZ. CHESTNUT HILL. I'HI L ADKLI'HI A. PA.

(imirtfxT. tVamon, Arohltoct, rbtlntlFltiliU. Pu

InlTliir WiiiMlwork UTrp«t<-<1 In Dulrh Hlylr. of !RrM>rii. nn'l l'il!i'»0 Wixnl In l.lvlinj Knoin itrnl SoiIIuvp II 1 utnl Kliiliti)'.) Ill rincpn nllh lju,',t!i

i ntliini'i 'hi- Imtih siyliv Kxiorlor \'li« Minwn

tniit III I

• Vlllti.•«

SllEK'l MI.IM. Wol'.K Ofol

st'cts the center line A B at ( J. Ai ri^ht angles to A H fnun any [xiint,

as II. draw 11 1I't^niA

to (

'

1), as shown. I'sing II as center, and with

II 1 as radius, descrihe the <|uarter-circle I 7, which is a section on

(,' l). Divide 1 7 into e(|ual spaces, as shown. Now usinj; (i as center,

with radii et|ual to (J E and < i D, describe the arcs 1) 7' and K E°.

Kn)in any point, as 1', draw the radial line 1' ( I, intersecting the inner

arc at K"^. Take a stretcluuit <tf the (piarter-section; place it as shown

Fir. 310.I'Hi. :u\.

from r to 7'; and ilraw a line fn)m7'iii (i, iiilcrseetin;,' the inner arc

lit \y. Then will 1-? I' 7' V° he the .|uartcr-pattern for the Hare 1) Kin elevation. If tlw pattern is re<|iiin'd in two halves, join (wo pieces;if rc<|nireil in one piece, join four

pii-crs.

In Fi;;. ."Ml is shown acnrvnl nioiihl whose pn)(ile contains a (^>ve.

To work this|)rolil<>.

the hiank innst Ik- stretclu-d with the stretching

hannner. W'r mm/ion this lurr so that tlir .slmlnil will piuj attrnhan

ht Ihi- riilr fnr (ihtniiiini/ imltrru.s fnr .itrrlrlud unniltit. First draw the

nnrcr line .\ H; als«» tin- lialf-elrvalion of the moulding, as (1) K F.

I >ivide tin- cove F, 1) into an «><|nal lunnhcr of spiuf.s, h.s shown fn)ni

2HM


HALF'ELEVATION .^ ,

a to e. Through the center of the cove c draw a hne parallel to e a,

extending it until it meets the center line A B at G, which is the center

point from which to strike the pattern. Take the stretchout of the

cove c e and c a, and place it as shown by c e' and c a'. \Mien stretch-

ing the flare a' e',c remains stationary, e' and a' being hammered to-

wards e and a respectively. Therefore, from c erect a vertical line

intersecting H 1, drawn at right angles to A B, at 1. Using H as center

and H 1 as radius, describe the arc 1 7, which divide into equal

spaces as shown. With G as center,

and radii equal to G a', Gc, and G e'

,

describe the arcs e" e", V 7', and a"

a". Draw a line from e" to G, inter-

secting the center and lower arcs at

1' and a". Starting from 1', lay off

the stretchout of the quarter-section as

shown from 1' to 7'. Through 7' draw

a line towards G, intersecting the in-

ner arc at a"; and, extending the line

upward, intersect the outer arc at e".

Then will a" e" e" a" be the quarter-

pattern for the cove E D in elevation.

If the quarter-round N O were re-

fjuired in place of the cove E D, then,

as this quarter-round would require to

be raised, the rule given in the former

Instruction Paper on Sheet Metal

Work would be applied to all cases of raised mouldings.

In Fig. 342 is shown a curved mould whose profile is an ogee. In

this case as in the preceding, draw the center line and half-elevation,

and divide the ogee into a number of equal parts, as shown from a to h.

Through the flaring portion of the ogee, as c e, draw a line, extending

it upward and downward until it intersects the center line A B at G.

Take the stretchouts from a to c and from c ioh and place them re-

spectively from c to a' and from e to h' on the line h' G. Then, in work-

ing the ogee, that portion of the flare from c to e remains stationarj^;

the part from e to h' will be stretched to form e h; while that part shown

from c to a' will be raised to form c a. From any point in the station-

ary flare, as d, erect a line meeting the line H 1, drawn at right

I

s

PATTCRN'

Fig. 342.

284

SlIKirr MKTAI. WOKK 253

angles to A H. at 1. l^iii^' II a> <«'iit»T ami II 1 a.-. ra<liu.s, ile-sc-rilje

till' (|iiarti*r->t'(tioii,and tlividt* saiiH- into

i-iiiial .s|iacfs,jts .shown.

With ( I II.S center anil with radii e<|ual to ( i «', ( J </, and (i h', descrilie

the ares a" a". I' 7', ami //" //". Knirn //"draw a line to G.

.•^tartiiij; at !', lay off the .stretchont of the sei-tion jls shown from 1' to

"'. Through 7' draw a

line to < i, as liefore de-

.serihed. Then will //" «"

n" It" he the (|tiarter-j)at-

ItTIl for tl le (u'ee Kl).

A|

In Fii;. ;{4;^ is shown

iiow the hlanks are di"-

velojHil when a h e a d

inonltlinj; is enij)loyed.

.\s l)ef«)re, first draw the ^\

center line A' R' and the

half-elevation .\ B C D.

.\s the head takesii|) j

of a circle, as shown hv

n c cj,

and as the pat-

tern for / (• will he the

same as for r c, then will

the patteni for r r only

he shown, which can also i

he use<l for //.

Hi.sect

(I < an<l '• (, ohtainin;: ^.L/

the points h mid f/_

which r c p If > f II t the

.stationary points in the

patter M ^. Take tin-

stH'tchoiits of l> to (/ ;ind

/' to '. and place them

HALF^CLEVATIOfjl ^

PATTERN

I

<* ^

KiK 3i:v

as shown from I, to d' and fnun t> to r'; also take the stretchonts

of ({ to <• and (/ to c, and jihice them fn>m d to r' nnd froni (/ to «•' on

lines drawn parallel respectively to m |Miints h and

'/. Kxteiid the lines »

'

c' and <•' «' until ihev intiTsii-t the cvnter

line .V H' at !•' and V respectively. I-'mm the points /» nnd (/

erei-t lines intersoctinj; the line (J 1. drawn at rijjht angles to A'

2AS


B', at 14 and 1 respectively. Using G as center, and with radii

eciual to G 14 and G 1, describe quarter-sections, as shown. Divide

both into equal parts, as shown from 1 to 7, and from 8 to 14. With

E as center, and with radii equal to E c', E d, and E e,describe the

arcs c" c", d' d', and e" e". From any point on one end, as e",

draw a radial line to E, intersecting the inner arcs atd' and c". Now

take the stretchout of the section from 1 to 7, and, starting at d', lay

off the stretchout as shown from 1' to 7'. Through 7' draw a line

towards E, intersecting the inner arc at c' and the outer one at e".

Then will c" e" e" c" be the quarter-pattern for that part of the

bead shown by c e, also for

ef,

in elevation. For the

pattern for that part shown

by a c, use F* as center; and

with radii equal to F a, F b,

Fig. 344. and F c', describe the arcs

a" a", h' b', and c" c". From any point

on the arc b' b',as 8', lay off the stretch-

out of the quarter-section 8 14, as

shown from 8' to 14'. Through these

two points draw lines towards F', in-

tersecting the inner arcs at a" o"; and

extend them until they intersect the

outer arc at c" and c'. Then will

c" a" a" c" be the desired pattern.

In Fig. 344 is shown an illustra-

tion of a round finial which contains

moulds, the principles of which have already l^een described in

the preceding problems. The ball A is made of either horizontal

or vertical sections. In Fig. 345 is shown how the moulds in a finial

of this kind are averaged. The method of obtaining the t;i:e length

of each pattern piece will be omitted, as this was thoroughly covered

in the preceding problems. First draw the center line A B, on either

side of which draw the section of the finial, as shown by C D E. The

blanks for the ball a will be obtained as explained in the Instruction

Paper on Sheet Metal Work. The mould b is averaged as shown by

the line ef, extending same until it intersects the center line at h, e /

representing the stretchout of the mould obtained, as explained in the

Fig. 345.

286

SIIKK/I' MK'IAI, WOUK 2.-..'

papff i>ri Slii'ft .Mi-i;il Wnrk. I siim h as ceiiUT, with // / ami // e as

railii, <le.srril)r tlie Maiik li^.

In tilt" next iiuHild, c c', a st'aiii is localnl in suine as shuwii hythe clotted hne. Thfii avera^'e <

'

Itythe line

/;', extending same until

it meets the center line at k: also averaj^e r' hy the line / m, extending

this also until the center line is intersecte«l at ti. Then // and / m

represent respectively the stretchouts of the mould c r', the blanks c°

anil c* being struck respectively from the centers k and n. The m«»uld

b' b" also has a seam, as shown hy the dotted line, the moulds being

averaged by the lines/>

n and .v /, which, if exteiule*!, intersect the

center line at r and //. These points are the centers, respectivelv, for

striking the blanks b° and 6*. I'he llaring pieces/ is struck from the

A 8

center jr, with radii e(|ual to .r w and .r r. thus ol)taining the blank d°.

By referring to the various rules given in previous pn»blems. the

true length of the blanks can be obtaineil.

The princi|)lcs used for blanks hanuncrcd bv hand can be applie<l

to almost any form that will arise, as, for example, in the case shown

in Fig. :i4(i. in which A and H represent circular leader heads; or in

that sh(»wn in Fig. .'MT. in which .\ and H show two stvles of balusters,

a and }> lin i)t)th) representing the s(|Mar«' to|)s and ba.ses. .\nother

example is that of a round litiial. as in Fig. .'Ms, A showing the IumhI

which slips over the apex of the roof. While thesj- forms «'an be

l)ouglit. yet in some cases where a special design is lii-ough.f out bv the

architc<t, it is nc-cessarv that thcv be made l>v li.ind. cspeciallv when

but one is nipiired.

'I'lu- last |tniblem on handwork is shown in Fig. ."MU that of

obtaining the blanks for the bottom of a circular bay. The cunitl

moulding \ will be hammerni bv hand or bv nuichine. as will Ik* ex-

2fiT

plained later on, while the bottom B is the problem before us. The

plan, it will be seen, is the arc of a circle; and, to obtain the various

blanks, proceed as shown in Fig. 350, in which A B C is the elevation

of the bottom of the bay, UK being a plan view on A C, showing the

Fig. 347.

curve struck from the center H. In this case the

front view of the bottom of the bay is given, and

must have the shape indicated by ABC taken on the

line I J in plan. It therefore becomes necessary' to

establish a true section on the center line S K in

plan, from which to obtain the radii for the blanks or

.^< )

Fig. 349. Fig. 348.

patterns. To obtain this true section, divide the curve A B into anynumber of equal parts, as shown from 1 to 6. From the points of

division, at right angles to A C, drop lines as shown, intersecting the

wall hne I J at points 1' to 6'. Then, using H as center, and radii

equal to H 6', H 5', H 4', H 3', and H 2', draw arcs crossing the

center line D E shown from 1" to 6". At any convenient point

288

SHRKT MKTAL WORK 2o7

op|)«»sitellif fn»nt elfvatioii ilraw any vcrlu-ul line, a.s T I . Ivxteml

tlif liiu's fniiii tlif spares in the profile A H until tiiey interseet

the \ertical line T \' as shown. Now, inea-surinj; in even- in.stunce

from the point S in plan, take the various distances to the nuin-

TRUC SECTION. ON 3-K

Kl

I 1'

\

E

Fig. 350.

hered points in plan ami place them upon lines of

similar nnmhers, meitsuring in every instance from

the line T l' in section. Thus take tlie distance

S K in |)Ian, and place it as .shown from the line

T r to K'jthen aj^ain, take the di.stance fn»m S to 2"

in plan, an«l j>lace it as shown from the line T \' to L'" on

line 2 in .section. Proceed in this manner until all the |M)ints

in the true .section have been ohtaineil. Trace a line as

shown, when 1" to (»" to V will he the true section uu tin-

line S K in plan.

It should l>c understood that the usual method for

making the hottom of hays n)und in plan is to diviile the profile nf

tlie niouldinj^ into such parts as can lu* licst rai.si*<l or stretchetl. As-

suming that this has heen done, take the distance fntm 1" in plan to

the center |>oint 11, and place it a.s shown from l" to L in section.

.From the|>oint L, draw a vt-rtical line I, M, ;us .shown. Kor the pat-

tern for the mould I" 2", average a line thmu^h the cMn-nu- points,

a.s shown, and cxtcuil the same until it meets I. M ;ii N. Then.

with N ;ls center, and with r.idii etpialto N 2" and N 1'. dcscril>e

M

880


the blank shown. The length of this blank is obtained by measur-

ing on the arc 1' 1" in plan, and placing this stretchout on the arc 1"

of the blank. The other blanks are obtained in precisely the same

manner. Thus P is the center for the blank 2" 3"; R, for the blank

3" 4"; O, for the blank 4" 5"; and M, for the blank 5" 6".

The moulds 1" 2", 2" 3", and 3" 4" will be raised; while

the blanks 4" 5" and 5" 6" will be stretched.

APPROXIMATE BLANKS FOR CURVED MOULDINGSHAMMERED BY MACHINE

The principles employed in averaging the profile for a mouldingto be rolled or hammered by machine do not difFer to any material

extent from those used in the case of mouldings hammered by hand.

Fig. 351 shows the general method of aver-

aging the profile of a moulding in determin-

ing the radius of the blank or pattern. It

will be seen that A B is drawn in such a

manner, so to speak, as to average the in-

equalities of the profile D C required to be

made. Thus distances a and b are equal, as

are the distances c and d, and e and/.

It is

very difficult to indicate definite rules to be

^B observed in drawing a line of this kind, or,

in other words, in averaging the profile.

Nothing short of actual experience and intimate knowledge of the

material in which the moulding is to be made, will enable the operator

Fig. 351.

SECTION

Fig. 352.

to decide correctly in all cases. There is, however, no danger of

making very grave errors in this respect, because the capacity of

the machines in use is such, that, were the pattern less advanta-

geously planned in this particular than it should be, still, by passingit through the dies or rolls an extra time or two, it would be broughtto the required shape.

290

SHEi-rr MKTAl. \v< 'i;l. J.-i9

III Via. •^'»- '•'* sliowij a part t-lfvalinii «jf a circular iixiuldilig as it

vvouM <»cciir id a segiiKMital peiiiincnt, wimlow cap, or oUicr structure

arising ill sluvt-inetal cornice work. H shows the cun'wl iiiouKling,

joining; two horizontal pieces A and ( ', th»' tniestH-tion of all the moulds

licin^ shown hy I>.

In this connection it may he proper to remark that in practice,

no miters are cut on the circular l)laiiks, the miter-cuts heinj: place*! on

ilie horizontal pieces, aii<l the circular mouldin<: trimmed after it has

iieen fonne<l up.

In Via. •i'hi is shown the method of ohtainin;; the blanks for

mouhlinirs cuned in elevation, no matter what their radius or pnjfile

B E

.nav lie. Kir>t draw the center line A U, and, with the desired lenter.

IS 15, descrilie the outer cur\e A. .\t ri«:ht angles to A H, in its pmper

position, ilraw a section of tin- profile as shownliy (1). Fnun the

various nienil>ei-s in this .section, project line> to the center line A H

a.s 1, 2, 3, and t ; and. iisin;,' H as center, descrilie the varituis arcs and

<-oniplete the elevation as shown l>y.\ H (' in Fi^. .T)2. only partly

diown in Fijj. •{')'i. In the manner liefore ile>cril»nl, averap* the

prolileC D liv the liner./, extciidiiij^' it until it intersects the lim- drawn

through thccent«'r H at ri^hl anj,'lcs to A M. at F. Then K is the center

from which to strike the |)allern. Centrally on the stHtion (' D. e.sial>-

lish f on the line r </. wlu-rc it intersects the mould, and take the

stretchout fnun * to (

'

and fiimi r to |), and phn-e it a.s shownn>r*jM««'-

tivelv from < to < and fn»m » to (/ on the line c </. Now, u.sinjj K h.s

•.MM

2t)0 SHEET METAL WORK

^:

ELEVATION

FIT PLAN

Fig. 354.

center, with radii equal to E (^, E e, and E c, describe the ares d' d",

e' e", and c' c" . Draw a line from c' to E, intersecting the middle and

inner arc at e' and d'. The arc e' e" then becomes the measuring line

to obtain the length of the pattern, the length

being measured on the arc 2 in elevation,

which corresponds to the point e in section.

In Fig. 354 is shown the elevation of a

moulding A curved in plan B, the arc being

struck from the given point a. This is apt to

occur ft^hen the moulding or cornice is placed

on a building whose corner is round. To ob-

tain the pattern when the moulding is curved

in plan, proceed as shown in Fig. 355. Draw

the section of the moulding, as A B, A C be-

ing the mould for which the pattern is desired.

C B represents a straight strip which is at-

tached to the mould after it is hammered or rolled to shape. In

practice the elevation is not required. At pleasure, below the sec-

tion, draw the horizontal line E D. From the extreme or outside

edge of the mould, as h,

drop a line intersecting the

horizontal line ED at E.

Knowing the radius of the

arc on h in section, place it

on the line E D, thus ob-

taining the point D. With

D as center, describe the

arc E F, intersecting a line

drawn at right angle to ED from D. Average a line

through the section, as GH, intersecting the line D F,

drawn vertical from the cen-

ter D, at J. Establish at

pleasure the stationary

point a, from which drop a line cutting E D at a'. Using D as

center, and with D a' as radius, describe the arc a' a", which is the

measuring line when laying out the pattern. Now take the stretch-

to A

Fig. 355.

292

111.1-. 1 MhlAL UOUK _'til

outs fruiii (J to A and fniiu a toe. aiirlpluc-t*

tlieiii oti tl'e averagwi

liiif fntiii a u> (i and fnnu a to II respectively. IJ^iiif?

•! «-"* feiiter,

with nulii extendiiij; to the varioas [M)int.s O. a. and II. ilesfrilx.' th»

ares (]\ a «'", ami II IP. Onthe urr <i' a'", tlie pattern is

inea-sured to eoiTe.sj)ond to the

arc a' a" in phm.In Fig. .'i.")(» i.s .shown a front

view of an oniainenta! huH'.s-eye

window, showing the circuhir

inouhi A H ( D, which in this

case we desire to hiy out in one

piece, so that, when hammered

or rolleti in the machine, it will

have the desire<l diameter. Tlic

same principles can he aj)plicd

to the up|)er mould K F, as were

used in connection witli Figs.—

352 an. I .{.-..i.l''«- 3^^-

To ohtain tlic l)laiik tor ilie hull '.^-cve winiiow .sht)wn in Fig. iiot?

proceed as .shown in Fig. 3o7. I>et A R (' 1) repre.sent the elevatio

of thel)uir.s-eye struck from the center F. Thnuigh F draw the lior

SECTION ELEVATION

FiK. 3.'>7.

/ontal and perpendicular lines shown. In il> pro|M'r position, draw n

H«'ction of the window lus shown li\ I'' <i. I'hrough the Uuf of the

mould, as II I. average the line II' I', extending it until it intersivLn

80S


the center line B D at J. Where the average Hne intersects the mould

at a, establish this as a stationary point ; and take the stretchouts from

a to I and from a to H, and lay them off on the line H* T from a to Pand a to H^ respectively. As 1

5 in elevation represents the

quarter-circle on the point a

in section, divide this quarter-

circle into equal spaces, as

shown. Now, with radii equalto J r, J a, and J H\ and with

J in Fig. 358 as center, de-

scribe the arcs H H, a a, and

I I. From any point, as H,on one side, draw a line to J,

intersecting the middle and in-

ner arcs at a and I. Take the stretchout of the quarter-circle from

1 to 5 in elevation in Fig. 357, and place it on the arc a a as shown

from 1 to 5. Step this off four times, as shown by 5', 5", and 5'".

From J draw a line through 5'", intersecting the inner and outer arcs

at I and H. Then will H a a H be the full pattern.

Fig. 358.

2fl4

O

•iHUp.

!3

;>

PLASTERING

TIh" siilijrctof plastiTiii;; in relation to iii;Mli'ni <lwr||iii}^ Is

iK'ie.s.sjirilv »livitl«'»l into two st-ftions. Tin- first treats of the plaster-

in"' of walls on tlie iiitrrior of the lions*-; tiie seeonil will lirielly ile-

st-rihe some of tlu- various ways of linisliinj^ in eenient plaster tlie

house exterior.

INTERIOR PI.ASTERING

The installation of interior plasterin>^ marks the division hetween

the eojnpletion of the roiu/li work on the residence, and the very

hef^imiitii; of the plaeinj; of thejiiii.sli

that is to follow.

