Electrical Experimenter191712

7 miz-kl'ior' ff\ Ir K rkCO when you finlth reading thl magiulne place a 1 cent (tamp on thi notice, hand same to any postal employee and it will be

I Tell YouB^ i success and command big pay. You caneasily do it if you will only prepare yourself/ \Vhy-liill men neglect to prepare themselves, when trained

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And remember, T give every student a GUARANTEE BOND which insures you sat-isfaction or everv dollar of vour money refunded. I can make such a guarantee becauseI know my Course and what it does for my students, .ênd for free illustrated book telling all about it.P.\RT OF YOUR SPARE TIME devoted to this interesting work is all that is needed. You will findit most fascinating, and in a short time your earning power will be greatly increased.

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December, 1917 THE ELECTRICAL EXPERIMENTER 505

CHEMCRAFT No. I Price Delivered $1.25West of the Mississippi and Canada $1.50

This Is a dandy sci ui a very n-asiuiiililc price.Willi it yciii can work lots of wonderful experimentscat'li one cjI ulncli can bo rciu'mud many tunes.'J'ht-re are 14 flil^^'^^llt Chemicals, lest tubes, elasatube, iiien-siirL's. fic., tutjelher wltJi the No. 1Chinii-rntt \uuiU xiliich uives coniplclo dircctionH.exjilaiiii^ all Iho experiments In a clear, interestingniainier. and tells many wonderful and InterestingIhiniis about Clieniifiry.With Chemcraft No. 1 you can inalie flro Ink and

Here is your opportunity to learn about the wonderful science of chem-istry. Chemcraft gives you the most fun, the most experiments and themost real knowledge.Chemcraft service and asubscription to the Chem-craft Chemist are freeto Chemcraft owners.

CHEMCRAFT No, 2Price Delivered J2.50

Weit of the Mluitilpoi and Canada $3.00Chemrraft No. 2 Is iiiurh lardt-r lli:in tin- Sn. 1

ect. ll ..jhuiits o:i dlircrt'iil rin'im-als and a lib*fral assurliiiL'iu or Aiii-aratUM and cuulpiiiunt.lluro arc many rare and valuable Chonilcala In-cluilud In Una oulllt winch rt-prfsonu Uie blKai.'jilvalur t'viT put on inarkt't for such a low price.The In.struclion book which coniea with this wtKiies dirccii.jns for working nearly a hundred won-derful experlnienla and after jou liave used theset for a little while you will be able to ilovUetouiitle.ss athlitinnal cxpcrinienls of your own

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506 THE ELECTRICAL EXPERIMENTER December, 1917

ElectricColumbiaGrafonolas

at n35/145, nSS and *240

'T^HE first time you hear an electric--*- ally equipped Columbia you will

want to own one.

The electric motor, which is a marvel ofsilence and smoothness, holds the mellowbut brilliant Columbia tone absolutelytrue.

It operates perfectly on any standarddirect or alternating current. Just at-

tach plug to socket.

A beautiful Columbia Electric Grafo-nola is just as much a part of the modernhome as a beautiful electric lamp.You can purchase a Columbia ElectricGrafonola 125 E for as little as $135.The same model equipped with Colum-bia Individual Record Ejector

price

$145-Step into any store where ColumbiaGrafonolas are sold and listen to theColumbia Electric Grafonola. You andthe Columbia Electric Grafonola willquickly become friends.

Columbia Graphophone CompanyNew York

X .itAe

Columbia ElectricGrafonola 225 E

Price $240Cabinet of mahogany, satinwalnut, or quartered oak inall finishes, measuring 49jiinches high on castors, and2254 X 24 inches. All ex-posed metal parts heavilyplated in 18 karat gold.Ample record storage room.

You benefit by mentioning "The Electrical Experimenter" when tvriling to advertisers.

Tlbe Electrical rimeeter233 FULTON STREET, NEW YORK

Publisht by Experimenter Publishing Company, Inc. (H. Gernsback, President; S. Gernsback. Treasurer;) 233 Fulton Street. New York

Vol. V Whole No. 56 DECEMBER, 1917 No. 8DAYLIGHT SIGNALING WITH SEARCHLIGHT Front Cover

From a painting by George WallLOCATING THE SUBMARINE BY RADIO. .By H. Winfield Secor 509ELECTRIC BOMB DROPPER FOR AEROPLANES SURADIUM PAINT IN THE WAR 512ELECTRIC XMAS TOYS 513DAYLIGHT SIGNALING WITH ELECTRIC SEARCHLIGHT... 514THE MARVELS OF RADIOACTIVITY. PART IV

By Jerome S. Marcus, B.Sc. (Ch.E.) 515HOW I TELEGRAPH PICTURES By J. H. Leishman 516ELECTRICITY AND GOLD FISHES By H. Gernsback 518WOMEN MAKE GOOD RADIO OPERATORS 519A TRACKLESS TROLLEY SYSTEM By L. Schoolcraft 522THE SUBMARINE AND KINDRED PROBLEMS 524A NEW COMBINED STEREOSCOPIC AND FLUOROSCOPIC

TABLE 525MAGNETIC SEPARATOR PULLEY GREAT TIME SAVER....