The plastering; cannot he started until the walls and ceiliiifp

have been lathed, and the ceilinjjs must he furred hefore even the

lathinj; can he l>e<,Mni. When the huildini; is ready for lathinj;, all

of the roui^h studdinj;, framework, and partitions must he set in

])lace; and the piping; and wirin<; necessary in the |)hnnl)ini;, heating,

lifjhtinj;, etc.. of the «lwellin<;, nnist he installed and t«'sted hefore the

lathinj; or furrin<; can he started.

The apparent hreak in the proj^ress of hiiildinj; nece.s,sary to lath,

plaster, ami <lryout a house. nee<l not he altoi^ether time lost f«)r any

of the various trades, 'i'hose unahle to resume work until this inter-

nie«liarv pnwe.ss has heen complet«'d, can he secnrin<; their ne<r.>vsiiry

materials and fi.xtures and arran<;in<: tlitiii niuly for installation.

The carpenter can he t;«'ttinj; out his mill work and linish. Iw ready

to put in his window-.sash, set his standing; finish in place anxmd

diMirs and windows, lay the upper floors, etc., and complete tin*

remainder of his contract. The [)ainliT and pa|M'rer tlu-n commence

their work; the electrician^, |>luniliers, and healin'^ <-ontract«trs install

ilnir >cr% ic«- fixtures, and the tlwcllinj; is .s(M»n n-ady for o<cupalion.

The studs (tf a huildin^ are spaced sixt»-<'n inches apart on centi rs.

Si) that ea<h lath ree«'iv«'s four nailin^s. I''a<'h end of the lath n-sts

U|Min the leiitiT of a stud; and the two intermediate slu«ls proviiie

fiLstenin^s at spaces ctpiallv distant in its length. The «vilin^ art-

ao7

PLASTERING

customarily furred to provide lath nailings, four—and in better work,

five—nailings to the lath, with furrings seven-eighths of an inch thick

and one and one-quarter inches or more wide, running crosswise of the

floor joists.This furring is intended to level up the bottom of the

joists, and distributes the unequal result of their skrinkage or uneven

settlement from the weight above, thus preventing plaster cracks.

Before beginning lathing, the carpenter should see that each

partition, at its intersection with another wall, is started with a stud

nailed directly against the crossing studding. This makes it impos-

sible for the lather to run the ends of his laths in behind or over the

partitions—a careless practice that provides a very unstable internal

plaster angle. The carpenter also sets plaster furrings, three-quarters

of an inch thick, around all window and door openings and around the

walls at the height of the top of his base skirting, so as to mark the

points where the work of both plasterer and lather end, and to provide

nailings for the finish woodwork. It is essential for the carpenter to

place any necessary furring for cornices, door-caps, etc., before the

lathing is begun; also any other furring blocks that may be required

by the plumber to secure the setting of his fixtures or to support and

carry his pipes.

LATHING

Wood Laths. Wood laths are put up in bundles of 100 laths;

and are nailed upon the studdings of the wooflen frame, with a space

of one-(iuarter inch between them. This distance is sufficient to

allow for lath shrinkage or swelling, and still provide a firm clinch

for the plastering. If the space is much less than this, the plaster

clinch will be weakened. If much more, the laths may possibly sag

down on the ceilings with the extra weight of plaster. In no instance

should these spaces between laths exceed a width of three-eighths of

an inch.

The clinch, or key, of the plaster is formed by the mortar being

pressed through the spaces between the laths and then spreading out

back of the laths upon both sides of the crack, so forming a tie, or

clinch, that holds the mortar firmly and securely in place.

It occasionally becomes necessary to lath on very thin furrings

to cover over a heating pipe, a brick or iron support, or .some other

such exceptional instance of construction. In that case a wider space

298

V.WIJ..

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zwalOMK

PI.ASTl.lMNC

ln'twttii ilii- laili^ iii.i\ -^iM-n^tlini tlu'j)la.st»T t-lincli; «ir, iMttrr still,

a strip"f . m.iim!. ! metal may In- iisnl ovi-r <»r around siic-h ohstmo-

ti<)n>.

The l)fst wcmmIcii laths an- iiiatir <»f pine KPspnicc, aiul are only

[lartially sfusotu-d. Tlioy sliouM In- frc«' frnm sap, Imrk, ati<l doail

kiiiits. Hotli hark and knots urv likely to loosen fntni the snrround-

iiii^ \voo<l and so di-stroy the hold of the plaster; while the faee of the

plaster ii.' occasionally stained from pitchy knotholes, hark, orsjip.

All laths are now machine-sawn. The old-fashionedsplit lath has

not heen in the market for now more than fiftv vears.

If the laths are too dry, the wet niortar is likely to cause them to

warp and twist; and if it hardi-ns or sets before the laths Ix-come

saturated, their swelling; is likely to |)ro(luee parallel plaster cracks.

Better results can he ohtained hy i\s\u^ wet laths, when hotli mortar

and laths <lry out to<,'ether.

In spccifyinj; the nailin<j of wood laths, it is sometimes thou},'ht to

ensure I xtter work if two nailinj,'s are recpiired at each end of the lath,

cither upon the eeilinj; alone or upon lioth wall an«l ccilin<^. It is more

than doubtful if this re(|uiremcnt produces the desireil ri-sult, as two

nails in the lath eml arc likely to start a split, which may he incnnise*!

hy the pressure ncccssjiry in ap|)lyinfj the mortar, imtil the entire end

of the lath is partially or wholly loosened fn)m its sup|Mirt hefore the

|>lasterinj; is all Ujjon the wall. Larjjc lath nails, instead of tnakinj;

the work more secure, w«'aken it in the .same way. The common-sized inch-and-one-i'i;,'hth lon<; "three-peimy fine"— nails fasten the

laths M'curely, ••ven the ceiling nails rarely pulling out. AI»out five

pounds of nails will lie necessary (o each one thousmd laths.

The joints of laths are ordinarily hroken every ei>,'ht courses.

This means that not more than eij,'ht adjoining lath ends are naile<l

ii[M)n one stud or furriu;:, the next ei;;ht laths, in lM)th directions, U-inj;

carri«-«l hy, endinj^ u|H>n the next wall stud or ceilin;^ furrinj; to either

ri^'ht or left, thus alternatin/.,' the hreak an<l ohvialinjj the|K).ssihilitv

of an ext«-nd«'d crack iM-eurrinj,' at the line of lath jointure. Somelathers find a small hatidful of these laths more convenient to handle

than a larjjer hundle, in which case it is simpler and easi«T for themto hreak joints every six laths which is

e<|ually j^ikkI construction.

(Kcasioiuilly studdinj; is placed twelve inclu-s apart, and the lath

joints hroken for every oth«r lath. Such pnvautlon.s. however, urv

2on

PLASTERING

not necessary in the ordinary dwelling. They increase expense; and

the closer spacing of the studs, especially, provides more undesirable

weight to be carried by the house frame.

Wherever the wood studding of partitions comes up against the

brickwork of chimneys or a terra-cotta or brick wall, strips of expanded

rnetal or wire-mesh lath should be employed, extending seven or eight

inches over upon either side of such a joint; and, if such a joint occurs

in an internal angle, future cracking from a difference in settlement or

shrinkage may be prevented by cutting through each plaster coat,

when soft, with a sharp trowel.

Metal Lath. Of late years many varieties of metal lath have been

placed upon the market. The use of such lath is generally required

on boiler-room ceilings, and in other places exposed to strong artificial

heat. Many varieties of metal lath—including all those made of wire

—require supports at closer intervals than is provided by the studding,

nine inches being generally considered the best distance. This necessi-

tates either a closer spacing of studs than is otherv\'ise necessary or

desirable, or a series of furrings fastened to the wall studding.

There are some metal laths—generally those made on the expanded

principle—that are sufficiently stiff, in one direction, to allow of a spac-

ing of supports greater than nine inches; but, for ordinary wire cloth,

no wider distance should ever be allowed, unless the cloth is itself

artificially stiffened. All metal lath should be securely fastened by

staples, and stretched before nailing, to increase its stiffness as muchas possible.

In using metal lath, care should be taken to prevent plaster cracks

along the line of jointure. The use of metal lath also requires three

coats of plaster, in order to stiffen the lath sufficiently to resist the

pressure required to finish the last coat.

Lathing and plastering are generally estimated, and the various

materials are all figured, by the square yard. In small work, no open-

ings are deducted unless they exceed sixty square feet in area. In

figuring up plaster by quantity, when openings are allowed for, it is

sometimes customary to add half of the contents when measuringclosets ; while small triangular wall pieces are figured as though square,in order to make up for the extra amount of labor required in plaster-

ing such restricted or odd-sized surfaces.

The use of expanded metal or wire lath is frequently demanded

300

PLASTKUINO

by the hiiildiiij; laws of soim- cities, aiiid is always re<|uintl on a fire-

proof or lirst-elass i)uililiii^'.

Sevi-ral makes of pliislcr hoard are in tiie market and Ix-iri^

extensively advertised. Tliev eomc in eitrlit inch wide lM)ards or

lartre shwts of 32 hv 3(> inehes, and are nailetl <lireetlv uiK)n tin- wallo * » I

framinjj. One coat of [)laster— in tliree-coat work—may then Ix*

dispensed with. These hoards .save time, heinj; r.ipi<lly set in j)hiee

even hy unskilled carpenters, and the plaster it.self drys out mnch more

rapidly. They are, however, fre«|U<ntly the cau.se of cracks that

appear in the hnishcil plaster where the (^lixes of the lK)ards come

together—sometimes even after the wall has heen pa|)ered.

PLASTER MATHRIALS

Plaster is principally compo.sed of lime, sand, hair, and uHiter.

Lime is obtained in dilVerent .sections of the country from calcine<l

limestone, the carbonic acid and moisture contained in the stone

being tirivcn ofY by the burning process. The wliole theory of plaster-

ing is based upon the re<luction of limestone to limi-, and its chemical

recombination, when distributed upon the walls of a house, into

something approaching its original state. The slakimj of the lime

provides the moisture nece.s.sary for the process of crystallization that

prcMluces the sei of the mortar; while the .sole purpose of applying it

uj)on the wall in .several coats is to present that much more surface

to ab.sorb the carbonic acid—of which it was originally deprivetl in

burning— from the air. The thinner tin- coats and tlu' larger their

total ex|K).se<l surface, the greater the absorption of this strengthening

constituent. For this reason- and solely for this reason— is three-

coat plaster work to be considered as better than two.

Properly burnt lime slakes I'asily and completely, w hen water is

addnl, until it is convt-rted into a line dust, which, in its turn, is

moistened and turned into a paste iniijer action of (he waltr, which

bubbles and hi.sses with the heat generate<l by the process. This is

what is called the slakiiuj of lime. \'ery rich and pure lime the U-st

for plastering increases to about twice its original bulk by U-ing

•slaked, and is then almost pure white in color. Lime should always U'

us fresh as |M>ssible, and nnist be delivere«l in tightly seal«>»l barn-Is.

Can- should also Iw taken t(» u.scertain that it ha.s Urn burneil with

W(mh| and not with coal.

.101

6 PLASTERING

Sand is broken or rotten rock which has become decomposed

spontaneously or by the action of running water. That made by

running water, or from stones worn small by rolling over and over

upon the beach, is composed of particles so nearly round in contour

and so lacking in angularities of surface that they are not goodmaterial for mixing in any mortar where strength is a recjuisite or

necessity. The particles of rotten rock decomposed by exposureare better adapted to make good sand for mixing with mortar, their

shape being more irregular, with many sharp and angular corners.

Sand obtained from ledge stones contains the essential elements of

those stones, quartz, feldspar, and mica being present in granite

formations, and lava, obsidian, etc., in volcanic sand. The sand

coming from the softer stones is generally more thoroughly disinte-

grated, being frequently so rotten as to be entirely unsuitable for use

in plastering. In most parts of the country the principal supply of sand

now comes from the beds of ancient lakes or rivers, and is called pit

sand. True sand, no matter how fine, may always be distinguished

from dust by dropping it into a glass of water, as it will invariably sink

to the bottom without leaving any appreciable dirt upon the surface.

For plastering purposes, sharply angular sand is not absolutelyessential. Good river sand, the coarser the better, is obtained so easily,

and is so clean and free from dirt, clay, and earth stains, that it is most

generally employed for plaster.

The third necessary constituent is hair. The best hair upon the

market is cattle hair obtained from the tanneries. The hair should be

of good length; and, if too lumpy or clotted, it should be separated by

soaking in water the day before mixing it with the mortar, as this

method of separating the hair is less dusty and more healthful than

beating or whipping it dry to obtain the same result.

Occasionally brick dust is added to the mortar for coloring, whenit is likely that the mortar will set more rapidly

—especially if the dust

is mixed in shortly before using and is dry at the time of mixing. All

brick dust should be sifted through a fine sieve. Besides brick dust, a

variety of colorings for mortar are used—such as lampblack, ivory

black, powdered charcoal, Spanish brown, raw umber, burnt umber,red aniline, Venetian red, Indian red, vermilion, ultramarine blue,

indigo blue, chrome yellow, and, occasionally, pulverized clay.

Mineral colors should be preferred to earth colorings. The latter

302

PLASTKItING

weahi'ii the plaster, ami faile rupiilly. Xariously colored saiui.s

uliiii they ean Ik- obtained- make the In-st aiul most diirahle ma-

terials j)ossible for tiiitiii<; the iiiial plaster coat.

It is im|)ossil)h- to state arbitrary, set, hard-and-fasty)rf)portioii.s

for the iiiixin;^ of plasterinj^ for either exterior or interior work. The

dilVerent maki-s of lime and <;rades (»f sand, alone, vary sufficiently

to make any such statements exceedingly inadvisable; while tlu* pur-

jH)sc and conditions under which the plaster is to be usctl, fre<|uently

occasion considerable chanj^es in its prop<jrti(jns.

"Working" the IJme. The first process in the making; tif plaster

is the ulakiiifj of the lime. This consists, as aln-ady .sai«l, in simply

ritlucin^ tlie hanl, brittle hnnps of its orij^inal form to a sm(M)th [)aste

by mixiiii; it with water. It is of the utmost imj)ortance that the

limi- should be entirely and completely slaked, antl the jKiste smoothly

and evenly irorkcd, before ad<lini^ any of the other in;,'redients.

'I'he lime is slaked in a iitortur-hcd, a box «)f boards about 4 feet

wide and 7 feet lonj;, and a foot to ei<;hteen inches hi^h, .set in .some

convenient location with its bottom about level with the top of a second

1k)X placed at o!ie end, and about two feet lower in ^rade. Both

mortar and lime-slakini; beds should have tif,'htbottoms and stronj;

sides, well braced to resist the j)ressure that will come U|)on tluin

when thev are full. .\ (luantitv of .sand alreadv .scrt-ened shouM

also be near at hand. Toorly scn-ened sand lat«'r cau.ses extra tn)ul)le

and work. (Iravel in the mortar delays workmen whiU- plastcrintj

and floatinj^, and nnich ^'ood plaster material will Iw lost in hnrrii'dly

throw in<^ or pickinj; out these <^ravel stones in the rush of aj)plyin^ the

mortar on the wall.

The barrel lime is em|>tied into the upper l»ox, ami water is

|)oured on while a workman breaks up the lumps and works the mass

biick and forth in various directions with a hoe. Tin- thorouj;!! work-

inj; of the material at this stap" is m-cessary to jMisure its compl«-t«' slak-

ing. The tendencN of tln> can-less workman is to hoe back and forth

in the centtT of the beil without any repird as to whether he is stirring

up till- mortar that isdrtwn on tin* bottom bojinls.or whether th«M"orners

are drawn into the mixture and worked as «-venly as llu* remainder of

the Intx. If thepast«-

is not thon»U|,'hly and «'venly worketl to ani'^\\u\\

consislcn«'V throughout, if the water is not con«lucl«tl to every particle

of lime, or if the other in^'redienls are mixed in l>cfon- the paste 'm

303

PLASTERING

evenly prepared, the lime will be apt to blister and slake out unevenly,

causing trouble after it is upon the wall. If the corners, for instance,

are imperfectly mked, lumps of clear lime will afterward appear.

Many of these lumps will pass unnoticed under the hoe of the work-

man tempering the mortar, and will not be found until they are flat-

tened out under the wall trowel of the plasterer.

If too much water is used in slaking the lime—especially if a too

great amount is added at once—the pile is chilled and forms into lumps

that slake too tardily. If too little water is added, the lime is left so

dry (burns, as the plasterers call it) that many small particles entirely

fail to slake through lack of sufficient moisture. When too much

water drowns the lime in the first place, it becomes so thoroughly

chilled that a considerable portion of its strength is lost; and the proc-

ess of slaking is, by the very excess of water, much retarded. The

process is also slowed up if very cold water is added, although the

water soon becomes heated from the reaction of the lime. At the

start, just enough water should be put on to initiate the slaking process.

After this, as the slaking proceeds, more water should be added as

needed, taking care to keep the lime thoroughly moist at all times.

A very active and quick slaking lime should be covered with water

from the very beginning, to guard against the possibility of burning.

If the lime once burns, it will afterward be impossible, by any amount

of working, to get out all the fine lumps that are then caused. Rich

lime will afterwards work cool, is little likely to crack, and bears

troweling when being finished, without the surface peeling off, blister-

ing, or staining.

If lumps of unslaked lime escape through the screen when the

lime is run off, and get mixed into the mortar, it becomes very difficult

to eradicate them afterward. It is not possible for the plasterer to

get these lumps out of the mortar when working it on the wall; and

the results of their afterwards slaking out will continue to appear long

after the house is finished. If they occur in the first coat, at various

times after the work is completed—

frequently extending throughout

the entire first year—these lime lumps will suddenly bloiv or expand,

forcing out the surface plastering outside them and making a large

blister or lump, generally about an inch in diameter, which, if upon

the ceiling, almost invariably falls off. If this unslaked lime gets into

the final coat, much the same result occurs, although the particles

304

i'i.A.^ii':Ki::G

art- «il liti. >-Mii -iiiall»T in size. In.st(*a«l of U-in^ larj;«-, tlu* resulting

holes an- then eoniparativcly small, running; generally alnjut the size

of the head of aj)in,

and the entire surface of the plastering is fre-

i|Uently j)itte<l,the particles thnjwn olf ap|x'aring uUjut the room in

the sliapf of a white dust.

In the hruwn nuigh-coat, the s|M)ts of white, unslaknl linu- are

(|uite easy to see, as they are often the size of a Uaii orjx-a. How-

ever, in the final white coat, the.se.sjxjts, In-ing smaller and of the same

color as the rest of the mortar, do not show.

After it has once iHgim to warm up, the lime should U- worke<l

or s'irred thoroughly during the process of slaking, .so that, after the

action has heen completed, it will l)e (jf the consistency of a pastycream. After slaking, the lime should he run olf through a fine sieve

{No. 5 screen) put at the end of the slaking ho.x, into the ne.xt lower

compartment, or niortar-hed. The screen is inten<le<l to keep out any

lime lumps too large to slake before the mortar is u.sed, or anv flintv

settlement that may he found in the lime, and to allow only a pure and

thoroughly mixed hydrate to he admitti'd to the hed.

When drawing or ruiming off the lime, a large supplv of .sand

alreaily .screened shoidil he at hand to scatter in the bottom of the

mortar-bed and to u.se for .stopping leaks that may appear {is the Im)X

gradually fills. This .screened sand .should be sufficient in atnount

to complete the mortar mixture. .Vii ani|)le su|)|)ly of water, either

in barrels or in ho.si- piju-d from a hy<lrant, should also In- n'a«ly at

hand—to avoid anv i)ossibilitv of the lime burning.

For the pudi/ (tr finish coat, the paste shoulil be made even thiimer

befon- running oil', and may be of tin- consistency of milk. The sieve

through which it is stniined should also be finer, of alntut the mesh

of an ordinary flour or meal sen-en. The paste for this coat is often

obtaineil by rumiing off the lime a second lime, as by this means a

c(Mt|er working putty is seeun-d.

The leiigtli of lime that mortar for |ilaslering shouM !»<• mi\e«l

bi'fore bi'ing u.sed, is a mueh-«li.seu.s.sed ipiestion. It is generally

stated in architectund specifications, that "the mortar shouM U*

mixed ten ilays or two weeks before using." .\s a matter of fact, this

re<|Mirement is not always either wis«- (»r desind>l«'. It is true that, in

old English work, lime mortar wils left covered ovi-r with earth in

stand for long peritnlsof time, often six months to three years elapsing

no»

10 PLASTERING

before it was used. In this country, such slow-going methods are not

to be expected. While lime does gain in strength by standing in this

thin putty state before sand or other materials have been mixed with it,

yet three or four weeks, at the least, are necessary before the increase

becomes very apparent. It is also necessary that the paste should

remain moist, by being kept covered all the time. At the end of the

fourth month its strength will have increased about one-fifth, and

most of this gain has been made during that month. From then on

the gain continues, but gradually decreases in amount.