By F. C. Perkins 526A REVOLVING ELECTRIC XMAS TREE By John T. Dwyer 529

HOW TO USE HIGH FREQUENCY CURRENTS IN THE TREAT-MENT OF DISEASE By Dr. Frederick Finch Strong 530

THE "RADIO ROLL OF HONOR" 533SOME INTERESTING NEW RADIO APPARATUS 534THE AUDION AND THE "EDISON EFFECT". .By George Holmes 536RADIO TRANSMITTING INDUCTANCES. PART VTHEHOW AND WHY OF RADIO APPARATUS 537THE UNCROWNING OF THE GIMCRACK KING

By Thomas Reed 539THE MYSTERIOUS VOICE By C. A. Oldroyd 541AN ELECTRICALLY PLAYED MANDOLINHOW TO MAKE

IT By McClure Albright 542AN AUTOMATIC STORAGE BATTERY CHARGER

By Lewis Scriven 544HOW-TO-MAKE IT DEPT.PRIZE CONTEST 547WRINKLKS, RECIPES AND FORMULAS. .Edited by S. Gernsback 549EXPERIMENTAL CHEMISTRY19th Lesson

By Albert W. Wilsdon 550"ELECTRICAL LABORATORY"Prize Contest 551LATEST P.^TENTS DIGEST 552PHONEY PATENTSCONTEST . ^ 553QUESTION BOX 554

SOLAR "HEAT"E may take it as an established fact that

sun is a huge ball of incandescentmatter. Spectral analysis shows that thesun contains every element known to usas found on the earth. Every metal, everygas is represented in the incandescent

plioto-sphere, i.e., the gaseous envelope surrounding thesun, burning at a tremendous heat.We know the sun to be some 93 million miles distant

from the earth. Enormous as this distance isincom-prehensible to the human mindwe receive daily fromour luminary a quantity of energy nothing short ofastounding. Only by remembering that a light-raytraveling at a speed of close to 186,000 miles per second,requires a little over 8 minutes to traverse the gulfseparating the sun from the earth, do we begin torealize what sort of a problem we face, when we wishto make it clear to our minds how such a stupendousenergy, which lights and heats our planet, is conveyedto us thru a vacuum. For the odd 93 million milesseparating the sun from the earth constitute of coursean almost perfect vacuum. Nevertheless the earth islighted and heated. But how does it come about?Now we know that if we go only 30 miles above the

surface of the earth, we strike a temperature of 273degrees Centigrade, the absolute zero of interstellar space.Nevertheless, heat in some form gets thru this tremendouscold, paradoxical as this sounds at first. Otherwise,how do we account for the earth being heated by thesun? If you doubt that it gets colder as you go up,you have but to climb a mountain of moderate height.Even three miles up the cold becomes so intense thatthe top of the mountain will be found covered withperpetual ice. Notwithstanding this, we are closer tothe sun by 3 miles at the summit than at the base ofthe mountain ! Also we find by way of further proofthat if we expose a thermometer directly to the sun'srays at the top of the mountain, the temperature willbe about the same as that of the ice at our feet. Andit makes little difference if we perform this experi-ment on an ice covered mountain at the equator.

or on a similar mountain in more northern latitudes.Logically then we are forced to the conclusion that

we do not receive heat rays from the sun at all. Forthe dark heat rays can not pass thru a vacuum. Byplacing a thermometer in an ordinary Thermos bottlethis statement can be verified readily.But where does the heat come from? How is the

earth heated after all, for heated it certainly is?By the sun's light rays. We know these rays not to

be merely luminous rays, but they are in reality electro-magnetic rays. Now then, when these cold rays strikethe earth's atmosphere at its lower strata, where thelatter is heavily comprest. to some 15 lbs., per squareinch, these cold light rays seem to undergo a trans-formation, and in the act greatly heat the surroundingair. Just what this transformation is we do not as yetknow, mainly because we do not actually know the truecomposition of a light ray. We don't know what liesbeyond the ultra violet, nor the ultra red section of thesun's spectrum. Nor do we know much of the lightrays' electrical structure.

At this point we wish to make an interesting reflec-tion. Not so long ago the famous Dutch philosopherDr. Kamerlingh Onnes made certain experiments oftremendous import. He placed an electrical conductorin an almost absolute zero, and found to his astonish-ment that a current started in such a conductor wouldcontinue to flow for 19 hours. The tremendous cold robbedthe conductor of all its former resistance, and theelectric current finding no resistance to wear itself outin heat, became a sort of perpetual circuit, which lastedas long as the conductor was near the absolute zero.Now the point is, the space separating the earth from

the sun is at an absolute zero. Is this not perhaps thereason that the sun's light-rays which are of courseelectrical in natureact in a like manner to the elec-tric current in Dr. Onnes' experiments? This thenwould explain, why practically no energy is lost in thetransmission thru 93 million miles of icy space.

H. Gernsback.

THE ELECTRICAL EXPERIMENTER In publlstat on the IStb of each month at 233Fulton Btreet. New York. There are 12 numbers t)er year. SubacrlptloL price is $1.50 arear In U. S. and posseaslona Canada and forelKn countries. $2.00 a year. U. 8. eolnas well as U. S. stamps accepted (no foreUn coins or stamps). Single copies. 15 centseaob. sample copy will be sent gratis on request. Checka and monm orders should bedrawn to ordtr of Tin: EXl'SmlMENTEB PnBLISHINQ CO., LNC. If you change youraddress notify us promptly, In order that copies are not miscarried or losL A graenwrapper Indicates expiration. No coplea sent after expiration.

All communications and contributions to this Joursal should b6 addreat to: Editor,THE ElJiCTBIOAL EXl'EBIMENTEB. 233 Fultm Street, New Tork. Dnaoceptod con-

tributions cannot be returned tmless full postage has been Included. ALL acceptedcontributions are paid for on publlcaUoo. A special rate Is paid for novel experlmenta-good photographs accompanying them are highly desirable.THE EIJ:CTR1CAL EXPERrMEXTER. Monthly. EntM-ed u second-clasa matter at

the New York Poet Offlce. under Act of Congress of Uarch 3. 1879. Title registered U SPatent Offlce. Copyright. ISIT, by R P. Co.. Inc.. New York. Tha contents of thismagazine are copyrighted and must not be reproduced without giving full credit to thepublication,THE ELECTRICAL EXl'ERIMBNTER Is for sale at aU newsstands In the United Statesand Canada; aUo at Brentano's 37 Avenue da I'Opera. Parla. vi

508

II

THE ELECTRICAL EXPERIMENTER

iiiniiiiniiiiiiiiiiiaiiiiiBiiiiiiiiiuiiiiiiaiiiiiBiiiiiiiiiiaiiiiiaiiiiiiiiiuiiiBiiiiBiiii

December, 1917

iiiiiiaiiiiiaiiiiniiiiiaiiiiiHiHii

^^

The Boy*s Electric ToysThere have been other electrical experimental outfits on the market thus far, but we do not believe

that there has ever been produced anything that comes anywhere near approaching the new experimental

outfit which we illustrate herewith."The Boy's Electric Toys" is unique in the history of electrical experimental apparatus, as in the

small box which we offer enough material is contained TO MAKE AND COMPLETE OVERTWENTY-FIVE DIFFERENT ELECTRICAL APPARATUS without any other tools, except a

screw-driver furnished with the outfit. The box constructionalone is quite novel, inasmuch as every piece fits into a specialcompartment, thereby inducing the young experimenter to beneat and to put the things back from where he took them. Thebox contains the following complete instruments and apparatuswhich are already assembled

:

Student's chromic plunge battery,compass-galvanometer, solenoid, tele-phone receiver, electric lamp. Enoughvarious parts, wire, etc., are furnishedto make the following apparatus

:

Electromagnet, electric cannon, magneticpictures, dancing spiral, electric hammer,galvanometer, voltmeter, hook for telephonereceiver, condenser, sensitive microphone,short distance wireless telephone, test stor-age battery, shocking coil, complete tele-graph set, electric riveting machine, elec-tric buzzer, dancing fishes, singing tele-phone, mysterious dancing man, electricjumping jack, magnetic geometric figures,rheostat, erratic pendulum, electric butter-fly, thermo electric motor, visual telegraph,etc., etc.

This does not by any means exhaust the list, buta great many more apparatus can be built actuallyand effectually.

With the instruction book which we furnish, onehundred experiments that can be made with thisoutfit are listed, nearly all of these being illustratedwith superb illustrations. We lay particular stresson the fact that no other materials, goods or suppliesare necessary to perform any of the one hundredexperiments or to make any of the 25 apparatus.Everything can be constructed and accomplished bymeans of this outfit, two hands, and a screw-driver.Moreover this is the only outfit on the market to-dayin which there is included a complete chromic acidplunge battery, with which each and everyone of theexperiments can be performed. No other source ofcurrent is necessary.

Moreover, the outfit has complete wooden baseswith drilled holes in their proper places, so that allyou have to do is to mount the various pieces bymeans of the machine screws furnished with the set.

The outfit contains 114 separate pieces of mate-rial and 24 pieces of finished articles ready to useat once.

The box alone is a masterpiece of work on accountof its various ingenious compartments, wherein everypiece of apparatus fits.

Among the

No. EX2002

finished mate-rial the follow-ing parts areincluded:

Chromic salts for battery, lamp socket, bottle of mercury, core wire (two diffn-ent lengths) , abottle of iron filings, three spools of wire, carbons, a quantity of machine screws flexible cord, twowood bases, glass plate, paraffine paper, binding posts, screw-driver, etc etc. The instruction bookis so clear that anyone can make the apparatus without trouble, and besides a section of the instruc-tion book is taken up with the fundamentals of electricity to acquaint the layman with all importantfacts in electricity in a simple manner. , .