It is more economical for the plasterer to use a lime that has been

slaked for some weeks, as, when tempered down, it will work freely \

with the admixture of a much larger proportion of sand than is taken

up by lime mixed as soon as it can be readily worked. This extra

amount of sand does not add to the strength of the mortar; but, as it

causes the lime to cover a greater surface, it is a considerable economyfor the contractor, made, however, at the expense of the quality of his

work.

Lime mortar need be left standing only long enough for all its

particles to be thoroughly slaked, and, if properly mixed and wet

down in the first case, a great deal of time need not be required to

effect that result. This once secured, the quicker the mortar is mixed

and put upon the building, the better and stronger will be the plastering

that is obtained. It is further claimed that the accompanying loss of

limewater is also very harmful, as this water—from the properties

which it has already absorbed from the lime—is much better suited

for carrying on the process of mixing than newly added clean water.

Yet, if the lime has been long standing, it may be necessary to add clean

water to replace the water lost by evaporation or seepage, although

mortar mixed with clean water never becomes so hard as that mixed

with the water obtained in slaking the lime.

The sand and hair are next added, the hair being put in before

the mortar becomes too stiff to work readily. After the sand is mixed,

the mortar should not be left to stand for any length of time, as it

would become considerably set and a loss of strength would result.

If the mortar does become set in the bed, reworking woitld be necessarybefore it could be put upon the walls. The strength then lost bears

a direct relation to the length of time it has stood, and the solidity it

has attained, before this final working up.

306

PLASTEIUNG 11

In plastt'riii^mortar wlun- hair is rc«|uirf<l, a still furtliiT loss of

strt'Uf^tli wmilil H'sult, as tlii' hair would Ix- s<j rottwl or eaten by its

loii;j e.\|M)Siirt*to tlie action of the wet lime as to Ix- almost or (juite

worthless. The hair v-aiiiiot well Im- mi.\e<l evenly, except at the time

when the mortar is first run olT, while it is in a very thin paste. If.

after a liine-an«l-.siin(l nii.xtun' had lu'en stanilin<; for .some months, it

were attemptinl to ljrlii<^ it to a sudieiently lluid state to receive the

hair properly, hy wettinj; it down a .<econd time a consideraMe pn)[K)r-

tion- varvini^ from a (|uartrr u|)(o ..'most a halt- of its .strength would

Ik- sacrificed.

Bearinir these facts in mind—once certain that the lime is slaknl -

it would appear better that not more than a week .should elapse U-fore

the u.se of this mortar; and a less time than that is, under many circum-

stances, unilouhtedly desirahlc It is evitlent that no more lime-and-

sand mortar should Ik* mixed at one timi- than can he u.sed within a

few days at the most. The lenf,'th of time that mortar .should Ik*

allowed to stand, is deteniiined more or less Ity the dryness or moisture

of the atmo.sphere. The <lryer the atmosphere, the .shorter the time,

as the .setting of the mortar is, in part, a chemical result of the <lrying

out, or eva{)oration, of the iratrr of rrystallizotioti, as it is called.

It has already been .said that limes made in dill'erent parts of the

country vary extensively in their chemical composition and pntjMTties.

A knowledge of the chemical comj)osition of lime mortars and the

individual pecnliariti<'st)f the lime l(»cally used, is neces.sary In-fore

ap]»lving cir attempting to utilize the principles here .set forth. In

tiic eastern part of the I iiited ."^^tates, the limes friniuently contain from

a third to a half of carbonate of magnesia; and the mortar in which

sut-h limes an- employe<l .sets v«'ry readily.

To SIMM u|),the lime should be slaked as evenly and thoroughly

as jHKSsible.It should Ix' nm nil" froiu the slaking bed through a line

sieve into the Jnortar-lied It should lie there no longi-r than is ab.s«>-

lutely n«Te.s.san*; and if it could be possible to add the hair and siunl

while tin- original mixture is suflieiently moist to take up and W(»rk

tlif ••ntire amount of the latter material to be ailded. the residting

mixture would undoublrdlv !><• that niueh the stronger and mor»>

durable.

.Mixing the Mortar. The amount of sjind to Im- nnx«'«l in with

the lime pa.stc is a variable (piantity, »lepeiiding ti|Mtn the sand it.self,

307

12 PLASTERING

upon the quality and thickness of the lime paste, and also upon the

nature of the work for which the mortar is intended. With excep-

tionally rich limes, sand to the amount of about two times the bulk

of the lime—measuring the slaked lime in the form of a rather firm

paste—may be added. As will be seen, this is a most uncertain propor-

tion, for a great deal depends upon the firmness of the lime paste alone.

Allowing for variation in size of the lumps of lime and their closer or

looser packing together, it may perhaps be better to say that the sand

should bear a relation to the lime, before it is slaked, of from three to

four and one-half times its bulk.

The richer the lime and the finer the particles of sand, the more

of the latter should be employed, although the finer sand does not

make as hard or as good mortar as the coarser variety. If both are

clean and sharp, the finer and coarser varieties of sand may be mixed

together with good results. Most laborers are apt to stop adding sand,

merely because the mortar mixture becomes hard to work when the

paste becomes too thick. This is poor policy, inasmuch as the mix-

ture becomes much harder to work when the tempering is partly com-

pleted, a day or two later.

The fineness of the sand is an important factor. A rather coarse

as well as sharp sand is considered best, as the amount and capacity

of the voids left in such a mixture would be of such size as, without any

doubt, would provide space to contain lime sufficient to cement this

granular mass very firmly together. The close pressure and contact

of the sand particles would also lessen the possibility of settlement or

shrinkage, with accompanying map-cracks. The hair may be mixed

in either before the adding of the sand or when but a very small pro-

portion of the latter has been worked into the lime mixture. The hair

is generally mixed with the mortar by means of an iron rake. It should

be thoroughly mixed, and enough should be used to make it impossible

to find any small sections of the mortar in which the hair cannot be

seen. This will require from one and one-half to two bushels of hair

to a cask of lime.

If the mortar is to be used as a first coat on stone, brick, or similar

surfaces, it will carry more sand, and hair is not considered so essential,

a half-bushel to the barrel of lime being generally ample. If too little

sand is used, the plaster is liable to dry too quickly when setting, and,

after it is dry, will crumble very easily, showing up too white, or ashy

308

PLASTKKING 13

j^ray, in appcanincv. If Unt mudi .saml has \)cvu usf«l, the pla.sk*ring

is liabk' to fall off, and will cniinhli- when nil)lxtl iK-twci-n the fingers.

Mortar for a secoiul coat on lath may Ik? of uixjut tliLs same

consistency of niixtun". For the final coat (the putty c<jut or hard

finitli) hut very little sand is used. The hanler the finish, the less the

amount of sanil. For this coat, the .sand is mixed at the time when the

putty is run off. For hard finish, when marhle «lust, hrick ilust, or

anything of that sort is added, it is genenilly mi.\e<l together on the

mortar-l)oard immediately hefore applying. Stucco, or plaster of

Paris, is never mixed with putty until immi><liately U-fori' using, on

account. of its rapid .setting, whidi occurs in a few moments after

mixing, ^^^len once set before being aj)j)lied, it Ix-comes useless.

No more water than is nccessiiry .should be added, either in the mix-

ing of the mortar at first or in its sub.secjuent tempering, as over-much

wetting of the lime dej)rives it of a considerable projMjrtion of its

strength, and also retaRls the setting process by giving that much more

moisture that is necessar}' to be disposeil of by evaporation or crystalli-

zation.

A bushel of lime is standardizeil to weigh SO pounds; 2(H) |>ounds

is allowed to the barrel; a l)ushel contains about one and one-<juarter

cubic feet. A barrel of sand is .supposed to contain .'} cubic f<vt of

sand, and a bushel of .sand weighs about 120 pounds, and wet mortar

130 or 132 pf)unds. When hard, mortar is figured to weigh alniut 110

pfHinds to the cubic foot.

To summarize—one barrel of lime, 200 |M>unds, will take alK)ut

a cubic yard of .sand. In most localities a load of .s;ind is supixi.sitl to

contain twenty-seven cubic feet, or a cultie yard; but it is friHjuently

less than this, extending down to two-thirds of the amount. To the

barrel of lime should al.so be u.sed about two barrels of wat»Tand—as we

have seen— upwards of two bushels of hair for a first c«)at. IIair<N»nu\s

in pa|M'r bags wi-ighing generally something inuler eight pomids and

containing enough hair to In-at uj) into a nieasun-d bu.slu-l. This

amount of material, when the lime has Ik-imi slaknl and the whole

mixjHJ together, will amount to .!.') or 10 yanis (aUiul .'• barn-Is) of

mortar; and tin- amoimt shoid<l covc-r about 10 .s<juan' yards of

latlud an a. reipiiring about (KK) laths to surfaiH".

The final skim coat is mixe«l mughly to the following pn»|H»rlion.s:

A < a^k "f lime to a half-tub of wafer, which should fake up aUnit a

300

E

14 PLASTERING

barrel of the hard, clean sand used in the surface coat. Generally

the plasterer uses a larger barrel or hogshead for water, than the cask

in which the lime is delivered. Also, in some localities, the lime will

run somewhat more than 200 pounds to the barrel, Maine lime from

Rockland being supposed to average 220 pounds. Rockland lime is

considered in the East good lime for scratch and brown coats, but

many masons prefer Jacob's lime for the finish coat.

It should be remembered that the bulk of the completed mortar

mixture does not equal the total combined bulk of its various ingre-

dients, but is less than the aggregate bulk by about one-quarter.

PLASTERING

Interior plastering is now applied either in two or in three coat-

ings. Three coats are always necessary on metal or wire lath, the

first coat being required to stiffen the body of the material sufficiently

to allow thorough working of the remaining coats. Even upon wood

laths, three coats make a better job of plastering than two. Extra

strength and body are obtained by the addition of the extra coat, pro-

vided time be allowed to dry out each of the coats thoroughly before

the next coating is added. It has now, nevertheless, become the general

custom to employ but two coats on the less expensive grades of resi-

dence work.

The plaster mortar is applied to the walls with a hand trowel of

steel, about four and one-half inches wide by twelve inches long, havinga wooden handle that is parallel with the back of the blade. After the

mortar is put on and roughly smoothed out with the steel trowel,

the darby, a long wooden trowel, about four inches wide and three feet

in length, is taken by the workman and used—with a scouring motion—

to level the plaster surface and work it to an even thickness and uni-

form density. The flat part of the darby is generally of hard pine, a

half-inch or slightly more in thickness.

Three-Coat Work. The best interior plaster work always used

to be put on in three coats, and was worked to a final thickness of

about seven-eighths of an inch. Of the three coatings, the first is the

thickest, so that, when dry, it may be strong enough to resist the

pressure of working the coat or coats to follow. A large part of the

advantage of three-coat plastering is obtained by thoroughly dryingeach coat out before applying another, thus securing the added dens-

310

I'l.VSTKUlNG 15

ii\ ami .strt'ii^tli iiiadf jwissihlc \t\ futvin^ tlit* suhsitjut'nt c-oatinj^

tirinly and strtnijjly a<;aiii.st tlu* surfafe u|H)n wliicli it is Ijcin^ placetl.

|{iil»l)iii;,' or trowflin^' up tlir n)ii^h mortar U-fon* it finally dries and

M-ts, also niakfs it much mori' compact than isjH>.ssil»l«'

fn>m workingit at the time when it is first

aj)pli«-«|.

The first coat,calle<l the scrutcli cixtl, contains the grt^atest pro[)or-

tion of hair, that l»ein<; useful in strcnj^thenini,' the key or clinch of the

plaster hehind the edijes of the wixnlen laths, throu;^h the crevices

Itetwirn which it has In-en forced. Mefore this coat thon)U^hlv dries,

the surface is scratched (hence its name) with a tool di-signed for that

purj)ose. The surface of the secoiul coat also is sometimes scTatchetl

witli nails set into a wo<Mlen float or darhy like that used to ruh over

the surface, before adding the finish coat. When one coat is entirely

dried out before another is ap|)lied. this scratchintj is always necessjiry,

the scratches forming: a clinch or tie permittiu',' the sul)se<|uent coat

to unite the more firmly to the prece(lin<;.

The .second coat generally contains a larger pro[)ortion of sand

and much less hair than is nece.ssary in the first coai. The surface

of this second coat-—or brown coat, as it is calKnl— njust he l)n)U(:ht

up true and even, especially at all angles, and he |)lumh ujmhi the

walls. Hefore the finishing coat is applied, lumj)S must he removinl

and all other imju-rfi'ctions corrected, and the mortar must iR-come

sufficiently set to allow the entire surface to Ix- nihlud up with a float

or darhv and so mad *

compact and firm.

To .save time, the plasterer adopted the custom of putting his

sjrond coat on over the first while the hitter was still green. 1 he

comltinetl mass (practically one thick coat) was then darhied and

treated the same as in twu-<<ial work, over whicli about the onlv ad-

vantage of this method was in pntviding a rougluT .sand surface on

the second coat than was |)ossible when more hair (always necessiirv

in first coat) was included. ()therwise, substantially the .siiine ri'-

sults as are secured by thus working two coats ti»g«'ther are obtaineil

in the first <oat of ordinary two-i-out work, at a saving of lH)th Iai>«)r

anil time. While this method do<'s not furni.sh .so giMxl or .so |MTma-neiit a job of plast«'ring, it is m»Mlernly c«>nsi«leml as meeting the rt^-

(juireini-nts of three-<-oat work, when .sos[M'eifi«'«l.

The saving in this sort «»f thnnwoal plastering is made chiellv

by the plasterer, in the ex|H'nse of doing his work. The owner |>ays

.n 1

16 PLASTERING

more money than a two-coat job would cost him, and actually receives

substantially the same grade of work. The second coat, too, dries

more slowly when applied before the first coat is dry and hard, and

there is therefore not so much saving in time as is generally believed.

If three-coat work is attempted at all, it should be insisted that the

first coat be thoroughly dry before the second is added.

The final coat is generally composed of lime putty, with a small

proportion of white, clean sand, gauged with plaster of Paris. This

gives the whitest finished surface. If a color is considered desirable,

a colored sand may be used. All lath cracks or settlement cracks

occurring in the previous coats should be cut out and patched before

the last coat is applied. The final coat is about one-eighth of an inch

thick, and the surface is burnished with the steel trowel to an even and

straight surface, and worked sufficiently to free it from chip cracks or

other surface defects. The lime for the white finish mortar should be

run through a sieve of not less than ten meshes to the inch.

From thus combining the first two coats when green, the next step

naturally, in the development of methods of work, was to apply but

one coat, making it of increased thickness, and scratching it ready to

receive the finish skim or white coat, except when it was desirable to

finish the plaster with a rough surface, or to sand-scour it, as the last

process is sometimes called.

Rough Plaster Finish. If the mortar is to be finished with a sand

or rough finish, two coats are applied.

The second coat—which should be put on only after the first is

thoroughly dry—is substantially the same as the brown coat described

above, tlie rough finish being secured by working the surface of the

second coat, before it dries, with a soft-faced float and a mixture of sand

with some lime added. Sometimes the surface of the float is of carpet

or felt, sometimes of cork or other soft wood. Only so large a surface

as may be readily covered at one time, can be floated, darbied, etc.,

before it has time to set. In this case no hair whatsoever is put in the

second coat, as the hair destroys the evenness of the surface that is

obtained by the scouring action of the particles of sand rolling around

between the surface of the float and the face of the plaster. K long

float is generally used for scouring, and the surface is worked to an

even and true face, care being taken not to leave any marks from the

instrument itself.

312

PLASTERING 17

While it is m*iR'rally tlii' custoin to a<iy rou<;h-\v(»rkin<; the surface n{

the first coat. If oiie-<oat finish is employe*!, hair must Ik- use<l, and

the consistency of the coat must remain nuieh the same, whether it is

surface-finishe<l or not. In that case, however, it is not jxjssihle to

work the surface as true and as even as the surface of a second coat.

Two-Coat Work. Most j)!asterwork now consists of only two

coats.

The brown mortar employed for the first coat should he made of

fresh lime used as soon as it is stiti" enou^'h to he wijrked, with stronj;.

well-<listril)Ute<l cattle hair and coarse, clean sand. The first coat of

mortar must always be put <tn with sullicient pressure to forc-e the

plaster throuj,'li l)etween the laths, and so ensure a i,'oo<l clinch. The

face of this coat must be made as true and even as possible on surfaces

and angles, and plumb on the walls. After the first coat is sufficiently

set, it may be worked again with a float consisting of a piece of lianl

pine about the size of the trowel. Sometimes the faci- of this float is

covered with felt or other material to produce a rough textural treat-

ment on the plaster surface. The first coat should run a stnjiig five-

eighths inch in thickness, and should be thonnighly dried out.

It is generally inadvisable to attempt to trowel a two-coat job

verv smoothlv. If the attempt is made to float the first coat when it is

too thin or insufficiently .set, the instrument is likely to leave marks

on the wall, and the plastering is itself likely to crack. It is In-tter to

err on the side of caution, as, if the jilasterhas become .slightly t(H) dr^-.

it may easily be dampened by sprinkling water upon it with the plas-

terer's broad calcimine brush and following it inune«liat«'ly with the

float. The use of water in this way has accompanying a«lvautages

in that it tends to harden the j)lasteringand to prev»>nt the hairs

gathering along the edge of the float, when otln-rwise tlu-y would have

to l)o shaken off every few moments to jirevint their rolling under the

instnmient and Iwing pressed into the surface of the plaster in tuft.s

and rolls, in such a waiy as to .show through «ven the finish e»)at.

( are shoiiM l)e taken to see that each coat invariably is al).solutely

drvaiwl hanl Infore the addition of anotlur coat is atteni|»(«tl.( )ther-

wise the later e<»at will fall olT, in great<r or less part, ami it will Ik-

(piite itniHissibleever to obtain a giKnl surface finish; while, if it should

Tl.T

18 PLASTERING.

happen that the first coat is only partially dry when the second is

applied, it will be seriously injured by the pressure brought upon it

when floating. Its clinch to the lath is thus often partially or wholly

broken, sometimes the plaster falling entirely off, leaving the laths

exposed.

The finish second coat in two-coat work is the same as the final

skim coat in three-coat work.

The Finish Coat. The finish, skim, or white coat should never be

applied until the earlier coat or coats are thoroughly dry and hard, as

it is liable to crack if put on before—quite aside from the possible

danger of injuring the first-coat work by the pressure of troweling

before it is entirely dry and set. A simple putty coat should carry

more sand than when the finish is hardened by the addition of plaster.

If plaster is used, the mortar should always be gauged (that is, plaster

should be mixed with the putty) after it is placed on the mortar-board.

The usual process of gauging consists in making a hollow with the

trowel in the midst of the pile of lime putty lying upon the mortar-

board. This hollow is filled with water, and the plaster sprinkled

upon it, the whole then being mixed rapidly with the trowel and put

upon the wall immediately, before the plaster has time to set. The

proportion of lime and plaster, while variable, averages probably one-

fourth to one-fifth plaster.

The finish is skimmed in a very thin coating that is generallyless than one-eighth of an inch in thickness. It is immediatelytroweled several times, dampened with a wet brush, and thoroughlytroweled to smooth up the surface and prevent it from chipping or

cracking. The water prevents the steel trowel staining the surface,

but the plaster should not be too wet, as it will then blister or peel.

The whole surface of the finish coat, whether of putty or hard finish,

should finally be brushed over once or twice with a wet brush ; while, if

a polished (or buffed) surface is required, it may be gained by brushing—without dipping the brush into the water—until a glossy surface is

obtained.

Especial care should be taken, in the final coat, to finish all

joints smoothly and evenly so that the point of jointure will not be

apparent. The ceilings are completed first; then the upper part of

the wall; and lastly the bottom portions which can be reached fromthe floor and thus more carefully finished up to the joint.

314

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I'lii- plastcnr ;j»iit rally M-atFolds tlu' r<MHii witli lM»ani> al a

sulliiinitlii'ij,'lit

to riiahle liiin rasily U* n-atli (In- tt-iliiij^ overliftui

without raising his arms too hi;rh to work «'ach of tlu- coats i-wnlv.

Thr phistiT is applinl on thf up|)«T |)artof the walls fntin the siiine

sciitroldin^', ami the rrrnaiinlcr of tin- work is i-ompK'trd fn)m tin-

fl(M)r. If too much tiiiu- elapses in jo'uiiij; the coats at this jM)int,the

joint is likely to show—wljich is, of course, not serious unless the walls

are to lie lift Miitn-ated. <

)ccasionally two men workin;^ alonj:

tot^ether, one on the scalVoldin^ ami one on (he Hour, liiiish thv walls

at the same time.