, , , , t /: , .i. edia No. 19 measures 7 z 5^". ^HWeight % lb. Beautiful stiff covers. ^HNow before you turn this page write ^^

your name and address on margin b-low, cut or tear out. enclose 6 da.stamps to cover mall charges, and theCyclopedia Is yours by return mall.

THE ELECTRO IMPORTING CO.

231 Fullon Stieel. New York Cily

ELECTRO IMPORTING CO., 231 Fulton St.,N.Y.iiamiiBoiiiHiBiiiiiiHiiiii

I

JHE ELDCTRICRLEXPERIM BITER

H. GERMSBP^CK editc7RH. W. 5E^17R /qssDcmjE editor

Vol. V. Whole No. 56 December, 1917 Number 8

Locating The Submarine by RadioBy H. WINFIELD SECOR

WjriLF, there have been hundredsof schemes proposed in the pastfew months, for the detection anddestruction of submarine war-craft, there have been but very

few really practical suggestions in the totalnumber.The present discussion deals with a new

wireless scheme for detecting the presenceof submarines as far as two miles awayfrom a given base, which may be either on

worthless. At the present time very favor-able results are being obtained with micro-phones for this purpose, but severalproblems have yet to be solved in orderthat these sound-sensitive devices will per-form their functions under water properlyin order to accurately spot the "Hun" inhis stealthy U-Boat.Among the different forms of sub-

aqueous microphones devised by this in-ventor is one mounted in a special resilient

taking place will be gleaned from the ac-companying illustration. A vessel is hereshown radiating a wireless wave of saythree thousand meters length, which isequivalent roughly to two miles. Also forthe purpose of bringing out the efficiencyof the scheme more fully, two submarinesare shown and also their effect upon theradiating wave from the antenna.The inventor of this means of detecting

enemv sub-sea boats, received his first

SUBn/lglNE-J

WAVE. DISrOHTEDBY CP/ICITYEFFECT

SUBnfiHINE- Z OF SUBM/mif^E

This Radio Wave Method of Detecting and Locating Submarines and Even "Torpedoes" Has Been Tested Out and Gives Surprising Re-sults. It Is Effective up to Two Miles and More and the Enemy Cannot Evade Its Action, so Long as "Subs" Are Made of Metal.

a ship or on land. Credit for this submarinedetector is due to Mr. Leon W. Bishop,tvho is now associated with a staff of ex-perts engaged in solving military and navalproblems. Mr. Bishop invented the well-known multi-audi-phone radio and tele-phone amplifier.

Mr. Bishop has done a great deal of ex-perimenting with microphones for the de-tection of submarines and has evolved anumber of verj' ingenious and advancedtypes of microphones, especially suited tothese requirements, and for which purposethe ordinary microphone is practically

substance so as to keep it free from or-dinary vibrations and noises. Particularlyhas he devised special circuits for usingmicrophones in this work whereby theyare electrically balanced. He is also ex-perimenting with microphones which pro-duce direct current pulsations, thus con-ducing to the elimination of externalnoises.

Coming now to the wireless scheme forthe detection of submarines, whether sub-merged or not, over ranges of two milesand more, (depending upon the wavelength used), the general idea of the action

509

demonstration of the ultra-sensitive elec-trical action involved while operating an

undamped Audion receiving set somemonths ago, and which effect is quite wellknown.

It was found that when the Audionreceptor was suitably tuned, so as to pro-

duce a regenerative effect, i.e., producingradio frequency oscillations, that at certain

times a peculiar sound effect could benoticed in the telephone receivers connectedto the circuit. For sometime this changein the circuit, as manifested by the soundin the telephone receivers, remained an un-


ELECTRIC PLOWING IN GER-MANY.

The German fanners, being very hardprest in tilhng large tracts of land withan heretofore unknown shortage of labor,have made extensive use of large electricplows and other agricultural machines, oneof these immenseplows being shownhere.

Electrically oper-ated agricultural ma-chines of this typehave been used fora number of yearson German farms,the electric lightcompanies distribut-ing current for thepurpose over veryextensive areas, thecurrent being trans-mitted at very highpotentials, often inthe neighborhood of70,000 to 100,000volts for distancesof 75 to 100 milesand more.In some cases cur-

rent is supplied toeach individual ma-chine by means oftrolley poles, whichmake contact withtrolley wires sup-ported above thefield under cultiva-tion. In the instal-lation here illus-trated, current istaken from two trolley wires supported buta short distance above the ground, thesewires being moved along as the plow startsoff on each new run.Two specially designed trolley wheels

carried on an extension arm at the side ofthe plow conduct the current from the trol-ley wires to the electric motor on the plow.The plow is under perfect control of the

operator at all times, and this control iseffected thru the means of a drum con-

troller, similar to those used on trolley carsand small electric locomotives. These con-trollers, of which there are two, can easilybe seen in the photograph here reproduced.

This particular machine possesses severalnovel and unusual features, one ofwhich is the fact that at the end of one

Probably there is no country in the worldin which vast numbers of gigantic machineshave been so extensively applied for cul-tivating and harvesting crops as in thewestern part of the United States, but in theapplication of electrically-driven machinesfor accomplishing farm labors on a titanic

scale, the Teutonshave far out-dis-tanced other coun-tries.

Photo cour-tesy Society for Elec-trical Development.

The Teuton Tillers ofWhich Is lllustra

the Soil Make Extensive Use of Electrically Operated Plows, One ofted Above. Current Is Supplied the Motor Thru a Trolley Wire.

run across the field, during which it cutsseveral furrows, the machine is simply tilt-ed up with the main axle as the center, andthe operator then walks to the other end ofthe plow and controls it on the return runfrom that end of the machine. This over-comes the problem of having to turn thecumbersome machine around each time.Two manual as well as electrical con-

trollers are provided for this purpose, oneset at each end of the plow.

RADIO STA-TION FORHONGKONGOBSERVA-TORY.

A receiving in-stallation for theradio station. RoyalObservatory, Hong-kong, is now beingconstructed. Thestation is located atthe observatory, inlatitude 22 18' 13"N., longitude 11410' 15" E., of Green-wich. The installa-tion consists of asingle triangularsteel-lattice mast 150feet high. The aerial(which is on orderin America) willspread from themast to six chimneystacks of a terraceof houses ISO yards

to the south of the mast. The receivingapparatus consists of a receiving set to beused in conjunction with a Brown relay andhigh-resistance telephones.At present the installation is to be used

only for receiving time signals from Shang-hai, Manila, and Hanoi, and possibly fromTsingtau and one or more Japanese stationsby night. After the war it is proposed toinstall apparatus for distributing time sig-nals via Cape d'Aguilar radio station.

solved problem, but by careful observationit was ascertained that this was due to theeffect of a passing railroad train at a dis-tance of about one quarter of a mile. Therailroad tracks did not approach the build-ing in which the wireless receptor waslocated, and therefore it was decided uponthat the capacity effect of the steel railroadtrain on the wave radiated by the antenna,was sufficient to change this wave in sucha manner that the change could be readilynoted in the translating apparatus, vis., thetelephone receivers in this case.By looking at the accompanying illustra-

tion it will be seen how the presence of asubmarine, whether submerged or not, willcause a reaction on the radiated wave froman antenna located on a ship or on shore.Mr. Bishop has actually tried this out

successfully over considerable distances,and has found that it is possible to detectthe presence of not only a submarine a mileor so away, but even the presence of atorpedo; so ultra-sensitive is this methodof locating a metallic body.

Moreover, the direction in which themetallic body lies may be ascertained by theuse of a directional antenna, in somewhatthe same manner as the wireless compassscheme.This effect of bringing any form of

capacity in proximity to an oscillatingAudion circuit is well-known to most everj'radio experimenter. Those possessing os-cillating Audion sets have found invariablythat all of the circuits associated with thisdevice are extremely sensitive to such ef-fects. Even an approach of the operator'sbody, or for that matter his hand, towardthe apparatus upsets the electro-staticbalance of the circuits. Some of the setsused have proven so sensitive in this respectthat it became absolutely necessary to at-tach long insulated extension handles,sometimes two feet long to the variouscondensers and timing switches, so as toeliminate as much as possible this untowardcapacity effect of the body.The accompanying diagram showing con-

nections of .A-udion oscillator circuits aswell as a third, or Audion detector circuit,suitably equipt with telephone receivers,gives an idea of the apparatus employed byAir. Bishop in some of his researches alongthis line. Assume for instance an Audionoscillator with its proper capacity and in-ductance circuits all connected to an an-tenna as shown. This causes' the antennato radiate radio-frequency waves of alength depending upon the capacity and in-ductance in the circuit.We may assume for example that the

circuit is tuned to radiate a wave of 3,000meters, or roughly two miles wave length,which gives a frequency of one hundredthousand cycles per second. Consider alsothat the second Audion oscillator circuit isset in operation in inductive relation to thefirst circuit, which is connected to the an-tenna. The second or inductively associated-Audion oscillator is tuned to the samefrequency or one hundred thousand persecond. Further we note that there is athird coil inductively related to the oscil-lating circuits and which connects to theAudion detector and a pair of sensitive,radio telephone receivers.Now, if a submarine lies within detect-

ing range, say a mile away, and the an-tenna is excited by the Audion oscillatorNo. 1 with a wave having a periodicity ofone hundred thousand cycles per second,then its frequency will be slightly changedby the capacity effect of the submarine.Suppose it causes the oscillation frequencyof the antenna svstem to change from100,000 cycles to 101,000 cycles. If suchshould be the case, then there will be pro-duced a beat frequency note in the thirdor detector circuit, having a periodicity ofone thousand cycles per second, which is ofcourse an audible frequency, and therefore

(Continued on page 572)

BACK NUMBERS!Many readers desire to obtain back numbers of this journal. We have a limited quantity of these back Issues onhand and can supply them at the following rates:Back numbers of The Electrical Experimenter not over three months old, 15 centseach; over three months old, 20 cents each; over one year old, 35 cents each.