If tlie oKl-fashiuneil wooden ani^le-heads are used, the plaster

should Ik* neatly cut out from each side, forming a small V-sunk an^le

that prevents the thin ed<;e ruiminj; up against the comer-lH'ail fn)m

breaking o\L As a matter of fact, the use of a metal (H)rn<'r-bead

makes a far truer, sharper, and straighter angle, and one that does not

afterward ti-ar or hreak the papering when it is put upon the wall.

Angles in the plaster are generally linishcd with a wcmmIcii paddle.

As th«' hair is ii.sed principally to insure a clinch hack (tf the lath,

if plaster is applied on a stone or hrick wall, a .scratch coat is .seldom

neces.sary; and the coat of l)ro\\;n mortir is very often u.sed without

hair and of nhout the c-ompositioii of hrick ina.son's mortar. If a

.s<'nitch coat is u.sed under these conditions, it is i;enerallv mixinl with

more .sand and h-ss hair than when put ujmmi laths.

For a finish wh«'re plaster mouldings are to Im- used, or when for

any pur|)o,s«'an mujsually stniight, level, and pluinl) surface of plaster

is rn|uired, three-n-oal work, put on in the old-fashione<l manner,

shoidd lie demanded. This is necessarv in order to j/et a surfacv

sulliciently level and true to run plaster mouldings evenlv, and to

nvfiid the ine<|iialities that are almost certain to occur in all twiH-coat

plastering.

The .s<'cond and third coats allow opportunities to ohtain a stniight

ami level plaster surface. Individual s|Mits ar»' hrought up to an even

.surface, the plaster then Iwing added and carefnilv w(trk«>«l U'tween

and amongst them, hringing it all to the .saim- faci-l»y m«'ans of the

straight edge. ()cc;isionally it liap|M'ns that the nuigh i-oaf is so

tmeven that .some filling in is ahsolulely necessary to make the wall

sudieienlly even to receive the last c<tat. In that ease, a miMiin- of

half plaster and half jtiitty may U* u.seil in leveling up the rt>ugh work.

ain

20 PLASTERING

If no finish coat is to be put on, the surface should be troweled smoothly

as the mortar is applied, care being taken to lea-^'e no marks, hollows,

or uneven places; but if the wall is to be finished or frescoed, it should

be left with a floated surface.

Patent Plasters. Patent plasters, such as adamant, etc., are not

often employed for private dwellings, being chiefly suitable for mer-

cantile purposes. The patent plaster has certain advantages that are

self-evident—such as quick drying and hardening. Its surface

hardens more quickly and resists abrasure longer than the ordinary

lime plastering However, a break once occurring, the extreme stiff-

ness of the mixture makes it liable to extend further and to be of a

more serious nature than if the softer, more flexible lime plaster cov-

ering had been injured in the same manner.

The extra stiffness of most patent plasters is caused by the cement

that generally forms an important part of their composition. These

plasters are sold ready for use, requiring merely the addition of a

sufficient amount of water. They are therefore especially adaptedfor use by the inexperienced, and are valuable for executing small

pieces of work, as they do not present the liabilities to failure, or loss

of time and delay, occasioned by mixing up batches of lime mortar.

Back Plastering. Occasionally a wood-framed house is back-

flastered for warmth. This process consists in nailing a strip of

seven-eighths inch furring against the inside of the boarding on each

side of the studs. The space between the studding is then lathed

(of necessity a slow and bothersome job) and plastered one roughcoat of hair mortar, which should be allowed to dry before any lathing

is placed over it on the inside face of the studding. As a matter of

practice, the efficiency of back plaster is much injured by the fact

that the studding, m seasoning after the plaster is set, is likely to

shrink away from the plaster, leaving a narrow perpendicular crack

on each side of the stud, which permits of the passage of cold air.

Plaster Cracks. Cracks in plaster occur from several causes.

If the distance between the ends of the laths, where they join on the

studding or furring, is too great, the larger amount of plaster in that

place, when drying out, may cause a short crack. Any such spaces

should, however, be. filled by the lather before plastering is begun.

Sometimes, too, especially in the first coats, cracks are caused by the

shrinkage or expansion of the wooden laths after the mortar has

316

I'l.ASrKRlN'G

wholly or partially st-t. I'lurr.siilt is a sfrics of narrow cracks paralU'l

to racli otIuT ami tlif wiiltli of tlit- laths apart, l^ath crackn art- or<ii-

riarily fillrd in an<l coveriHl n|) l»y later coat.s, and .s«» do not «)ftfnup|H'ar

in the iinishnlpla.sti-rin;,'. Tlii-y may, tiK), he workcti out when float-

ing ii|>the coat before it finally sets. If wide or deep, however, they

slionld he cut out to a widtli of an iu'-h or so, and fille<l in with new

mortar hefore adding the last coat.

Cracks of a like appearance are sometimes cause*! hy the rough

mortar heing too rich, orl»y draughts of air fn)m o|)en d(M)rs or win-

dows drying out portions of the plastering too <|uickly. The too

raj)i(l drying of plaster with stoves or salamanders, oft«'n prcHJuces a

like result fn)m similar causes. An experienced plasterer should Im?

uhle to determine the rcsponsiblecau.se and take measures acconlinglv,

using more siind if the mortar is too ridi, .screening openings to prevent

draughts, and using less fire in his drying stoves. In green work,

damage already done may he rej)aireil hy refloating again before the

work becomes too dry, softening the mortar with water if necessim*.

Tracks sometimes wcur in the angles at the ceiling or corners of

the room. When in this location, they may be cau.se<l by the shrinkiige

or settlement of the partition or floor. In the j)erpendi<ular angli-s,

esj)ecially, they may extend only to the depth of the finishing ix)ats.

In that ca.st,the causes are likely to be either too thick jilaster, insuffi-

cient troweling, or an insufficient amount of|)laster in the piugetl

coat—cati.ses whicli are easily n-miHlied in the remainder of the work.

Cnicks running diagonally across a jtartition, or radiating fnmi

tlie comers of doors and window openings, are cau.sed by the unetjual

settlrment or shrinkage of llie buiMing. They fre<|Uently <H-cur at a

perp<ridicular angle wliere a wood partition is brought up apiinst a

briek wall, r)r at the ceiling line where a woo<len floor comes up agiiin.st

a brick sup]Ktrting wall.

f racks inrur in the final finish when the putty is not gjiup"*!

enough or not troweled or brushed enough, wlu-n it is|>ut on t«>o thick,

and when tiwi little sand has be«'n used. 'I'he.se cnuks an- calletl

rliipjiid rrtuks. I'laster. wlu-n apparently jK'rfect and without cracks,

will sometimes crumble, <'ither fn)m tiM» nipid ilr%'ing or from the us*-

f>f t(K) much .S4ind. Hither too much or t»M) little .sand materially

injun-.s the strength of mortar.

817

22 PLASTERING

If unclean sand, dirt, or clay has become mixed with the mortar,

it not only weakens the lime but prevents its adhesion to the sand

particles, so that no real set of the mortar ever occurs. Of course,

at all times, poor materials—sand, lime, or hair—may be responsible

for defects in plastering. Plaster occasionally falls off even when

apparently hard and good, if the laths are too near together, if there

is insufficient hair, if the mortar is too rich or too sandy, or if it had not

been pressed against the laths with sufficient force when being applied;

or it may become loosened by the springing of the laths under the

pressure of floating it too hard. On brickwork the mortar requires

considerable more sand than for application on laths.

Lime must have time to set before it dries out. Therefore, to

last well, it should dry slowly. A stiffer working mortar makes better

and harder plaster than thin or wet material, provided, of course, it

is thin enough to clinch well to the lath in first-coat work, or to adhere

to brick and dry scratched surfaces, and to spread evenly, in second-

coat work. Stiffer mortar can safely be applied upon wet mortar

than on dry; and wide-spaced lathing will take stiffer mortar than

close-laid laths. When two coats of mortar have been put on, and

the last coat falls from the first, it is generally because the first coat

was not wholly dry when the second was applied. The coats must

either be entirely dry or quite green to be successfully combined.

If possible, it is better to have the workman use makes of materials,

especially lime, having those properties with which he is acquainted.Attention has already been called to the fact that different makes of

hme vary considerably in their chemical composition. It is not even

certain that lime of the same make will always run even in production,

year after year. Of course, lime that has been slaked by exposureto air or water while in the barrel, and before it is used, is worthless.

As this occasionally happens, it is well to be watchful and see that

such bad material is never added to the plaster bed.

As a final warning, be certain that the last coat of plaster has

dried out hard and strong before any wood finish is installed, as other-

wise the wood will absorb the moisture from the plaster, causing it to

swell and therefore opening cracks that are never likely afterward

to be altogether closed. All wood finish should also be kept out of the

house while plastering is going on, as it will absorb moisture from the

air around it. The reason that sash are not ordinarily set until after

318

ri.ASTKUIN(i 23

th«'j)la.stt'rin<j

is ruiislittl, is luraiis*'tli«*y

altsorl) .si» imu-li nf the

moisturt' as to t-aiisr the sasli lo >\v«'|| inj)la<<-.

It is p-MHTally c-on-

sidt-rnl prrfi-ral)!*'tit till tlu- \viiitii)w

()|M-iiiii^sor ihwirs with scrvenij

of c-ottoii cloth, as tliis prevfiits <lir«ft draughts anil still allows of a

cirnilation of air that ilrics phtstrrin^ much nion-ra|)iilly than artificial

lit-at, «»r than it would dry if these opcninfrs wen- cIosihI l»y .s<j|id do<»rs

and t'la/cd sash. In vcrv hatl weather the scn-en cif cotton inav Ik*

sli;,'htly stRMiffthenetl, if nect'ssary, l)y the a|)|)lieation of a coat «if white-

wasiion the inner side. Contrary to wliat niij^ht !><• suj>[>osed, thedrjth

window-screen is almost as goo«l a |)n»tection a^âinst external cold

and fn)st as is the tjlazed window, althoiij^h the current of air passinj^

thnni;^h the cloth meshes of these screens into and out of the house,

causes a slif^ht loss of heat, addint; somewhat to the exjH-nsj* for fuel

re<|uire<l to dry out a j)lastered l>uildin<;. In ô«h1 dr^'iiji; weather,

these screens shouM he taken out and left out durinj; the <lay. hut

should he replaced at nij^ht or in dani|) weather, when the |)laster

otherwise is likely to reabsorb moisture from the air ami so delay the

time of its final drying out.

If avoidable, the artificial dryiu'j of plaster by salamanders should

not be employiil; natural dryiii}; by sun and air is. und<-r all cin-um-

stances, preferable. The salaman<ler not only dries the room in which

it is jilaced,inci (|uickly

—especially the ( riling al>ove—but fills the air

and the j)laster itself with jjas fumes, and, by steamini;, is fre<|Uently

the cause of the rottin<; of plaster or hair, thus reducing its vitalitv

and life. Heating a house to dry out the plaster by means of the

regularly installed heating plant, is prefcral)le to the use of salamanders,

the chief objection iti this ca.se being occasioned by the unduly nipid

drying-out of wall j)laster back of or above registers and nidiators.

The situation ishelp«'<l

if the radiator is set out from the wall and sonu'

scTcen is |)laced U-tween it and the plasicr. .\ screen may also Ik*

einployi-il against the wall over a hot-air n-gister; but tlH-n* is no

means of protecting the plaster on either side of a partition thnuigh

which a hot-air or steam pi|>e passes. .*ûch plaster is Unnid lo Ik*

.s«'verelv strained by In-ing dried loo (|uickly.

If jdaster i.s fro/en when wel, it is likely to loosen up and injure

the whole iiiavs so that il may eventually fall olT. The elTecIs of

fre<'/ing are less troublesome if the wall is fn»/.i-n afl«'r it is drini and

has (Mice set. If only slightly frosleil, and ihawetl inuneilialely and

Mti

24 PLASTERING

floated again, it may often be saved, the effect in that case being not

much different from what it would be if the wall had been surface-

moistened and refloated.

Plaster Moulding. Plaster mouldings upon ceilings and walls

are less frequently employed now than a few years ago, when, espe-

cially at the intersection of wall and ceiling, a heavy cornice of plaster

was the common method of finish. Nowadays a cornice of wood is

more commonly used.

Briefly described, the running of a moulded plaster cornice is

as follows: Two parallel strips, or screeds, are run on the ceiling and

the side wall, with their nearer edges evenly straightened. These edges

are then fitted to the mould—a piece of metal cut out to a reversed

section of the cornice outline. The mould is run along the strips

fastened to the wall for guiding it, the lower edge being cut out and

fitted to run upon them.

The plaster necessary to fill up the mouldings of the cornice maybe tied back to the wall and ceiling by rows of nails driven so as to

stand at about the location of its greatest thickness; while a strip of

metal lath, filling in the angle upon projecting furrings, will offer the

best possible clinch, and will help to reduce the thickness of the

plaster and render its drying and shrinkage more equable and its sur-

face less likely to crack.

When all is ready, enough putty and plaster are gauged in about

equal parts to run the cornice down the length of one side of the room.

The moulding form is then rested upon the supporting and guiding

strip against the wall, and drawn along from right to left, pressed

against the mass of mortar which is thrown into the angle just ahead

of it by the trowel, the space immediately in front of the moulded strip

being kept sufficiently full of plaster mortar to fill out the moulding

entirely at all times. When the length is completed, or the gaugedmaterial is used up, the mould is moved back and forth along the

length of cornice that has just been run, scraping away all the plaster

except that included within the outline of the mould.

Where hollows occur, the gauged material scraped off by the

mould should at once be thrown on again at these places, so thai they

may be immediately filled and brought up to the right section outline

by again running the mould over these portions. The gauged puttywill set in a few moments, and each side of the room or section of the

320

PLASTKlUNt;

lUDiiltliii^ must \h' mil iiiwi cuniph-tt'*! or fillt**! out very rapidly. Tlif

ciiniers at tht- aii^K'S of tht- nunu may In- fillnl in l>y hand, or a section

of tin- mould may Ik* separately luii upon the fU>or, sawn in a mitre

Im)X, niitrnl and fitted in j)laee U|>on the wall, the joint Ix'tween the

east and run nioidtlin;; heinj; then earefully patihe<l and evened off.

The extra amount of plaster included in the thickness of extreme

pntjectin;^ mouldinj^s is the cause of occasional surface craekinj^; while

other cracks are oc-casionetl hy the settlement, shrinkage, and move-

ment of the house frame. Vnr these and other n-asons, it is now gen-

erally considereil that a woo<len cornice, chspite its defects of shrink-

age, is better suited than plaster to this purjxj.se.

Finally, the mouldinj; may he sprinkle<l with the hrush and the

mould may he run over it several times more, endinj; hy finishing

with a hrush so as to give the moulding a gloss just as on the wall

plastering. The same pnK-ess is repeated for dilferent kimls of plas-

ter moulding, merely varying the metluKl to provide for the ditferent

conditions .set hy circumstances, a circular niouliling aroimd the

lighting outlet in the middle of the nxtin, for inslance, heing swungfrom a peg driven into the center of the gas j)ipe or outlet Ih>x. ( )ther

kinds of plaster mouldings are run hy unimportant variations of the

proces.ses dcscrilKnl.

Cast ornaments are made .separately in moulds, into which the

plaster is pnired. Most of these sepanite moulds are made ofjilaster

hardened with glue or shellac, or surfaced with heeswax, and are

gem-rally oile<l hi'fore heing usetl. IMaster ornaments are fastened in

place with fresh plaster or glue; (K-casionally a few .screws are u.se«l,

in which case the heads .should Ik' countersunk ami covered in with

pla.ster .so as not to show.

liXTI:RI()lv> PLASTIiRINO

.Mlhonyh exterior plaster surfacing for dwellings has Keen in use

in l'hiro|M'for many years, it has hut reii-ntly met with fav«ir in this

COlintrv. Ill llalv, plaster, or stucco, a|)plied in large, imhroken

e\|>aiise> upon a >loiie or hrick huilding, has long U-en a favorite

niethiMl of construction, l-'reipu-ntly, Iik>. this|>la.s|er .surface is

stainetl or col(»rrd and workedii|>

iiilmlith-n'nt «'«'signs. In l\ngland.

France, and < iermany, plaster has Ix-en more fntpiently usetl in con-

321

26 PLASTERING

nection with a half-timbered frame, although these countries also

contain instances of its use in large, unbroken, simple surfaces.

In modern American work, it is not often that a brick wall is

covered with plaster, as the aesthetic possibilities in the use of roughhard-burnt brickwork have now long been recognized; and when

this—the cheapest brick-building material—is employed upon a

dwelling, it is itself utilized for the exterior surface and to obtain the

exterior effect of the structure.

Plaster has been used in this country in imitation timbered houses

for some years ;but recently its employment in large, simple surfaces,

unbroken by the cross-barring strips of dark wood, has become popular—a treatment much more appropriate to this country. We also

possess some examples of brick and stone houses, two hundred years

old or thereabouts, that were covered and surfaced with white plaster-

ing; but in the most recent of American plastered dwellings, this effect

has been simulated by applying the plaster to a wooden frame lathed

with a fine-meshed wire cloth.

In any plastered building, the cornices should be projected

sufficiently far to protect the walls and all exposed upper surfaces of

the plastering. The farther this projection, the more certain the

safety of the plaster, especially in the northern sections of the

country.

The essentials for successfully-wearing exterior plaster applied

in modern fashion, are: A well-seasoned, shrunk, and settled frame;

a solid, immovable foundation; and a carefully applied and thoroughly

worked job of plastering. The framework should be somewhat better

constructed and more carefully arranged to prevent movement or

settlement than on an all-wooden l)uilding. Other than this, the

dwelling to be plastered outside does not differ, in any part, from the

ordinary house, until the structure has been framed and boarded in.

For plastering, the boarding is then covered with a slightly better and

more waterproof grade of paper than if shingling or clapboarding

were intended. Outside of this papering, the house is furred with

strips of furring, seven-eighths of an inch thick by one and one-eighth

to one and one-quarter inches wide (for metal lathing they are to be

placed nine inches apart, for wood laths twelve inches, on centers),

and the lathing is applied upon these strips.

322

PLASTKUIN'O 11

A\i:r\i. I \in

TIh' Ix'.si laili fur exteriorpla.stcriii^'

is pndmltly tin- No. I'.t ( 'linton

win- cloth. The wire is >iiHicieiitly hirp- to In* ihinilih', ami the mesh

suffieieiitlv ojx-n to allow the mortar to press through aiui completely

fill and clo.se in over the hack of the wire, thus prot<ftinf( it frome.\p«>.s-

ure to the elements or ilamaf^e from vater and rust, even if thepla.ster

surface should leak sufficiently to admit water hehind this covering.

E.\paiide<l metal is also u.se<l for this pur|xise, hut it is not generally

consi(lereossihle to

cover entirely and j)rotectthe hack of this lath with plastering, and

therefore there is no means of certainly pn)tecting it from thejxjssi-

hilityof rusting.

Occjisionally.on a small, low hou.se of not «)ver a story and a-half «»f

wall height, the hoarding may heomittetl altogether. The metal lath

is then place<l din-ctly upon the furred studs, and plastered ImkIi outside

and in to insure its ahsolute protection from damage hy water. How-

ever, the .shrinking of the .studs opens a small crevice along each side—whicli has already been mentioned as occurring in l)ack |)lastering

—and it is thus possible that water may enter from the hack and do con-

siderable damage, even through the narrow space that this shrinkage

provides. The omi.ssion of the outer Iniarding aLso .somewhat injures

the stiffness of the hou.se, as a frame constructtnl in this way is not so

well brace<l as when the iMtarding is applied. Neither are the dwellers

in the hou.se .so completely protected from the exterior weather, as the

second air-.spaceobtained between the papering and the exterior

plastering is lost. This extra air-space is of a.ssi.stance in keeping the

hou.se more e<|uably warm in winter and c(m)1 in summer.

In the use of metal lath, it is always to l)e remi'inberetl that the

ah.vilitlf e,s.sential is to protect the lath from tin- action of wat«'r and

nist. This once done— in whatever fashion a p«Tmanent and la.st-

ing plaster surface is cnsure<l. Sometiujes the metal lath is winti

anil fasteneil I" |ier|M'ndicular iron furrings of tee-irons or angles,

held to tin- w(km1 frame with staples or.soim* similar fastening, allowing

anv |X).ssiblemovement of the fn;me lo i>c< iir without affecting <»r

.straining the plaster surface, which is by this means disas.s(K-iate«l

from, while directly sup|)orled by, the house fniine. ("nicks an»und

the windows and the angles of the buildings an- thus pn«venti««1 ; l>ut

.123

28 PLASTERING

it is a more expensive form of construction, and is not now employed

except in the larger and more expensive residences.

From the use of wire lath, there are occasionally obtained small

surface cracks, especially if the lath joint happens to come at a placewhere some strain is afterward placed upon it, and particularly where

it is weakened from the movement of adjacent portions of the build-

ing. For instance, if a perpendicular lath lap is made on the line of

the edge of the window finish, a crack on the line of this joint is almost

certain to appear in the plaster, extending both above and below the

wood-surrounded opening. Care should be taken to cut the strips of

lathing so that the joint will come at least nine or ten inches on either

side of the edge of the window or door finish. All furrings should also

be kept away and back from all angles, internal or external, upon the

walls, so that a certain clinch may be effected by the plastering at these

important points.