New Electric Bomb Dropper for AeroplanesBOMB dropping from aeroplanes canonly be approximately accurate. It

can be made at least seventy-fiveper cent more etTicient by sightingand releasing the bomb by mechani-

cal means and eliminating guess-work, asthere is only one aviator out of five hun-dred that is really proficient in the workwithout some mechanical aid. One of the

slide is graduated into seconds. The avia-tor decides in what direction the wind isblowing and in order to ascertain the speedat which he is flying, he picks out some ob-ject on the ground, having first set hisslide at the altitude he is flying, taking asight along the hypothenuse formed by thetwo bars of the sight, and as soon as theobject comes in line he presses his "itoii

aviator to discern his object at all.A Yankee genius, Mr. F. R. Lewis, has

overcome this deficiency by employing atelescope mounted on a tripod or base,swiveled and hinged to turn vertically orhorizontally, with quadrant and hand-screwto keep it in the desired position or angle.Figure 2. It is designed to have day lensesmade interchanireaMe with night lenses, each

i | fl e>'s P 8 i Q f! a5l Sig gj_gj

CFOURY/r,VS

SO/fS

BO/IBeficKINFUSELfiGC WITH

^^ I auTCHE5 IgJ

A Yankee Inventor Has Perfected the Simple Electric Bomb Dropper Here Illustrated for Use on Aircraft. The Aviator Checks up HisActual Flying Speed, Sets His Range-finding Telescope and Flies Over the Target. At the Proper Moment the Automatic Electric

Clock Switch Releases the Bomb.

best bomb sights in use by the Allies is theC. F. S. (Central Flying School) in theBritish service. The sighting is done overtwo bars arranged vertically, one abovethe other, about six inches apart. The thirdis fixt in a slide, level with the upper sight,thus forming a right angle triangle, withthe right angle forward and upward. The

watch, keeping the sight all the time on theobject he has selected, until it comes in linewith the two vertical bars of the sightHe then reads the time on his watch andadjusts his index slide to read that time.

But the great difficulty with this sightis that at a high altitude, or at night, it isvery difi'icult or nearly impossible for the

provided with cross-hairs, and external lo-cating sights, Figure 3, as it is very difficultto focus an object on the cross-hairs oithe telescope, even when flying at sixtymiles an hour, until after the object is lo-cated.

(CoH/miit'(i on page 754)


RadiumiPaint in the WarTHE persistent electrical activity ofradium, especially when used in com-

bination with zinc sulfid, which givesrise to a luminous effect which isreadily noticeable in the dark, has

led to the adoption of this peculiar mixturefor many different uses in the great worldwar. A large English concern has beenextremely busy of late turning out these"luminous paint" articles for use by thesoldiers and sailors of His Majesty theKing.

enemies in the dark by the second line ofmen who follow.The illustration. Fig. 2. shows a most

useful beacon provided witli a spike to bedriven in the ground. They are also madein the shape of large buttons, the luminouspainted top being covered with transparentcelluloid, and surmounted on a small steelspike ^-inch long, which, by pushing, en-ters into any woodwork, and when affixt tothe top of short stakes driven into theground and placed 10 yards apart, afford a

Radium Paint Is Finding Many Diversified Applications in the World War. In the Formof "Beacons" It Guides the Stretcher-Bearers Thru "No-Man's" Land and Enables Sig-

naling to Be Carried on Safely in the Front- Line Trenches.

Over 100,000 marching compasses are indaily use by the allied armies, each fittedvitli a luminous radium dial readable atany time, e\ en on the darkest night. Aero-planes skim along thru the night, the avia-tors guided by radium be-dialed compasses.At sea, the doughty little "sub" destroyersshoot hither and thither with never a lightto be seenthe radium lighted compass dialanswers the question. The man using itcan see the dial all the time, but you cannot.Fig. 1 illustrates a clever use for "luminouspaint" collars. These linen tabs present aluminous surface of 10 square inches, andate for attachment to the back of the tunic,so that when the first line of men go overthe top, they will not be mistaken for

guide to relief parties going and returningin the dark. One hundred of these 10 yardsapart will serve 1.000 yards, the stakes be-ing placed in the day on chosen fairly levelground.One of the most useful articles for dark

night operations is "luminous tape." Thistape, if placed on the ground and securedby stakes, metal rods or stones, is preventedfrom being shifted by the wind. The "tapelayer" places the tape in position during theday, choosing a safe path across the coun-try, and diverting from the straight pathaccording to the condition of the ground.The path should be wide enough for men tomarch four abreast up one side of the tapeand returning the otlier side, say, in all

about 12 feet wide. Where this is not pos-sible the tape layer makes a break in thetape every few yards, and starts again con-tinuously when the path is wider. Anyobstacle in the way, such as a tree or post,could have a small length of tape tiedaround it (see Fig. 3).