WOOD LATH

Wood lath is occasionally used, and, in certain sections of the

country, apparently with good results. It may be employed in two

ways—

one, in the ordinary manner, only spacing the laths somewhatfurther apart than would be advisable on the interior of the dwelling.

The other method consists in laying the laths diagonally over the

building in such a manner as to form a criss-cross lattice-work. In this

case the distance between the laths is from three-quarters to seven-

eighths of an inch, so as to allow the plaster to enter easily and form a

solid clinch behind these lattice openings. The purpose of the diagonalcriss-cross lattice is to provide more or less flexibility for the wall

covering, so as to take up, without injuring or cracking the plaster-

ing, a certain amount of the movement that may always be expectedin a wooden-framed dwelling. This method of employing lath, by the

way, is in most localities almost as expensive as the use of wire or metal

lath, which is probably a safer and surer material to employ. As largeand as good a quality of heavy wood lath as can be secured, shoukl be

provided for exterior work. Lath cracks are also then to be expected,from the same reasons that apply to interior work; while the mortar

should be somewhat softer and slower drying when used upon this

material than when employed upon a metal surface.

If possible, it is advisable so to arrange the work upon the house

that, after the completion of the frame, some time will still elapse

324

l'LA.STi:i{I\<i 29

iM'forr tlu" plastjT isu|)|)lii-<i.

If tin- fniiin- can Ik* l»«)iinl«'<l in, aiuJ

tlic iiitrriiir nf tin- lioiisr plastcn-tl ami fiiii.slt<*<l imhUt urtiiidal heat

t|iiriii;j tlu' winter, and tin- exterior|>la.ster

ai|ile<l in the sprinjj, |»n)l>-

ahly ihe l)e.st resiiUs are to he exiMfti-tl.()|)|x>rtunity is tlien |>n)vi(le«l

for the frame to shrink, settle, and eontraet. ^h)St of the \vei<;ht to Ix*

|)hic-etlinsi(h' of the huilihn<; is then also installe<l before the exterior

surface isa))]>lie<I,

so that iniieh less strain and movement mav Ix*

exjM-ete<l afterward to atleet it than would \n-|>n)ijal>le

under the

opjxtsite ctMiditions.

iM TTI\(i ON I fir PI \Sli.k

Exterior plaster re<|uires thn-e-i-oat work. The lirst or seniteh

coat is indis|)ensal>le when metal or wire lath is use«l, Imt alm<tst

ecpiallv im])ortant over wo(m1 hitli. This first coat should i)e seratehe<l

or rou<:hene<l while drvini;, and must Ik' thorou<;hly dry before the

second coat is ap|)lied. A <;reater time ou^lit to elaj)se hetweeii tlie

applications of exterior than of interior |ilaster coals, inasmuch as it

then heconn'SjM)Ssil)l«'

to cut out many of the larijer and more im|M)rt-

aiit cracks than have had time to a|)jH'ar, and to j)atch them before

the seconil coat is put u|)on the huu^c Tlie second or lin>wn coat is

then the less likely to crack; and, if a further extra time is allowe«| the

plasteriiif^ to dry. it can also he patchctl at the last moment before the

final sla|)-<lash or finishini; coat is put u|n)n the walls. This slower

pro^'ress aids in <,'ivin<j a more permanent job ami one that is at the

.same time less likely to ^ive annoyance from surface cracks aftt-rwanl

making' their appearance in the fhiish plastering.

The i|uestioii of pro|M)rtion in mixin;; th«' plaster is tpiile as

variable hen' ais in the ca.se of interior ])laslerin;;,and it is e4|ually

im|>ossible to n'lvv ab.solutely definite dinclions. hilferent j>lastenTS,

each beinj; piided bv the experience obtaine<l from working; in dif-

ferent .se<-tionsof thecoimtry, j)refer their individually ditTerent ways of

|)n>|)ortionin;,' or mixing; tlu-ir materials. In tin- lirst ("oat. cement is

added to the lime mortar in prn|)ortions varyin;,' U'twet-n ten and forty

|M'rcent of the mixture, ."^omc |)lasterers preh-r that the first e»»at

.shoidd be le.vs stilTened with ci inent than the sretind. With others

llic reverse is true; uliilc, contrary to the p-neral sup)>osition, the

exterior coat a|)pears in the majority «if eji.ses to contain only that

amount of cementn«-<'e.s.sary

to provide the lone or color that is d(*sinil

32 ft

30 PLASTERING

for the exterior treatment. Conditions also greatly affect these propor-tions. When the plaster is added last on a well-seasoned and shrunk

frame, for instance, it is worked stiffer than when the building is newer

and still far from finished.

The final coat for exterior plaster is generally applied as a slap-

dash finish, the surface texture being given by the throwing of hand-

fuls of variously sized pebbles or gravel upon the fresh outer coat, thus

pitting or marking up its surface. The smaller the size of the particles

employed for this purpose, the more likely they are to stick and remain

in the fresh putty, slightly tinting the surface with the color—if any—

of the gravel employed.The coloring of exterior plastering is done in much the same way

as when it is used inside the dwelling. As a rule, it may be said that

not sufficient consideration is bestowed in this country upon the

possibilities provided by the use of color for exterior plaster work.

It is agreed that the utmost care to prevent absolutely any leakage

is necessary on the part of the workman in the carrying out of this class

of work;and it is here that the success or failure of exterior plastering

most often hinges. Of course, the joints occasioned by the juxtaposi-

tion of the wood finish and plaster around window and door openingsoffer many opportunities for leakage. The plaster should here be

carefully flashed; and, if possible, an outer architrave backhand should

afterward be put on so as to cover and protect this joint. Otherwise,

a key should be provided for the plastering, by cutting away or hollow-

ing out a space near the inner edge of the wood facure, into which the

plaster may be pressed by the workman, and leakage thus preventedeven if the wood, as is quite likely, shrinks slightly away from the

plaster after it has been put in place.

The problem of making tight this exterior plaster wall is com-

plicated and rendered more difficult when it is divided into panels by a

so-called half-timber treatment. In this style of design, a great numberof joints between plaster and wood are occasioned where the wide

wood boards are almost certain to shrink away from the plastering,

and where, too, it is impossible to protect these joints by outer appliedbattens in any way capable of covering such an opening as may occur.

Thorough flashing on all upper exposed surfaces, assisted by protecting

overhang of the roof eaves, and broad keys provided for the entrance of

326

ri.\s'n:in\(; 3i

the piaster at all |m r|H-iiilicuhir ami ln\vi-r iinri/.oiitul juiiils, must uiinu'

Ih- rrliitjii|xiii.

I'lidcr III) c-ircuiiistaiKTs, so far as tin- lasting valiu' (»f tlu- work is

coiiffrriiil, (joi's tlu' iiiixtiiri' play viiiii|M)rtaiit

a part as tlic f.\|M-ii(ling

of {jreat can-ii|)<)ii

tin- tli<»n>iiijli .siirfa<iii^. wtirkiiij^, aiitl iiiiisliiii^ of

till- ninrtar, prrssiii^ it iiitorvcrv cn-virr provi<lcy the finish, an<l

takiiij; everv j)reeaution to work out all piiilioles or other tlef<fts where

water could |>ossil>lv jMiictratc tlu' surfa< c. I'lvery care and endeavor

is directed to proviijiu^ a sohd, «'Venly workc*!, and jM'rinanent (.-oating

which will, in every |M)ssil)le way. throw oil' ami prevent nioistim* In-ing

ailniitt*-*! into the space hack of the plaster coating—that vulnenihle

|)ortionwhere its attack is most enVctually con<-eale<l and most to l)e

drcadc<l.

The exterior plaster trealment of a cenn'ut or concrete wall is u

prohleni that from now on will lontinue to he of rapi<lly increasing

impfirtaiice. Here, however, it is hut necessary to use the cement as

nearlv tiiat as fM)ssil»le, adding lime or a make of whit«' cement in case

a brighter surface color is desirahle. 'I'he prohleni of the a-sthetic

treatment of concrete construction is one that re<|uires se|)an»te and

|)articularconsideration. Its solution has. as yet. heen hardly

attempted. Hollow terra-<'otta tile is another mat«'rial that is JM-ing

nKwlernlv u.se«l more and more as a .structural hase to take an exterior

plaster surface linish.

The student desiring to ohtain a wider knowledge of tin- intricate

suhjci't of exterior plastering, may he refcrre«l to several articl«-s pul>-

lishe<l in the l'.M)7 numix-rs of Tlir Arrhitrrtiiral l{iriru\ Hoston. For

a work treatintr historicallvand practicallv of iheenliri-art and cnift «>f

plastering—within and without the dwelling—see Mr. \\ llliam Millar's

treatise "IMastcr, I'laiu .iiid I )e<-orativc." It would he as well to

n-memher, in consulting the latter voliuue, that it was i.ssu«-«l in 1S07,

and that the subject is trcateil from the |)ointof view of an Knglish

workman, accustomiil to methods and materials Munewhat dilTcrent

from those conunoii in .\uierican practice

327

EXTERIORS AND INTERIOR OF HOUSE SHOWN IN PLAN ON PAGE 331

PAINTING

IntrcKlucton. Tlic first thiii^ a tii.iii wishes to know wlu-tj he

eoriteiuplatt's painting a house, is the cojil. Tliis will ohviously (le|M'iii|

on tiic f/st of lal)or, of materials, and tin* kiml of materials chosiMi.

The <jutsi(le of a house is paintnl, «'ithfr in whoU- or in part ; the interior

luav Ih' painteii or varnished. Some houses havr tlu-ir walls partly

(•overitl with shinj^les; these shinj^les are sometimes |Kiintfi|, and

sometimes— in faet, often—left unpainte<l ; hut what is calltil the (rim—that is, the boanlint; about the eaves, windows, doors, the l)ase-l)oard,

and eorner-jjiec'cs—is painte<l. Shirifjles, either wall or roof, are often

staintnl with a ereosote stain eonsistinj; of a eolorinj; matter iliss<j|ve<l

or susjhmhKhI in a litpiid ealh^l crronotc, whieh isapplii-tl for the purf)oso

of preserving tiiem; and thouj^h instanees ean he eiteil in which wall-

shinjiles that were never slainrd are still doinj; <;ood service althou^'h

ijelievi-d to he now two hundn-d and lifty years old, yet the \\i>L' of

creosote will undtnihtitlly prolonj; tin- lifi- of nKHlern, sawn shinf;les.as

it is noxious to insirt life anil a j)owerfnl ileterrent of natural di-cay.

The color of unpainted new shin<jles is jjenerally dislikitl; hut aft«'r

four or five years wall-shin<'les take on a beautiful, soft color. 'I'he

(jue.stionof staininj; shinfjies is a matter of taste.

Mo.st hou.ses are exteriorly painte<| with paint basnl on white lead

(tr zinc. Some idea of the co'^t may perhaps be jraiiuil fn)m the

followitifj c"onsi«lerations:

Wliitc lead is sold cither Rrouinl witli :i littli- oil to a tliick paste, or

Icsw coinnionly— in thi« dry state

A mixture of KM) pountls of dry wiiito load wit li "> Kallons of linseed

nil, make.s tij K^llons of paint, weinldiiR 21.3 ll)s. jM'r unl.

.\pi>ro\itiiate fiKiires an*: 15 n*s. paste lead and )>..') ll).><. oil equal.s 1 ^t\\

(1 gnl. oil e<|uals 7.7 ll>s.); II lbs. dry lead and 7J ll>s. oil ei|iinlH I gal.

A niixtun^ of 100 pounds of white zinc and S\ )!iU. oil, inaki>s U)\ i;al of

paint; 12 ll>s. zinc and 1 K'>I- "! niake 13 i;al.. or <.t.*> Ihs. xine and .'i.7 ll>s

oil make I i;al. whito zinc pnint weiKhin^ l.'i.'J ll>.s. l>ark-co|on>d paintsmade from iron oxides, orhers, and the like, wei^h I'Jto I I poutuls |M'r gallon,

l>ut exact Jiunn"" i;iiitiot he given, as thi> raw m.'iterial.s dilTer >;rej«lly.

Here shoiiU Ih- noted the dilTrrcnce U'twcen tin* priming et>at and

the suc<'i>e«lin^ ones. ,\ primiiuj coal is the first (x)at applietl to the

320

PAINTING

clean wooden surface; it diflFers from the other coats in containing more

oil, because the wood will soak up the oil and leave the coloring matter

of the paint on the outside.

To make the paint for the priming coat, take a gallon of the paint

already described and mix with it a gallon of raw linseed oil. Paint

thus made is, of course, lower in price; it is also much thinner; but

such is the absorbent power of the wood, that the priming paint does

not cover as much surface as the succeeding coats per gallon. A

gallon of this thin priming coat covers 300 to 400 sq. ft., while a gallon

of second or third-coat paint, well brushed out, will cover about twice

this surface; this is because the surface for all but the first coat is hard

and non-absorbent. Priming coats are used for both outside and

inside work, as will be described later.

The dark-colored paints are usually cheaper than those made

from lead and zinc, and if made of good materials are not inferior in

durability ; the extraordinary claims made by the zinc and lead manu-

facturers are to be received with much doubt. Some of the dark-

colored paints are the most durable that can be applied on wood. The

chief cost of painting is, however, that of labor, which varies according

to locality and other conditions, seldom being less than twice that of

materials.

For light-colored paints, it is better to use raw linseed oil to which

pale japan dryer may be added, as described later; for dark colors,

either this or boiled oil, boiled oil being darker in color. The cost is

practically the same; also the durability.

On inside work may be used either oil or enamel paint, as

described later, the former being the cheaper, the latter the handsomer

and slightly more durable; or the wood may be finished in its natural

color, by varnishing it either with an oleo-resinous varnish or with

shellac varnish. The oleo-resinous varnishes darken the wood very

appreciably, while white shellac varnish keeps it more nearly in its

natural color; although the latter does not prevent the natural darken-

ing action of light, it may retard it. Shellac varnish is the more expen-sive finish of the two, if well applied. \Miat is sometimes called oil

finish generally consists in the application of a cheap varnish called

hard oil, which is usually made of common rosin, linseed oil, and ben-

zine. Its only merit is that it is cheap.

330

FIDOT FL(2)B PLAN OECOND TLGDE PLANacAi.E. ?.i.f.?-> y t ? ? ? 'p

v'f- ?aET ocALB y I f ?i f t;r? ? f'l 'r

> feet

SUMMER HOME OF DR. J. B. McFATRICH, LAKE GENEVA, WIS.W. Carbys Zimmerman, Architect, Chicago, 111.

Frame House Built In 1906. Plau is Conditioned by Narrowness of Lot Overlooking the Lake. The InterestingFeature is the Screened-in Porch, which, by a Series of Folding Doors, can be Made Part of theLiving Room. The High Frieze in the Living Room is Decorated with Woodland

Scenes Showing the Lake and Hills in the Distance. Exterior andInterior Views Shown on Page 328.

I'AINTINC

It would imli'ttl Im--j)Oii.siltlf

to apply lu'itlitT |)aiiitnor vuniiiih,

but iiunly to s;itunite the \vo(kI with oil, and this would Ik* truly an

oil finish; it would, however, make the wo«j*l <lark and dinj^y, and

would nadily retain dirt, ami is a pnietiee sehloin followed exeept

sometimes on floors—esix-cially kitchen floors—and sink shelves.

These are at frequent intervals oile<l with a mixture of e«|Ual jMirts

boiletl oil and turpentine.

It is till" j)urposf of this Instruction l'a|Mr to ih-scrilu- only {:«km1

anil apj)roved methods. It will readily he understtKxl, and will

certainly he ohservetl in practice, that these methods may \w ahhn'-

viatetl hy the omission of some details that are heresj)ecifieti

as desir-

able. For instance, it is diflicult to get interior finish .siindpajxntl or

nihUeil lutween coats, even if so contracted; hut this is the ri^'ht

practice. Two coats of varnish often have to scr\e in the place of

four. No one, however, neeils to he told these things. The methods

herein descrihed are not lu.xurious or extravagant; they are, on fairly

giMxl hou.ses, truly economical; and we are not considering temp<jrary

structures.

It is not uncommon to find part of a hou.se, as the living nK)ms,

fini.shed in varnish, and the kitchen and pantry paintinl with oil

paints,which are lighter in color and more easily renewe<l. The

sleeping rooms, on the other hand, are often fini.shed in enamel paints,

hecau.se color effects are desired to harmonize with the furnishings;

and hathrooms are almo.st always done in enamel for .sanitary con-

siderations. The taste and inclination of the owner are to Ik; con-

sulted in regard to all these matters.

PAINTFIRS' SUPIMJIIS

Pigments and \ chicles. Paint is a mi.xtun" I'f a (inely-<lividt^l

solid .suhstance with ti lii|uid which, when sj)ri-ad on a soli<l surface

with a hnish or otherwi.se, will adhere and in a short tinu- fonn hy

evnjKinition, or more connnonly hy oxidation—a .sonu'what hard and

tough film, 'i'he finely divided solid is caUetl the piijnirnt: the liipiid

part, the vrliirlr. The most couunon vehicU- is linsntt oil. This is

an oil ohtained hy pressure (or cxtnictitui hy .solvents) froni fla.\.see»l.

When spread out in a film an<l ex|)o.sed to the air, lin.seeil oil is ct>n-

verted into a tough, leatlu n-, <lastie .suhstance calletl linnxiti, in.solnhh-

in water and all eonnnon .solvertts. This <-hangr is hnMjght alxiiit hy

r^r^t

PAINTING

absorption and chemical union of the oxygen of the air, whereby the

weight of the oil is increased about one-fifth or one-sixth. It is there-

fore a mistake to suppose that oil paint gets dry as whitewash does,

by the evaporation of the liquid. Instead of that, it gets heavier.

There are some other vegetable oils which have this property in some

degree, but none which are used for paints to any considerable extent;some are used a little for artists' colors.

Linseed oil should stand at least a month or two before usino-.

It should then be perfectly free from sediment or cloudiness; if it is not

so, this is a sign that the oil has not been properly aged, and such oil

is not fit for making paints. In this natural state, it is called raw oil;

and the price of linseed oil as commonly quoted refers to raw oil.

Boiled oil is this raw oil which has been heated, usually to 450° or 500°

F., with the addition of a small amount of oxide of lead or oxide of

manganese, or a mixture of the two (occasionally some other lead or

manganese compounds are used). Boiled oil is darker (browner) in

color than raw oil, but differs from it chiefly in that it dries five to ten

times as rapidly. A thin film of raw oil on a glass or metal surface

will dry at ordinary temperatures in five or six days, so as to feel no

longer greasy; but boiled oil will do the same in a day or half a day.Oil dries best in warm, dry weather and out of doors.

The pigment is mixed with the oil by stirring the two together.This is usually done by power, in a vessel called a paint mixer. Themixture should then be run through a paint mill; some paint mills are

of steel, but the best have a pair of mill-stones, between which the

paint is ground and most thoroughly mixed. Paints niLxed in this

manner are much better than those which are mLxed only by stirring.

Besides oil and pigment, paint sometimes contains a volatile thin-

ner, the most important thinners being turpentine and benzine. Tur-

pentine is a well-known essential oil, volatile, boiling at about 320° F.,

but evaporating at ordinary temperatures when exposed to the air.

Benzine is a mineral oil, lighter than kerosene and heavier than gaso-line; the kind used- in paint and varnish is called "62-degreebenzine," its specific gravity being 62° on the Baume scale for liquids

lighter than water. Linseed oil weighs 7.7 lbs. per gallon; turpen-tine, 7.2 lbs.; and 62° benzine, 6.1 lbs. But linseed oil is sold by theoil makers and dealers on the basis of 7.5 lbs. per gallon.

332

PAINTfN^;

A ilrytT, ill somr f«inii, is an cssriitijil in^nilit-iit of oiljKiiiit.

A dryer is a coiuiKdiiKl of K-ail or niaii;piiu'st' (i;nirrally Unlij, solulile

in oil,aii«l is usually soKI, umliTtlir iiaiiR' ui paint dnjtr ar paint japan,

asii soluti<J!i of sui-li material in a mixture* of oil, tur|x-iitiii<-,and Im-ii-

ziiif. It is usually of such streiif^tii that an atlilition of from 5 to 10

|H-rcent of it to a raw-oil

|)aiiitwill mtke it ilry in from six to twelve

hours sulHeieiitlv to he carefully handled. I'aint.s are not <lrv enouirh

to use, until they have stood four times as lonj^ a.s this; and they con-

tinue to harden for months. The stronjêst dryin;; ja|)aiis are dark in

color; hut such are more injurious to the diinihility of the jxiint than

those which are paler, es[H'cialIy if the latter do not contain n)sin.

The huver should always ask for a 'guarantee that the dryer is free

from n)siii, if j^reat durahility in the j)aint is needtil. Not more than

10 [HT cent of aiiyilryer or japan should ever he use<l in any paint.

Slowly drying; jKiints are more durahle than '|uick ones.

In house puintinj^, the white pi<,Miients arc the most important,

Infause they are the base of all li<;lit-colorcd paints. The most

imj)ortant white j)ii;ment is irliitc lead. This is sold cither as a dry

j)owder, or (more commonly) as paste white li-ad. which is made of

(H) ll)s. dry wiiite leail and 10 ll)s. linseed oil. This can l)e thinnetl

with l)f)iled oil to make a white j)aint.White lead is a very heavy

pif^ncnt; and with a fjiven (piantity of oil, more of it can he mixetl

than of any other pijûent, except red lead. It has jjreat opacity,

f)r covering j)ower. It is discolored hy â.ses ct)iitainin<j sulphur,

hecominj^ hrown or hiack; and unlessexjx).se<l

to fairly stronj; lifiht. it

hecomes yellowish even in pure air. It is better if it has been mixcxl

with the oil for .some timi—a year or more.

ll'hitr zinc is a somewhat purer white than whiti- lead; not so

o|)a(pi<-.Three coats of lead arc reckoiu'<l npial to live coats of /inc.

It becomes hanlcr than lead, but is somewhat liable to [kcI otf; while

|i ad, aftir<'X|X)sure to the air fur a Imi;^ time, becomes dry ami |M)wdery

on its surface, and rlialk.i.

\ mixture of two parts of h-ad and ono of zinc is much likitj.

VAnr-lvad, however, is the name of an entirely dilfen-nl |)ii;ment, made

by fiirnacinj^ ores containin;; alM)ut eipial parts of lejul and /.iin-.

in which the lead is present as a sulphate. This pigment is friH" frtin

the liability to (urn brown if ex|M»s«'«lto sulphur pises; it is .sjiid to In*

not (juite.S4» pure a \\\\'\\.v a.s the

prc«'e«linj;.It is a coiii|Kkni(ively new

ana

PAINTING

pigment, but is coming rapidly into use, being somewhat cheaper than

the others. Liihopone is another white pigment of considerable merit.

Adulterants. All these pigments may be adulicrated with

barytes, or with terra alba (sulphate of lime), sometimes with whiting

(carbonate of lime). These adulterants are powdered minerals.

Barytes is a good pigment, so far as protective action goes; and

terra alba is thought by some good authorities to be unobjectionable;

but whiting is injurious. All of them are transparent in oil, and

lessen the opacity or whitening power of the paint.

From these white paints, colored paints are made by adding

tinting colors, of which the yellow is chiefly c/tro7;ie yellow, or chromate

of lead; the blue may be either ultramarine or priissian blue; and the

green is chrome green, a mixture of chrome yellow and prussian blue.

The reds are (in house paints) made from coal-tar colors, and most of

them are now fairly fast to light. Some dull yellow colors are made from

ochers, which are clays tinted with iron oxides, roasted and ground.

These are permanent colors.

The dark-colored paints may not contain lead or zinc at all. The

deep yellows, greens, and blues are made from the colors already

named as tinting colors, none of which are entirely fast to light; the

dark reds and browns are chiefly iron oxides, which are a valuable class

of paints, very permanent on wood. The blacks are either lamp-black or drop-black (bone-black) and other carbon colors; and these

are often added in small quantity to secure some desired tone or shade

of color.

The zinc and lead pigments have some action on oil, and in their

case it is considered the best practice to apply thin coats; but the dark

pigments do not act on oil, and, of these, thick coats are best for dura-

bility.

Paint and Varnish Brushes. A brush that has only a low price

to recommend it will prove a poor investment. If properly cared for,

brushes last a long time, and it pays to have good ones. The first sign

of a good brush is uniform quality from outside to center. Inferior

brushes have inferior bristles in the middle, and some poor brushes

are actually hollow. For ordinary oil painting, the bristles on a large

new brush should be five or six inches long, uniformly flexible, and as

stiff as can be found; they will be flexible enough anyway, but all should

be alike.

334

PAINTING

I'aiiit Imislu's an- round, flat, i»r uval. A favorite brush for

nnlinury out-sitk' work is what is calh-*! a jHnind brit.ih,ii la rj^e, round

Imish with stiff hristles six inchrs long. Such a bnish shuulil Im*

bridled whvu it is new—a "hridh*" hring a piwe of c-onJ wound around

tlu' hristles to sliortcn thoir t'tfiHtivc K-ngth; as tlic hristh-s Ixt-ome

worn off, thi" hri(ii«- may hi- rtinuvc-d. A 21-inch oval hnish ('2k

inches wide) is a highly satisfactory tool to visv in general painting,and is the brush recttniniench-d by the paint cununitte*- of the American

S<K-iety for Testing Materials. It is worth noting that this c«jinmittec,

made up e<|ually of expert paint manufacturers and ex|XTts employe*!

by the large consumers, unanimously agreeil that no larger brush than

this should be u.sed in making j)aint tests.

The use of brushes five inches wide is common for outside work;but wiiile such brushes mav be had of the liest (lualitv, thev are heavv

and laborious to u<.v, and the workman who uses such a brush will not

brush the j)aint sufliciently to get the best result. If a flat brush i-s

used, it should not exceed 3^. inches in width; and three inches is

better. A gotxl 21-inch oval varnish brush is a most excellent brush

for all large work in either paint or varnish. The painter should also

have a go<Kl Ij-inch oval brush for smaller work, and a number «>f

roimd or oval brushes, called sash tools, of different smaller sizes, for

more delicate work, such as .sash and frame jjainting. Stiff-bristle

brushes, which have b<>en worn off short, are suitable for such work as

nibbing-in filling. For varnishing large surfaces, flat bristle brushes

21 inches wide are goinl; also similar ones 2 inches, 1\ inches, aiitl 1

inch wide arc useful. .Ml flat brushes should have chiseled inlires.

For flowing vaniish, it is nece.s.sary to have thick, flat, camel's-hair

bni.shes, rumiing u\)(o '.',\ inches in width, although most hou.se

varnishing may be done with brushes not over '2\ inches wide.

Besides paint Itrushes, the workman will m-e*! .souu* onlinary

smdihiiuj hrushis and one or twop.-iinler's diistiiuj hruslus, to have the

.surface pn)j>erly cleaned.

Steel-wire brushes, with stiff steel wire instead of bristles. sha|Ht|

like MTidtbing brusln-s, are used for cleaning off old pjiint and for

cleaning structural metal work. These are of various si/^vs; and the

.steel wires jire «»f different lengths and sizes, hence differing in stiffness.

They may Im* had at hanlware ston-s.

Care of r.ruslics Hair and bristle brushes nuist U- kept dean

33a

8 PAINTING

and soft; this can be done by care and faithfulness. They should

not be allowed to become dry with paint or varnish in them. To

prevent this, wash them out in oil or turpentine as soon as you are

through using them ; or they may be left in the paint or varnish for a

few days. They may be kept over night by wrapping them very

closely in paper if they have been used in a slow-drying material; in

this way they may be carried from one place to another. Brushes

should not be left to dry with even clean oil or turpentine in them; if

they are to be put away, they should be well washed first with soapand water, then with clean water, then hung up until thoroughly dry.

In use, brushes are best kept in what is called a brush safe. Adeep wooden pail, with nails driven in its sides at different distances

from the bottom, and with a close cover, makes a good receptaclefor brushes. The brushes have holes in their handles, or loops of

cord tied to them, and are hung on these nails; their bristles dip into

some turpentine or oil in the bottom of the pail; they are so hung that

they do not dip into the liquid above where the bristles project from

the binding. If brushes are left standing on the bristles on the bottom

of a vessel, they soon become one-sided and distorted in shape. Tin

brush-safes may be bought of any large dealer in brushes.

A brush which has dried with paint or varnish in it, may be

recovered by soaking it in a non-alkaline varnish-remover. This will

in time soften it so that it may be used again, but it is not improved bysuch treatment. Brushes used in shellac should be washed out with

alcohol instead of turpentine or benzine. No brush is good unless it is

clean.

Fillers, Fillers are of two kinds—paste and liqiiid. Paste

fillers are something like a very thick paint, and are composed of somesolid powdered substance, usually silica or powdered quartz, mixed

with a quick-drying varnish thinned with turpentine or benzine.

This is applied to the dry surface of the wood with a stiff, short-bristle

brush, or is put on with a clean, white cotton cloth, and well rubbed into

the pores of the wood. After half an hour or so, the surface of the

wood is wiped off with a wad of excelsior or a clean cloth or a piece of

felt. A liquid filler is a quick-drying varnish; and most of the liquidfillers on the market are cheap rosin varnishes loaded with dryers,and should never be used.. Paste fillers are the best in almost all

cases.

336

TAIN riNC

UOlSi: l'\l\IIN<i

Inside \S (trk. All wIikIow and «l<M»r frames, wlu'tlu-r tlu-y art- lo

1k' fiiiislutl with paint or varnish, .should rrcrive a mMHi c*oat of paint

niadi- with some cluaj) pi^'mcnt, such as inin oxidi-, and ljoil«d <»il,

a|)|>liidto till- hatk of the fniini-, hcfort' tlu-y art" hnjuj^ht fnjni the

shop t«» tlu' house; this prevents tlu- absorption of moisture ami hin-

ders «le('av. If they are to he painted, they shotild receive a priming

coat in the shop, if |»ossil»le;if not, it should he applietl as s«K)n as prac-

ticahU'. I'he priming coat iscompost-d of white lea<l and hoih-^l oil or

raw oil, with five to ten per cent of dryer; and should he almost all

oil, with very little ])i;,Mnent. Turjientine is not a ^xmI thinf; in a

priming coat, hecause the object is to fill the jM)res «)f the wixKl.and

turiH-ntine evaporates. As .soon a.s this is »lry to the touch, all holes

are to he filled with j)Utty.The hest putty for this pur{M)se is white

lead j)Uttv,made hy mixing a little raw oil with dry white lead,

or hv adding ilry lead to j)aste leiid until it is of the right con-

sistencv. This kind of i)Utty hardens <|uickly as compartnl with

common putty, and is the hest for this purpo.se. A steel putty-knife

should not he used on interior woodwork, as it is almost certain to

scratch it; a hardwood stick, suitably shaped, slutuld he u.setl. .\11

cracks, joints, ami nail-holes should he canfully filled. .Ml knots

and .sappv places should he varnished with slu-llac varnish; this pre-

vents the pitch and moisture from attacking the paint. The shellac

shoidd l)e applied where it is needed, hefore the priming coat. The

priming coat should he givi-n time to get <|uiti' <lry; at least a day —two

(lavs, if po.ssihle;an<l a week is better yet. Then it is ready for the

.secontl coat. This shoidd contain a considerable amount of turpentine.

If no turpentine is used, the surface is likely to be glossy, ami the next

coat of |)aintwill not adhere well; but by rej)laeiiig part of the t>il with

turpentin*', we get what painters call a flat <•<)(//— that is, «)ne which i.s

not glossv; if this is ma<le from |)aste lead or any |)ast<' paint, it <'«n

be pro<hieed bv tliiiuiing the |)aslewith a mixture of oil and tur|M-ntine

in eoual j)roporlions; some |>ainf«TS prefer one-thini oil and tw«w

thirds turpentine. This is for inside work only. This coat .sh<»ul«l

be allowe<l to dry thoroughly; if it takivs ten hours for the paint to U*

drv enough to hamlle, then at least four times l<-n li«)urs addHumal

.should elapse before the next coat is ap|)lied ; thi.s is a giHxj giMiemI nilc;

and as much mun- time as |)o.ssible.shoidd be allownl. If {\\v fmi.sh

337

10 PAINTING

is to be ordinary oil paint, the next coat may be paint, thinned with

about half as much turpentine as before, or with no turpentine at all.

In the latter case, when the coat is thoroughly dry, it must be carefully

examined, and, if glossy, it should be rubbed with something to take

off the gloss; curled hair is often used, or a light rubbing with pumiceand water. Then the final coat, which has no turpentine in it, may be

applied.

But if the finish is to be with an enamel paint, the second coat,

when quite dry, should be very lightly sandpapered with fine sand-

paper, and the third coat should be of like composition to the second,

treated the same way; then the enamel paint is applied. For a really

first-class job, when this is quite dry, it should be rubbed down with

curled hair or pumice and water, and another coat of enamel put on.

This may be left with the natural gloss if desired ;or it may be rubbed

with pumice and water to a flat (dull) surface.

Painting Plastered Walls. Old plastered walls may be painted

with oil or enamel paints as though they were wood, remembering that

the priming coat will have almost all of its oil absorbed by the plaster.

New plastered walls do not take paint well, on account of their alkaline

character, which gradually disappears with exposure to the atmos-

phere. It is well to let a wall remain unpaintcd at least a year. But

if it is necessary to paint a freshly plastered wall, the wall is prepared

by some painters by washing it with a solution of sugar in vinegar,

the sugar uniting with the lime to some extent; or—more commonly—by washing it first with a strong solution of common alum and then

with a solution of soap. After this is dry, it is washed with clean

water, allowed to dry, and then painted. The alum and soap form an

insoluble compound which closes the pores of the plaster to some ex-

tent, and prevents the lime from acting on the paint.

Outside Work. Exterior paints are more elastic, as they need

to be far more lasting, than those used on interiors, since the effect of

exposure to the sun and rain, destroys paint more than almost any-

thing else does. Paint on the interior of a house will last almost

indefinitely; but on the outside the best paint is not very durable. The

surface, if new, should be cleaned by ])rushing; knots should be

shellacked; after which the priming coat should be applied. This

may be the same paint which is selected for the finish, only thinned

with boiled oil (or raw oil and dryer), using one to one and a-third

338

rAiNTiNf; 11

giilloiis of oil to eiifli gallon of paint. Tlir niisoii why onlinarv jMiint

mav imt he ustti as a priiiu-r, is that tlu* wimhI ahsorl)s tht* oil. leav-

ing the pijjineiitas a ctinparatively iiori-adhesivr |H)\v<ler

on the sur-

face, from which the next eoat will pn)l)alily jm-^-Ioff. 'I'he next step

is to putty np all nailholes and other (iefe<ts. For the see«»ml eoat,

many experts a«lvise the addition of half a pint of tnrjMiitine to the

gallon of j)aint; others make no a<l<lition to it. 'I'he third eoat is

applie<l after the second is thonnighly tlry; if a week or a montli can

ilapse l)etwicn these coats, so much tlu- better.

Repainting;. If the old paint has heeii on a long time, it is liahle

to Ik' jH'rmeated hy minute cracks, which admit m<jisture to the surface

of the wckkI and loosen the j)aint.If now we paint over this, the new

paint, which shrinks in drying, tends to pull <»ff the old paint, and of

course the whole peels off in patches. If the oKl pjiint is in this state,

it must he remove<l before tlie new paint is applied. This can Ik-

ilone hy burnimj off.Vor this work a paiiilrr'.s

torch isretiuiri-tl,

which is a lamp burning alcohol, gasoline, or kcro.sene, and is .so con-

stnicted that a blast of flame can be directe*! against the surface. This

melts or .scjftens the old paint, which is then imme<liately .scra|K-«lofT

with a steel .scraper. The paint is not literally burnitl, but is .softenetl

by heat .so that it can be .scraped off. In .some cases it is suflic-ient

to remove as much asjxj.ssibic

with a steel bru.sh; this is a brush like

a .scrubbing bnish, with ste«-I win-s instead of bristles, and, when

vigon)Usly used, will take oil' the loose ])aiMt.

( )ld paint, however, is not always in this condition. If it adhen-s

well, it may be cleane<l with an onlinary scrubbing brush and water,

and wlii'ii it is (piite dry. tlu- new paint may be applied. ."Nunrtimes

tlie paint .seems in goo4l condition, only it has fade<l and lost its lu.ster;

in such cases a coat of boiled oil, or niw oil with dryer, is all that is

needed.

It is well to paint the trinj—that is. the window-casings, dtM)r-

casings, corner-pie<es, and the like before painting the Ixnly of the

house; then the paint can i>e applieil to the Hat surface's more neatly

than is otlu nvisc- likely to be done. Paint should be appli««d in thin

CfMits, Wi'll brushed on; it is not umisual to M-e|taint

come «>IT fnmt

n-H-ntnint angles while it is still go«Ml on Hal surfaces. UvaUM* it was

diHiciilt to brush the paint pn>perly in thosi-|)lnc'«'s.

Then' i.s a gn*«t

dilTen-nce in diimbility lu-tween a thin|»!iinl

llowitl on with a largi*.

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12 PAINTING

flat brush, and one of proper consistency well brushed out with a brush

of medium size. In all painting on wood, it is desirable to brush it on

with the grain of the wood; and by painting only a few boards at once,

we may avoid laps by painting the whole length. Rough surfaces

hold paint better, and more of it, than smooth. A gallon of paint will

cover, one coat (on a painted or well-primed surface), about GOO square

feet, not flowed on, but well brushed out in a thin film. The primingcoat will not cover more than 300 or 400 square feet to the gallon. In

measuring the outside of a house for surface, make no deductions for

doors and windows; if the trim is to be painted a different color, from

one-sixth to one-third of the paint will be required of that color.

Paint should be stirred frequently while using. A coat of dry paint is

from -^~g to T.oVo of ^^ ^nch in thickness.

Roof Painting. Roof paints should contain a larger proportion of

oil to pigment than other paints, and less dryer (or none at all).

Many think that the addition of ten to twenty per cent of fish oil to a

paint for roofs is advantageous; fish oil greatly retards drj^ing and

prevents the paint from becoming brittle. Tin roofs, if new, should

be thoroughly scrubbed with soap and water, or with pieces of harsh

cloth, such as burlap, well wet with benzine. They may then be

painted.

Paint dries relatively fast on roofs; but as a roof paint is very

slow-drying, plenty of time must be allowed between coats. A new

roof should receive three coats. ]\Ietal gutters and spouts are to be

treated the same way. Do not forget that new tin or galvanized iron is

difficult to paint; have it very thoroughly scrubbed, even though it

looks perfectly clean, and then rub the paint on well with the brush.

Metal spouts will usually be painted the same color as the wall of the

house.

Sometimes shingle roofs are painted with fireproof paint. This

is not really fireproof, but considerably retards the spread of fire, after

it has become thoroughly dry; when fresh, it does not even do that;nor

does it have much effect after it has been on a year or so. It may be

made by adding to a gallon of any good paint about a pound of

powdered boracic acid. A\Tien strongly heated, this material fuses

and forms a sort of glass, which keeps the air from the wood. It is

after a time washed out by the rain.

Canvas roofs are prepared in the following manner: The canvas

340

1*A IMING 13

( l()-<)unce (luck is often iisiil) is first iiailttl down, care In-in^ taken to

draw it tight ; it will show some wrinkles, hut these are not to Ik- allowed

to accumulate to form a larj;e wrinkle or fold. Then the canvas is

thoroui^hly wet; it shrinks, and all the little wrinklestlisii|)|M-ar.

It is

a common practice to paint it while it is still wet, this Ix-iuf? an e.\ce[>-

tion to all other practice; hut some wait luitil it is dry. The writer

has heen accustonutl to the latter niethiHl, and has not found that the

canvas shows wrinkles on dryinj^, while the results are all that can Ix;

desired. A well-paintetl can\as roof is very durahle and siitisfactory.

l>\!NTI\(i STRICTI ini. MITM.

Steel is a more perishahle material than woimI, arwl more diflicult

to paint. Without rej^ilar expenditure for maintenance, wiMxlen

hriilfjes last lonj^er than steel ones; there are wocMlen roof In-ams a

thousand vears old; and in)n i*oofs are .so short-lived that thev are usetl

oidy over furnaces and the like, where wocnlen ones would take lire.

The painting of structural steel is therefore injj)ortant; antl it is also

diflicult, if wc are to judge by results.

In the first place comes the prej)aration of the surface. When

we paint wo<mI, we have the surface clean and dry: and then we soak

it with oil, so as to have the paint hound to it in the most intimate

manner. Iron and steel, on the other hand, always come to' us dirty,

and covered with o.xide; and as the surface is not |)on)Us. the |)aint

does not jjenetrate it, hut has to stick on the outside the best way it can.

If we paint over the dirt and .scale, and that ever comes olf, the jKiint

comes off with it; if the metal is actively rusting, and we paint over the

rust, the corrosion is perhaps made slower, hut it does not stop.

.\ir iiiid moisture cau.se rust; if we can ket-p tluiii away, the metal

will last; hut, unfortunately, all paint is very slightly porous, an<l if

e.\|)ose<lto the weatlur if in time deteriorates. The most es.sential

thing in |.ainling metal is to '/«/ ///'jidiiit

tin thr iintal, not on an inter-

niiiliate coating.