Should a ditch come across the path hewould lay short pieces of the tape at rightangles on either side of the ditch. In caseof the ditch being over 4 feet deep, theman should have a luminous beacon withhim and write on it the depth of the ditch,also the width, with a special pencil, andplace it by the tape, when near the ditch.

It is readily possible to form large let-ters out of this tape by nailing it up withzinc nails. Such signs as "Fireman," "Doc-tor," etc., also direction arrows prove ex-tremely serviceable, see Fig. 3.The luminious tape is also very useful

for the work of the medical corpsthetape-layer by daylight choosing fairly levelground to guide the stretcher bearersthussaving their labor in the dark, with lessjolting to the wounded. Moreover, lampsafford a mark for the enemywhereas thetape can only be seen by those immediatelyover itenabling work to be done silentlyin the dark, the darker the better.

Signaling in the front line trenches atnight is always a precarious undertaking.Luminous paint beacons have been usedvery successfully for signaling silently bynight. They are specially useful in trencheswhich are in close proximity to the enemy,,saving the need of whispering the wordsof command, which causes a hushing sound,when complete silence is required for lis-tening to the enemies' movements. Theseluminous beacons will carry a message adistance of 20 yards or 60 feet; sufficientfor all average requirements. The signal-ing can be either done with the Morse codeor by describing large capital letters ofthe alphabet the reverse way, and by thehand waving them in the air. The RoyalEngineers of the English army are said tohave been the first to use these novel, yetwonderful signaling devices.

TO TELEGRAPH PHOTOS BE-TWEEN BERLIN AND CON-STANTINOPLE BY KORN

SYSTEM.It is reported that Dr. Korn, the eminent

German scientist, proposes to introduce hissystem for the telegraphic transmission ofpictures on the Berlin-Vienna-Sophia-Con-stantinople-Bagdad route.For this purpose either telegraphic or

telephonic connections can be utilized. Sofar as telephone connections are concerned,one could conceive stations at Vienna andBudapest in connection with Berlin, thelines being occupied for a quarter of anhour only. In these circumstances picturesof an event taking place in the afternooncould appear the next day in the Viennajournals. Transmission for longer dis-tances, such as from Berlin to Constanti-nople, would involve the use of telegraphiclines, which would enable an ordinary pho-tograph to be transmitted in about an hour.The chief expense involved is the occupa-tion of telegraph and telephone lines be-tween such distances, but it is thought thatthe governments of the four countries con-cerned might grant ver\- moderate rates ifthe lines were only used during hours whenthere is little or no traffic.

December, 1917 THE ELECTRICAL EXPERIMENTER

ELECTRIC XMAS TOYS513


Daylight Signaling With Electric SearchlightWHILE the electric searchlight is

used very often for signalingpurposes at night, by means of asuitable shutter device, enablingthe operator to send out short and

long flashes of light corresponding to thesignals of the telegraphic code, it seemssomewhat paradoxical to think of signalingin broad daylight with a small electricsearchlight.

Such is the case, however, as the accom-panying photograph tends to corroborate,this particular illustration show-ing a member of the FrenchSignal Corps in the act of signal-ing to an aeroplane in flight.While very efficient wireless

communication apparatus havebeen developed for aircraft re-quirements, the range is some-what limited under certain con-ditions, and this improvedscheme of signaling in daytimeas well as night, for carrymg oncommunication between two ormore aeroplanes or between anaeroplane and the ground, comesas a very welcome auxiliary tothe aforesaid means of signalinggun ranges, etc.As our front cover illustration

shows, as well as the accompany-ing official photograph, theminiature searchlight used forcarrying on communication bymeans of short and long flashesof light corresponding to thedots and dashes of the tele-graphic code, is a very simpleaffair, and not as cumbersome asmight be imagined off hand.When the searchlight is to beused, it is held in the hands ofthe operator in such a marmerthat it will bring the telescopeinto sighting position, the tele-scope member being attached tothe top of the searchlight frame.The operator then aims thesearchlight at the aeroplane withwhich communication is to beestablisht and maintained. Hethen transmits tlie message bymeans of a telegraph key mountedon the side of the searchlight.