There are onlv two wavs to clean sferl perfectlv. One is l)V

jtickling it in dilute acid (ii.sually10 to 20 jht cent sulphuric aei<l),

followed hv washinu to niiiove tin- arid; and the other is hv the use

of thivsjind-hlast. Neither of iluvse pnM'e.s.sesis availidtle to theonlinary

painter, who nmst do the next l)«'st thing. This is to remove alvsolulely

all dirt and all Iikksc scale and oxidi-. l''irst clean olT the dirt, if any,

'M 1

14 PAINTING

with brushes, as it would be cleaned ofp any other surface. Then,with scrapers and steel-wire brushes, clean oft" all the scale which will

come off. If there is any new rust (not mill scale), it must be well

scraped out and cleaned off. This is indispensable. WTien this is

done, immediately paint it, before it begins rusting again.One of the most popular materials for a first coat is red lead in

oil. This must be mixed on the spot, shortly before it is used, because

it will harden into a cake in the pail or can if allowed to stand very

long. From 30 to 33 pounds of dry red lead is to be mixed with each

gallon of oil—not less than 28 in any case. This is immediately paintedon the metal; if it is put on in too thick a coat, it will run and be uneven.

Some use raw oil, others boiled oil; it does not make much difference

which is used. The paint dries rapidly; and as soon as it seems hard,a second coat of the paint can be applied. Red lead is different

from all other paints in this, that it will finish hardening just as well

away from the air. This is because it does not dry by oxidation, as

other paints do, but by the lead combining chemically with the oil,

just as water combines with Portland cement. In the opinion of the

writer, red lead should have one or two coats of some good paint, other

than red lead, over it. But red lead is not the only first coating which

may be used. Any good paint may be used—a good graphite paint, or

other carbon paint, or some of the varnish-like coatings containinglinseed oil and asphaltum which are made for the purpose. It is

important, in using any of these, to let plenty of time for drying elapsebetween coats. Not less than two coats is permissible, and three are

desirable.

Projecting angles, edges, and bolt and rivet heads are the placeswhich first show rust through the paint. This is partly because the

brush draws the paint thin at such places. To overcome this, it is now

becoming common practice to go over the work after the first coat,and paint all edges for about an inch from the edge or angle, and all

bolt and rivet heads, with an extra or striping coat; then, when the

second coat goes on over the whole, there is the equivalent of twofull coats ever^'where.

Painting on iron, as on wood, should be done in dry weather,when it is not very cold—at any rate not below 50° F. Full, heavycoats should be used, and well brushed on. Care must be taken to getthe paint into all cracks and corners.

342

PAINTING 15

\ Ak.M>ll

A varnisli is a lii|ui(llitatlc to In- appliitl to a surfaci- in a thin

film, uliicli, on rxjx).siirr to tin- air, lianlrns into a pnitiftivt- coating

that is usually glossy and almost transparmt. Thcrt- arc two principal

classes—spirit and oleo-rr.titioii.s ranii.s/us.

."^[)irit varnishes, of which .v//r//«r* is the most inijxjrtant, arc made

by ilissolvinga resin (or sometimes some other suhstancej in a volatile

solvent, such as alcohol. They tiry by evaporation, the solvent going

off and leaving the resin spread out in a thin film, the li(|uid or vehicle

having really ser\'c<l as a mechanical means of sprea«ling the resin over

the surface. Shellac is a ri-sin which conies on the market in large,

thin flakes. It may be di.s.solved in dcnaturtMl (or any other) alcohol

in the following manner:

Put th»> alcohol in an eartiicnwan- jar, and wi-igh out five j)()Unds

of gum shellac for each gallon of alcohol. Just before leaving at

night, carefully and gently drop the slullac, little by little, into the jar

of alcohol, then put on the cover and leave it until morning. Do not

on anv account stir it. In the morning the fiakes of .shellac will be

soaked and swollen; but if you had stirred them in, the night before,

they would have stuck together in linnj)s. Now, during the day, stir

the ma.ss with a wfxiden stick once every hour or so; do not put any

metal in it, espet-ially iron; one iron nail will spoil the color of a whole

barrel of shellac. Hy the next morning—

perhaps before— the shellac

will be rea«ly for u.se. It does not make a clear solution, b<.>cau.se the

gum .shellac contains .some wa.x, which does not di.ssolve, and so the

varnish is milky or cloudy; it is, howevir, ready for u.se. As the

alcohol is volatile, the jar shoidil be kept coven.il; and after it is

made, the varnish should be put in gla.ss lM)ttles or clean tin cans.

There are many grades of shellac gum, the best being known by

th<' lett«Ts i> ('; but there are others nearly as good, 'i'he common

shellac is brownish y«'llow, and is calh-d oniiK/r sin liar: this is the natu-

nd shellac color. White shellac is matle from this by bleaching with

chlorine; l)Ut it is n«)t of .s«) good (|ualify as the unbleacheil; it has. tif

cf)urse, the advantage of Ix-ing much paler in <olur. White slu-llac

ginn will, on long standmg. sometimes Inrome insoluble. Shellac

• N<>T«.- Hy <">m«' i)nlnior«, tho i«Tm •varnlHh' |h ni'Vrr u»«l lo Imludn nhpllMS.

Tbnro l4, hiiwrvor. ii<> v»Utl. (ibjncilvn rrawui (or tbiiH lltnttlU|{ iho uiMof the U^rm.

34a

16 PAINTING

vamish may be thinned with alcohol, and often this is necessary.Shellac is too often adulterated with common rosin, which greatlylessens its value. This is easily detected by a chemical test.

Damar is a white resin which is soluble in spirits of turpentine—

five or six pounds of resin to a gallon of turpentine. It is the most

nearly colorless varnish we have, but never becomes very hard. It is

used to a considerable extent as a vehicle for white lead and zinc, to

make a very white enamel paint. It is not durable if exposed to the

weather.

More important than spirit varnishes are the oleo-resinous var-

nishes,which consist of certain resins dissolved in linseed oil, the mixture

being thinned with turpentine or benzine. In making these, the resin

is put in a copper kettle and heated until it is thoroughly melted ; then

some hot oil is added to it, and the mixture cooked until the whole is

thoroughly combined. The kettle is then taken from the fire, andwhen partly cool, the turpentine is stirred in. The resin makes the

film hard and lustrous, and the oil makes it tough. Thus the largerthe proportion of resin, the harder and more brilliant will be the film

;

the larger the proportion of oil, the tougher, more elastic, and moredurable it will be, and the slower it will dry. jNIost of the color of varnish

comes from the resin; the paler this is, the paler will be the varnish.

The pale gums are higher in price than the dark ones, but are no better

in any respect except color. Dark varnishes may be just as good(except in color) as pale ones—in fact may be better, for the darkresins are often harder and better than the pale ones of the same sort.

The hard and quick-drying varnishes are suitable for furniture; the

medium, for interior house-varnishes; the slow and elastic, for exposureto the weather.

Varnishing. The wood should be dry. For this reason it is

better, if necessary to clean it, to avoid washing as much as possible,

using sandpaper instead, which will also make it smooth. Of coursethe carpenter is supposed to do this, but the painter must not neglectit on that account. ^Mien in proper condition, it first receives, if it is an

open-grain wood, a coat of paste filler. The open-grained woods in

most common use are oak, chestnut, and ash. The woods classed as

close-grain woods are white pine, maple, birch, yellow pine, white-

wood, cherry, and sycamore. These latter do not needfilling. If

filler is used, it should be well rubbed in with a short, stiff brush; and

344

PAINTING 17

wlu'M it has set, say in fifteen ti> tliirty iniiiiites, it is nililKil (iff with a

haixlful of e.xcfl.siur, rul)l)iiiji acniss the ^'niin, ami ruhhiii'^; hanl, mj as

to force the filler well into the jx)re.sof the woo<l. Then it should

stand 24 to 4S hours.

When j)URhased,a paste filler is too thick to Ik? used with ahru-sh,

and must l)c thinned with ttirpentuie or U'lizine; at the Siiiue time it

may Ix* stained to any desired cohjr with an oil or varnish stain, 'riir-c

stains can he j)urchase<l of any desired color. If a close-fjrainitl smmkI

is under treatment, the lirst tliin;^ is to a|)|)lya stain if it is desiri-<l to

stain the wimmI; hut it is common |)ractice to finish in the natural color.

Stains usually re<|uire a ^(mmI deal of thimiinj; before usinj;; the amount

of thiiminf^ will determine the<li-j)th of color. Water stains arc seldom

used, as they tend to raise the ^rain of the wood.

In cleaninfjoll" the filler, he careful to clean out corners and mouKl-

ings, usm<; for this purpose, properly shapcil hardwocMl sticks; do not

use any steel tool.

Where rooms are to he finished in the natural color of the wood,

it is nevertheless a common practice to stain the window-.sashes; a

cherry or lijjht maho<;any stain is often U-sihI. Fillers are .sometimes

used on close-grain woods; hut this is not advisid)le, as they tend to

prevent the varnish from getting a good hold on the wo(mI.

Next comes the varnishing. Window-sills, jamhs, inside hlinds,

and other surfaces exposed to the direct rays of the sun, are to he

treate«l as exterior woo<lwork, and are not varnished with the ordinary

interior varnish used on the rest of the work. The floors also are left

out of account for the present. 'I'lie rest of the woodwork nreives its

first coat of varnish; apply it. as much as possible, with the gniin of the

wood, hrushing it out well in a thin coal. The varnish ought to dry

dust free (/.«•., so that dust will not sti<k (o it) over night ; Imt at least

five (lavs sill II lid elapse lielweeii eoats. When dry, it shouKl he ruhlH-*!

withcurl«-<l hair or excelsior enough to remove theglo.ss.so that the next

coat of varnish will adhere j)ritperly;a lietter result will he had if it is

lightlv .santlpapered with (HIp;i|ier.

The se<-ond coat is treat»"«l like

the lirst. The third is not siind|)apereil. Imt rulihed with eurletl hair;

thefourtln>r linishing coat may In- left widi the natural gloss, or. ifpn*-

ferred. it mav Iw ruhl>e«l with line pumice and water t«» a sn)(Ktth,«hill

.surfa«-e. Kor this pur|Mts«' the varnish tiealers .sell felt,al>«)Ut an inch

tliick, which is well wei in < lean water; a little «lry |»iuniee jiowder is

345

18 PAINTING

put on it; and the rubbing is done with this. The varnish must be

quite hard and dry before this is attempted. Varnishing, if properly

done, is slow work; that is, much time must be allowed for each

coat to dry thoroughly.

The varnish which is used on interior woodwork should not dry

too quickly; it should dry enough over night so that dust will not stick

to it, and in twenty-four hours should be hard enough to handle freely;

but if a chair, for example, were varnished with it, it would not be

entirely safe to sit on it for a week. It should, however, finally become

perfectly free from tack, which it will not do if it is a rosin varnish. At

present prices (and it is not probable that they will ever be lower) var-

nishes for interior woodwork are sold, according to color and quahty,

at prices ranging from $2.50 to S4.00 a gallon. It is in the highest

degree inadmissible to use a cheapvarnish forundercoats ; theouter coats

will crack if this is done. A good varnish that dries too quickly, such

as what is called a rubbing varnish, or one intended for furniture, has

not the durability needed for this work. It is economy to use a goodvarnish. The writer has in mind a house which was properly var-

nished eighteen years ago and has been constantly occupied by a large

family, yet the varnish is still in fair condition ;if it were lightly sand-

papered and one new coat applied, it would be like new—as good as

it is possible for a surface to be. Cheap rosin varnishes never look

well, even when new, never keep clean, and deteriorate rapidly.

Shellac. Interiors are sometimes finished with shellac. This

varnish is not used on exterior work, but it is a good varnish for inter-

iors. All varnishes containing oil darken the color of wood; but white

shellac is comparatively free from this objection; at any rate it does it

less than anything else. Orange shellac is a dark varnish, and even

white shellac darkens with age to an appreciable degree. Orangeshellac is more durable than white, and should be used wherever

admissible, rather than white; but it is usually necessary to use white

shellac for this service. If shellac is made up as heavy as has been

described—five pounds to a gallon of alcohol, and this is the standard

—it should be thinned considerably with alcohol before using on inte-

rior woodwork. It must be applied in thin coats, and given plenty of

time to dry. It is very deceptive about this; it appears to be dry and

hard in an hour, and it is hard enough to handle freely; but if we applycoat after coat, even six hours apart, we shall find that the wood is

346

PAINTING 19

liiially cuverttl with u waxy nu*^s wliuh will U- llie .sourff of nothing

hut tn)uhle. The hrst roat sinks ntpiilly into thf wimxI; a stfoml coat

may he apphttl six hours hitcr; hut aft«T that, allow two days at least

hetween coats. Shellac makes a very thin coat; so it is necessiiry to

apply a larije numlnT of coats, at least twice as many as of oleo-

resinous varnishes, to get a suflicient thickness of coating. Becioise

of this lalM)r, shellac is an expensive finish; hut it is handsome jmhI

durahle. 'I'he treatment of it, as regards ruhhing, etc., is tiie s;ime

as has heen descrihcd for other varnish.

\'arnish makers usually a<lvise that shellac should never Ix* used

as a priming coat for other varnish; this is prohahly hecause they wish

to sell more of their own goods, for shi-llac is really an excellent first

coat, except for exterior work, where it should not he used. Of course,

w(mmI shoidd he filled hefore shellacking, the.s;ime as for other varnish.

\'arnish does not, however, wear well over a heavily shellackeil sur-

face. Shellac makes a gocwl floor varnish, discoloring the wmxl very

little, and wearing fairly well, .\fter the floor has heen well varnished

with it, ver)' thin coats, applied rather fre<|Uently—

say every one to

four months, f.ccording to use—will keep the floor in fine eondition ;

and after applying one of these thin coats (of thinni-il shellac), it will

he tiry enough to use in an hour. This can he ap|)lie(l with a very

wide, flat hrush, and a man can go over the Hoor of an ordinary room

in a few mimites. Shellac hnishes should he wasluti out with alcohol

iimnt-diately after using.

I'xtcrior Varnisliing. \'arnishes<lry much more rapidly out <if

doors than within, so that it is praeticahle to use more elastic and dur-

al>le materials. The conditions, in fact, are .so .seven* that the In'st

are not giMnl enough. In the first j»lace, do not use any filler on

exterior work; it will prohahly crumhie an<l come out. Do not use

.shellac; as an undercoat exjxtsed to the hot smi.it will soften and

hli>ter. r.se only the U'st spar rarni.ili, such as is matle for vannsh-

ing the spars of yachts; fill the woo<| with it; sandpa|H-r lightly

iM'tween coats, just enough s«i that each sutvct-tling ctiat will take

hold well ; fitiish with a coat well (lowed on; and leave it with it.s

natural gloss, whi<'h is more ladling than a nihU-il surface. This is

the treatnn-nt for hand-ntils. outside d*Mirs, inside hlintls, window-

.sills and jamhs, and everything «'X|)os»'«||i> the din-et sun. Hand-

rails and outside d(M)rs should he refinisln-tl everv vear; vaniish will

347

20 PAINTING

not last on an outside door more than one-twentieth as long as it will

on an inside door. Never use interior varnish for outside work.

ENAMEL PAINTS

Varnishes are all more or less brownish yellow or yellowish brown.

Therefore a coat of varnish applied over a paint obscures and changesits color to some extent. To overcome this as much as possible, the

varnish, instead of oil, is mixed with the pigment, as a vehicle. In

this way the pigment comes to the surface and displays its •color.

These paints, if made with good varnish, are durable; the method of

application has already been described. If necessary to thin them,do it with spar varnish instead of oil; a good interior varnish may be

used, but it injures the flowing quality of the paint somewhat.

White lead and zinc are sometimes mixed with damar varnish.

This makes the whitest enamel paint, but it never gets very hard,

never has much luster, and is not very durable. It is very white, is

easily applied, and dries quickly.

A NEW VARNISH FINISH

A method of finishing open-grained interior woodwork, which has

been practiced for a few years, consists in first staining the wood with a

water-stain—dyeing it, usually—and then, when it is dry, filling the

pores of the wood with a paste filler which has been colored by the

addition of a pigment. For example, the wood may receive a stain

of any dark color, and the wood-filler be mixed with white lead. This

shows the open or porous part of the grain in white on a dark back-

ground. By using artistic combinations of color in the stain and filler,

very beautiful effects can be produced, and this finish has been used in

some of the most handsome and costly public and private buildings.

Thus, if a room is to be decorated in green, the woodwork can be madeto harmonize with the prevailing color. An oil stain must not be used

on the wood, as it will not work well with the filler. The colored filler

is applied and rubbed off in the same way that any paste filler is used,

and then the varnish is applied over it in the usual way.

FLOOR FINISHING

The primary trouble with floors is that people walk on them. If

they did not, there would be no trouble at all. Four coats of varnish.

348

i'AlNTING 21

oi ... 11j.-iiiii, havinj; an aij;;;rf;^iitf tliiikm'.s.s of less than om* om*-

iuinilritlth uf an inch, will nut last indcliniti-ly under the \vi>ar uf nuil-

shcxl hfcls.

Pn)l>alj|y tin- siniplest treatnu'tit for Htjors is painting thenj. The

jKiintshoiilil contain a larj^e projjortion of a hard oleo-resinous

varnish; an ordinary oil paint is not hanl enough. If an oil [Kiint is

usihI, it must he heavily char{;e<l with dryer, for a floor [)aint should

dry in twelve hours. (Joofl (juiclvHlryinj; Hour jiaints are in the

niarki-t.

Fl(M>rs of ciioice wood, however, are not usually |Kiinte4l; they mayIh' either varnished or waxetl. If tlu-y areof oak or other o[X'n-^niine«l

woo«l, they nuist he lilled with a jjaste filler; otherwise the varnish is

aifplii-d directly to the wocmI. Floor varnish is <|uicker in drying, and

hardiT than interior finishing varnish, hut should not he so hanl as to

he hrittle; ruhhiu}]; varnish is too hanl. If the floor is to he staiue<l,

this is tlone with an oil stain hefore varnishin;^; if it is a floor which

has previously heen varnished, so that the stain will not penetrate the

wood, the stain may he mixed with the varnish, althoiij^h the effirt is

not then so good.

Floor wax is not made of heeswa-X, hut of a harder ve<:etal)le wax,

and is sold hy all paint ilealers. The Hoor should receive one coat of

shellac; then the fl(H)r wax may he ruhluHl on with a stiff hrush, and

when it is <lry, which will he in a few hours, it may he |)olishe«l hv

ruhhinj^ with a clean cicjth or with a heavy, wei<;hte<l floiu- hrush madefor the pur|M)se. It should receive another coat every week until f<»ur

or six coats have l)een a|)plied; after this a little of the floor wax,

thiinied if necessary with turpentine, should hi- applied often enou;;h

to keep the floor looking w<'ll. .Alkalies <lissoIve the wax, and in

cleaning the floor only a little soap should he usnl in the water with

which the flocjr is wa.shcd. A wax finish kept ]H>lished with a |N)lishing

hrush, is the handsomest surface than can h(« ohtainetl for a fliM»r; hut

it is so slipjMTy that it is somewhat dangerous. It d«)es not disct>lor

the w<kh|. Interior trim (hut not hand-mils) is .sometimes wux-

finishe<l. This finish re<|uires a gotnl deal of care, as it is likely to

catch dust; otherwise it is harnlsiime and durahle.

( )ld lliH)rs whichre<|uir»-

cli aiiing and revarnishing should have

the old varni.sh or paint removed hy u giMnl vanilnh-miiovrr, tme of the

niiNleni .sort, fre*- from alkali. This is{Miinttil over the surfac-e, and,

340

22 PAINTING

after a short time, removed with a scraper. The last of the varnish-

remover is taken out with a rag wet with turpentine or benzine, care

being taken that there is no fire of any sort in the room or any neighbor-

ing room. This will not only take off the old varnish, but the old filler

also; and the floor must be treated like a new floor. Any stains on the

floor may be treated with a hot solution of oxalic acid, one part to ten

of water; when the stains disappear, wash well with clear water; let

the floor dry a day; sandpaper; and it is ready for varnishing again.

This treatment—removal of old paint or varnish by a liquid varnish-

remover—is applicable to all varnished or painted work. The outside

of a house could have the old paint taken oft' in this way, but burning

off is cheaper and quicker. These varnish-removers are mixtures of

benzole, acetone, alcohol, and other liquids, and the best of them are

patented.

ALUMINUM AND BRONZE PAINTS

Radiators and pipes are often painted with aluminum or bronze

paints. These consist of metallic powders, in fine flakes, mixed with

some varnish—usually with a pyroxylin varnish, which is a thin solu-

tion of a variety of gun-cotton in a suitable solvent, generally acetate of

amyl. If one of these paints—which smell somewhat like bananas—

becomes thickened in the can by evaporation, it can usually be thinned

with acetate of amyl, if some of the special thinner cannot be had;

brushes can be washed out in the same. A good aluminum paint is

durable, even exposed to the weather. One coat is usually enough,

two certainly so.

GLAZING

House painters are usually expected to understand the art of

setting window-glass; it is not difficult to learn. Glass is classified as

sheet or cylinder glass and plate glass. Sheet glass is made, at the

glass works, by blowing a quantity of glass, first, into a hollow globe;

then, by more blowing and manipulation, this is stretched out into a

hollow cylinder perhaps a foot in diameter and five feet long; this

cylinder (whence the name "cylinder glass") is cut open, and, after

reheating, is fiattened out into a sheet, whence the name "sheet glass;"

after annealing, it is cut up into convenient sizes. It is made of two

350

PAINTING 23

thicki.. ... ^.,iiifjlf thick, which is alxjiit oiu'-sixtii'iitli of an inch;

ami (Iniihlt thick, onc-cij^hth of an inch; l)Ut it (Iocs not nni [H*rfiftly

uniform. All sluft jjhiss contains .streaks, huhlilcs, and specks of

Wirt, and is more or less irre},'nhir or wavy in its surface; ami in n*s|>ect

to this it is "jradetl as first, second, and third ijuality; in American f^lass

these ^ades are usually marked "AA," "A," aiul "M;" and anylhin;^

p)on'r than "B" is called stock sheets. Forei^i glass is not thus

markitl, each maker having his own arbitrary marks. Single-tlnek

glass is usiMJ for sizes not greater than alxjut 2S hy 34 inches; double-

thick, up to 40 by <)(). For larger siz«'s, j)late glass only is us***!; but

of course either plate or double-thick can be use<l for small sizes, if

desireil.

Plate glass is cast in j)lates; the lifjuiil glass is [)oure<l out on an

iron table, about 1') feet wide and 2.") feet long, and sm(M»the<l down to a

uniform thickness of half or five-eighths of an inch by j)assing a roller

over it, like n)lling pie-crust; after this it is ground «lo\vn with sand,

emery, and polishing powder to a (piarter or five-sixteenths of an inch

in thickness. It is therefore nmch more costly than sheet glass, but

is also more perfjft.

Cr}'stal is a very thin plate glass, about one-<'ighth of an inch thick,

and is usctl where ordinary plate is too heavy, as in movable siish. It is

the finest of all window glass. There are two grades of plate gla.ss,

known as glazimj (for windows) and silverinr/ (for min-ors), the latter

being the best. In the first place, the sa.sh is prepannl for the glass.

It must receive a priming coat; if it is to be painte<l, it is primed with

white lead and boiled linseed oil, the mixture liaving very little or no

turjM-ntine adilcfl; if it is to be varnished, it is jjrimiil with Iniiled oil

al()ne. If it is not priine<l,the ])Utty

will not stick; the wimhI will draw

the oil out of the putty and Ic-ave it crumiily. Next, the glass is litte<l

to the sii.sh. It is cut either with a glass-cutter's diamontl or with a

wheel cutter, the latter being a little shar|w<lge«l steel whet'l set in a

handle. If well made, the wheels may be Ixjiight .sejmnite and are

replaceable. The wheel cutters are generally u.sed on .sheet gla.s,s; but

plate gla^s is cut only with a diamond, which makes a <lee|>er cut.

The wlui Is are kt'ptwet with kerosene; the workman has a little Ixttth-

or cup of kero.si-m* on the ImiicIi, and dips the wheel in it.

The glass being cut to the right size, a layer of putty is spnail,

with the putty-knife, along the recess in the .sash where the gla.ss is to

351

24 PAINTING

rest. This is called bedding the glass, and should always be done.

It is not uncommonly omitted with pine sash ;but it absolutely must be

done with all hardwood sash, metal or metal-lined sash, and for all

plate and crystal glass ;and it ought to be done in all cases. Then the

glass is gently pressed into place, after which it is fastened with glaziers'

'points, which are triangular bits of metal. No. 2 points are used on

single-thick, and No. 1, which are larger, are used on double-thick

glass; they are put in 9 to 12 inches apart. They are driven, not with

a hammer, but with the thin side of a two-inch chisel, the flat side of

which lies on the glass, the edge of the chisel away from the surface

so as to avoid scratching it. The chisel is also useful for adjusting the

position of the pane; if it is smaller than the sash, it is so placed that

when the sash is in its natural upright position the pane of glass will

rest with its lower edge bearing on the wood. The points are com-

monly of zinc, which bends easily; and when the pane is properly

placed, if there is on one side a space between it and the wood, the

chisel is held over this crack, and with its edge an indentation or crimpis made in the little triangular zinc point which has already been

driven; this crimp prevents the glass from sliding back against the

wood. This is the reason zinc is used for the points; it will bend.

Steel points are sometimes used for plate glass, because of their greater

strength, the glass being heavy. To drive through the sheet metal of

metal-covered sash, steel slugs are used ; these are about ^^g inch thick,

about I inch long, and -^^ inch wide at the wide end, triangular, and

sharp-pointed.

There is a machine for driving points, but it is not much used

except on small glass set in soft-wood sash.

The glass being properly secured by points, it is ready for putty-

ing. To do this, the professionals set the sash up in a nearly vertical

position on an easel; the glass is puttied on the right-hand side and

across the bottom; then the sash is turned the other edge up, and the

operation is repeated. This finishes the work.

The most important things about glazing are to use a sufficient

number of points and to use good putty. Ordinary (pure) putty is

made of whiting, which is pulverized chalk, mixed with enough linseed

oil to give it the consistence of stiff dough. The workman can make it

from these materials with his hands; everyone can make his own putty.As a matter of fact, however, the putty of commerce is made by ma-

552

I'MVnVG 25

fliiiurv; and also, us a matter of fact, it is in ^nieral uhominablyatlnltt-rattil. It Wdiiltl sofni as tlion^li wliitin^j and lirjsti-d oil were

inatiTials clu-ap t'liouj^li; and in reality [)Utty can Ik* sold for alnnit

three cents a {x^nnd, or sixty dollars a ton; and a dollar's worth will

pntty all the glass in an ordinary house. Pure putty, however, is

almost impossihle to get. Marhh- dnst is sul)stitute<l for whiting,

and a mixture of rf)sin and mineral oils for the oil, and the c<ist reducetl

alH)Ut half. It is the use of this miseraMe stuff which causes nine-

tenths of the tnmhles with windows. If the glazier cannot he sure of

his putty otherwise, he should make it himself.

The best putty for glazing is a mixture of pure whiting putty with

one-tenth white lead putty. This makes it set a little more <|uickly,

and it hecomes harder. Pure white lea<l j)Utty gets too hanl; it is too

dinicult to remove it in case of breakage of glass.

If the glass has not been biildeil in putty, it is customary to go

around the indoors side of the glass, and crowd st)me putty into the

crack between it and the sash. This is calle«l harkinr/ the glass. I^irge

plates of plate glass are not puttie<l, but are held in place with.strijis

of moulding nailed on the .siish, in which case the crack Ix'tween the

glass and the moulding is backed with putty.

053

REVIEW QUESTIONS.

PRACTICAL TEST QUESTIONS.

In the foregoing sections of this Cydo[>c«h'anumerous illustrative examples are worked out in

detail in order to show the application of the various

methods and principles. AccompanyiuR these are

examples for practice which will aiil the reader in

fixing the principles in mind.

In the following pages arc given a large numberof test questions and problems which afTortl a valu-

able means of testing the reader's knowledge of the

subjects treated. They will be found excellent prac-tice for those preparing for College, Civil Service, or

Engineer's License. In some cases numerical answers

are given as a further aid in this work.

ns5

R 1 : \ I !•: \v Q ('

1-: s i' i < > x st> N Till-: M I

•

1 1 .1 K 1 !• < » !•

KLKCT R I C W I K* I XO

1. Explain the tlirrc-\vin> .system of wiring.

2. Ill ca.sf a te.st .shows cxcT.ssivc lrakaf(f, or a j;rouiiil or .sliort

circuit, how wouM you locate the trouble and ren)e<ly it?

;}. Descrihe the construction aiu'l use (if outlet-lxjxes.

4. What is the principal ditlerence hetween alternating aniJ

(lirectK'urrent circuits, .so far as concerns the wiring system?

5. Compare the advantages of the two-wire and three-wire

systems of wiring.

(). I'nder wliat gi-neral heads are ajjjiroved methods of wiring

cla.ssified?

7. A single-phase induction motor is to he suj)plieil with 2o

amperes at 220 volts; alternations 12,()()() per minute; power factor. S.

The transfonner is 200 feet from the motor, the line consisting of

No. 1 wire, inches iK'tween centers of conthictors. The tnin.s-

fonner reduces in the ratio 2,.")()(), has a capacity of 30 amperes at 220'250

volts, and, when delivering this current and voltage, has a resistance-Iv

M. F. of 2. ') jxT cent, and a reactance K. M. F. i>f .'> per cent. Cal-

culate the drop. (I'.se table and chart.)

s. What are the distinctive features of the dilVcniit kinds of

natal conduit?

0. Suppo.se |)ower to l>e deliven-d, :{(M) K. W.; F. M. F. to Ih'

delivered, 2.2(M) volts; distance of transmi.ssion, !.').(H)0 feet; size of

wire, No. 00; distjina" Iwtween wires, 21 inches; |)ower factor of load.

.7; fre(|uency, KM) cycles [ht .second. Calctilat*- line lo.ss and «ln>p

injM-r

cent of \\. M. I', delivered. (I'.se table and chart.)

10. In installing A. ('. circuits, what r»'<|uin'ments an- insist«t|

on as to till- placing of contlui'tors in conduits?

11. I)«'S(Tilw the mainifactun-, use, ands|><'eial advantages of

the dilkrent kinds of armored cable.

.157

ELECTRIC WIRING

12. Describe three different methods of testing? Which is to

be preferred?

13. What conditions determine whether a two-wire or three-wire

system of wiring should be used?

14. In locating cut-out cabinets and distributing centers, what

requirements should be fulfilled?

15. What is "knob and tube" wiring? Explain its use and dis-

cuss its advantages or disadvantages.

16. How far apart should insulators be placed?

17. What tests should be made before an electric wiring equip-

ment is finally passed for acceptance? Give reasons.

18. What regulations govern the use of fibrous tubing?

19. What is meant by mutual induction?

20. What are the advantages and disadvantages of overhead

linework as compared with underground linework?

21. Describe and illustrate by sketches proper methods of

supporting and protecting conductors.

22. Discuss the advantages of running conductors exposed on

insulators.

23. Illustrate by diagram, proper and improper methods of

grouping conductors of two two-wire circuits.

24. What dangers are inherent in the use of moulding? What

precautions should be taken to avoid them?

25. Describe the proper methods of laying out branch circuits,

(a) in fireproof buildings; (b) in wooden frame buildings. Give

sketches.

26. What methods of installing wiring are best adapted for the

following classes of buildings, (a) fireproof structures; (b) mills,

factories, etc.; (c) finished buildings; (d) wooden frame buildings?

27. What is skin effect? Its bearing on the problem of wiring?

28. In selecting runways for mains and feeders, what pre-

cautions should be taken?

358

REVIKW QUKSTIONS

ov TTXta HcrnJiocx ok

ELKCTRIC etc: ir I'TXG.

1. State the current, voltage, candle-jxnvi-r,

and efficiency ot

the incandescent lanip most conunonly used.

2. AVhat do von understand by the '• sinasliinir point "if

3. (live the main points of diU'erence hetween the thri-t

forms of arc lamp mechanism.

4. ^[ention the three principal parts i»f the Nernst lamp.5. Describe with sketch the anti-j)arallel systeni of fcedin<;.

G. Prove the law that illumination varies inversely with the

square of the distance.

7, AVhy is arc li«^ht photometrv a mon- ditli^Milt problemthan incandescent '

>5, Calculate the illumination three feet above the floor at

the center of a room IS feet square and 12 feet hi«;h. lif^hted byfour lO-candle-power lamps !• feet above the floor at the center of

the side walls, assumini; the coetlicient of retlection to be .'o .

It. What material is used for the tilanient of incandescent

lamj)s? K.xplain why.10. From the curve given in Fig. 4, ilelermine the etlicieiicy

V Jiich coire.-iponds

to the tt-mjK'rature of 1 ;}()() C"entign»de.

11. W'liat is the olijeci of ilouble carbons in an arc lamp?I'l. What is meant by mean sjtherical candle-power?):!. What is the function of the heater in the Xernst lamp?1 I. l)escril»e the liunsen IMiotonieter.

IT). lii)wdt>ert the lighting of public halls dilTer from that of

residencuri ?

IG. Why cannot platinum wire be used for tlu< tilament uf

incandenCM'nl lamps {

300

ELECTRIC LIGHTING

17. In a direct-current arc lamp, which carbon bu) ns awaythe more rapidly ?

18. How are arc lamps rated ?

19. What are the important advantages of the two-wire

parallel system of distribution ?

20. Name and describe the most desirable standard for pho-tometric measurements.

21. How many measurements should be taken in the deter-

mination of spherical intensity ?

22. What is meant by flashing? Explain.

23. Define emissivity.

24. If the voltage of an incandescent lamp be increased 4%above normal, what is the effect on the candle-power, efficiency

and light?

25. Explain the Cooper-Hewitt lamp, stating the two

methods of starting.

2G. Compare the open and enclosed arc lamps.27. Why is the positive carbon placed above the negative in

a direct-current arc lamp?28. Sketch and name the different forms of incandescenf

lamp filaments.

29. Under what conditions can a 3.1-watt incandescent lampbe used ?

30. What is the function of the arc lamp mechanism?

31. What are the advantages of the three-wire system ?

32. Why is it necessary to exhaust the bulb of an incandes-

cent lamp?33. At what point in their life should incandescent lamps

be replaced ?

34. What is the object of a resistance in series with the arc

lamp in constant-potential direct-current systems?35. Name the advantages of the Nernst lamp.3G. What sort of lamps and of what candle-power should be

used in residence lighting ?

37. Give the characteristics of the Cooper-Hewitt lamp.38. What M'ill be the external resistance on a 110 volt con-

stant-potential system, if the load consists of 437 lamps of 16

candle-power ?

360

K K V I !•: W (J I

•

!: S T I (> X s

ON 'r II K MlTlUKi'T CK

PLASTKRINCi

1. I)f>(ril)c the prDpcr int'tlnMl ofspaciii;,', iiailiii;:, ami joining

wood lath.

2. Of what materials is mortar comixjsttr;:'\Vliat are the

retjuirements of each to insure gmxl results?

3. Compare the relative advantages of metal and wcmkI lathing

for both interior and exterior plastering.

•1. How are estimates for lathing and plastering made?

o. ^Vhat precautions are absolutely necessarv in the i)lacing

of metal lath?

(). If wood lathing is used on exterior work, how should it be

laid?

7. When, if ever, is wire lath preferable to expanded metal?

8. Describe in detail the process of slaking the lime and

mixing the mortar for ordinary interior plaster work in dwelling-

houses. What precautions are to be ()b.ser\'txl?

0. ."Should mortar be used as soon as mixed? Di.scuss this

question in all its b«arings.

10. How would you mix the mortar for e.xttrior work?

11. If lime is not thoroughly slaked, what trouble is likely to

develop?

!_'. What will b<- the etlect of u.siug too much lime in mixing

njortar? too much siind?

i:!. What are the e.s.sentials for «lurable exterior plastering?

1 1. l)i.scu.s.s th«' relative advantages of three-cojit an«l fwiwojit

work. In what kind of work are three coats always nece.vijiry?

I.". In interior work, what precautions must U- observetl in

laying the .succe.s,sivc coats of plaster? In exterior work?

an 1

REVIET\^ QUESTIONSON THE SUBJECT OF

PAINTING

1. Wliat is the difference between raw and boiled oil? \^lien

is one preferable to the other?

2. What would you consider a good brush outfit for painting

and varnishing the interior woodwork and exterior finish of a modern

frame dwelling?

3. How would you make your own putty if you could not buya satisfactory grade?

4. Describe the princii)al ingredients used as figments. As

vehicles.

5. What are thinnersf Dryers? Fillersf

6. How are painters' brushes kept in good condition?

7. How are paints adulterated?

8. Describe the process of mixing the successive coats of

paint for ordinary interior (not floor) and exterior woodwork.

9. Describe the process of preparing the woodwork and

applying the successive coats of paint in ordinary interior (not floor)

and exterior work.

10. What points require particular attention in the repaintingof an old job?

11. Describe the process of painting a plastered wall.

12. Describe the material and methods of work in roof painting.

13. What is enamel paint? How would you do a job of

enameling the woodwork, say, in a bathroom?

14. Describe in detail the process of painting structural metal.

15. How are varnishes classified?

16. Describe the method of preparing and applying shellac

varnisn.

362

INDEX

The page numbers of Ihia vulumt will be juaud al the buUum uj the

pages; the numbers at the top refer only to the aectton.

Page

Altcrnatlng-curreni clrcuiw

INDEX

Page PageD

INDEX

1 li'iiii III t II 'II

rcKular rpfl«>rtlon

unit of

liu'anilcM'i'iii laiii|>->

urruiiK«'n>fnt of lani|M

csrboa

i-omparlson of dIfTcrpnt types of

tlbirihiitliin of IIkIh

i-flUiency of

Intfiuilty fon.stant.s fur

tyiH*. compurt-ain of

MiltiiKo and caiMlU'iHiwfT

Insulators. »ir<f> run fX|KJM-<l on

lnt<-n.->ity ron-stant^

InttTfhanBcable arc

Interior pla-stcrinR

Intrin.sir l>ri|{litnr!vs

Irrrgular reflection

aK<-

INDEX

Plastering

plaster molding

rough finish

scratch coat

three-coat work

two-coat work

PolesI'

Polyphase circmts

Porcelain insulator

Power distribution

R

RakinK moldings

Rating of arc lamps

Reactance e.m.f.

Reactance volts

Residence lighting

calculation of illumination

plan of illumination

type of lamps

Resistance e.m.f.

Resistance volts

Rigid conduit, wires run in

Roman moldings

Roof mensuration

flat roof

hipped roof

Roofing

corrugated iron

flat-seam

metal

soldering

standing-seam

tables

tools required

S

Sand

Scratch coat

Series distribution system

Sheet-metal skyUght

Sheet-metal work

cornice work

curved moldings

miter cutting

rooflng

skylight work

Page

320

312

311

310

313

80

63

27

140

228

114

55

55

150

150

150

55

55

11

234

193

194

195

188

212

197

192

202

207

189-191

193

302

311

140

163

163-294

225

281

236

188

163

Single-pitch skylight

Skin effect

Skylight work

bars, various shapes of

construction

curbs, various shapes of

patterns

shop tools

Skylights

double-pitch

flat extension

hipped

single-pitch

Slaking of lime

Soldering joints

Special lamps

mercury vapor

Moore tube

Standing-seam rooflng

Steel armored cable

Switchboard

Page171

52

163

166

163

167

166

166

171

172

172

173

171

303

85

121

121

123

207

16

65

Table

arc lamps, lighting data for 160

armored conductors 18

conductors, sizes of in fibrous conduit 25

conduit

single wire in 12

three wires in one 13

two wires in one 13

Cooper-Hewitt lamps 159

corrugated sheets, measurements of 214

drop in a.c. Unes, data for calculating 57

enclosed arcs, rating of 134

flaming arc data 140

flat-seam rooflng 189

gem metallized filament lamp data 106

Greenfleld flexible steel conduit 15

intrinsic brilliancies in candlepower

per square inch 148

life of a 25-candlepower unit data 110

Meridian lamps. Illuminating data for 156

metals, meltlnt; pfiint of 115

moldings, sizes of, required for vari-

ous sizes of conductors 22

Moore tube light data 126

Note.—For page numbers see fool of pages.

866

INDKX

Pagp PiM(«-

Tubl.

N>rii>i lumii iliita

IMili- (lattt

ri-UwllnK power. n-Iatlvo

rcHldi'ntv liKlitliiK (lata

tIkUI t'liuiiii'ltxl i-iin<lult (lata

rdoHoK. MtanUliiK-M-ain

Nkin cfTcct, (lata for cakrulatliiK

tantalum lamp data

I in (ilutc (lutu

tunK-<t<'n lamp data

VDltaKt*. firects of clianKi! In

Tantalum lampTcrno plate r<Kj(lnK

TcsitInK clertrlc wiring

Threo-wiro system, electric wiring

TunKstcn lamp

Turret Nash

Two-wire, electric wiring

V'oltaKe and candlepower

Voltmeter

WWater-tlKlit outlet box

Wires run concealed In conduits

armored cable

flexible metal conduit

Nnie.—For page numbers see foot of pages.

683017

.f.

Cyclopedia of Architecture Carpentry & Building Vol IX

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