In this way, long and shortflashes of light are sent out,spelling out the desired words X)Tnumerals in the telegraphic code.The telescope enables the oper-ator to see the distant flashes ofthe answering light beam fromthe aeroplane, and thus it be-comes possible to carry on com-munication both ways.The searchlight is operated

from a portable storage battery, which iscontained in the carrying case, shown in theillustration, the case being provided withsuitable rheostat and control switches, sothat the light may be burnt constantly atthe highest efficiency.The entire outfit, altho it has a range

of 10,000 feet or approximately two milesin broad daylight, and about twice thisrange at night, is very light in weight. Itmight be imagined that such a beam of lightused for important and secret communica-tion with a signal corps post on land, might

be intercepted by the enemy, but such isnot the case, and besides if such a state ofaffairs should happen to occur, it is quitepossible that the enemy would not gainmuch valuable information. This is so forthe reason that these messages are sentin a special cipher, and moreover the make-up of the code is changed frequently.

In order that the aviator may knowwhere to look for these visual signals, theland operator is stationed near a sort oftent, made of four brightly colored cloth

GRAVITY REVERSED.Absolute proof that the gravitational at-

traction between masses of matter varieswith changes in their electrical potentialdue to electrical charges upon them hasbeen obtained by Dr. Francis E. Nipher ina whole year of experiments in the privatelaboratory of Washington University, St.Louis, financially backed by the CarnegieInstitution.Dr. Nipher is one of the greatest

authorities in tlie world on electrical meas-urements and the nature of electric cur-rents.

He suspended two spheres oflead, one inch in diameter, fromsilk fibres about 5 feet 8 inchesIpng inside an insulating screenspecially constructed of wood,metal, cardboard, wax and glass,with a layer of air in the middle,and cut off radiation from thesky and all changes in tem-perature. Spheres of lead teninches in diameter were adjust-ably mounted below and a tele-scope was set to peer thru aslit in the screen, opposite to aspecially designed scale.An influence machine, driven

by a single phase motor, wasused for varying the electricalpotential in the lead spheres.

Dr. Nipher not only dimin-ished the gravitational attrac-tion by charges of electricityupon the large spheres, but hereduced it to zero and thenturned it into repulsion. He wasable to measure this repulsion,and at times it reached a de-crease of 250 per cent in thenormal value of the gravita-tional attraction.

Photo (c5 By International Film Service

The French Army Has Recently Perfected a Miniature Searchlightand Telescope for Signaling To and From Aircraft in Daylight, asWell as at Night. It Has a Range of Two Miles in Broad Daylight.

strips, as portrayed graphically on our frontcover. From above, these strips appear asa bright cross, visible from a great height.Below, on the ground is placed anotherpiece of cloth showing the aeroplane in-signia, in this case the newly adopted redcentral spot on a white field, surroundedby a blue starthe American colors.

The winds at Curacao are so steady thatthree wireless stations depend upon windmills for power.

HIST! GERMAN RADIOSPIES.

The wireless operator at divi-sion headquarters at one of theNational Army camps got ashock recently that will not beduplicated until the troops start"over the top."He was playing idly with the

condensers of his apparatus try-ing to pick up a word or twofrom Arlington or Honolulu andnot getting much when the re-ceivers began to crack

;

"C-Q" came the general call."C-Q""C-Q."And the character of the spark

showed that the sending instru-ment was close at hand. All thesleuths of the signal corps pre-pared to chase this interloper tohis lair.He began to have visions of

illegal plants hidden in the bayous of thegulf coastof spies carrying on their workunder the very fence of the camp."Who are you?" he flashed at once. "By

what right are you operating a radio?"It's hard luck to spoil a thrilling story

like this, but right here the whole plot blewup.

"I'm Jones, came the answer at a rateof about 20 words a minute. "I'm Jones,sending from the 124th field artilleryuseof set approved by Lieutenant-Colonel H.B. Hackett. Nice evening, isn't it?"

DATE OF ISSUE.

As many of our readers have recently become unduly agitated as to when they could obtain The ElectricalExpERiMF.N'TER, wc -jiish to stale that the iicTi'sstands Aar'c the journal on sale between the ttvelfth and the eighteenth of the month inthe eastern fart of the United States and about the t^irnticlh of the month west of the Mississippi River. Our subscribers should be inpossession of their copies at these dates. Kindly bear in mind, however, that publications are not handled with the same dispatch by thePost Office as a letter. For this reason delays are frequent, therefore kindly be patient and do not send us complaints as to non-arrivalof your copy before the twenty-fifth of the month.


The Marvels of Radio-Activity

Heat Emission of Radio-Active Matter.

IN1903, it was shown by Curie and

Laborde that a radium compound wasalways hotter than the surrounding airand radiated heat at a constant rate of118 gram calories per hour per gram

of radium. This means that a gram ofradium, or 0.0028, pound, will boil about0.0045 pound of water every hour. Enoughradium properly contained, would run aboiler continuously with only the additionof water. There is now no doubt that theevolution of heat by radium, and otherradio-active substances, is a secondaryphenomenon resulting mainly from the ex-pulsion of alpha particles. Since the latterhave a large kinetic energy due to theirhigh velocity, and are easily stopt by matter,they are absorbed by the radium itself orits immediate container, and the energy ofmotion is converted into heat. From this,the evolution of heat is proportional to thetime agA number of alpha particles ex-pelled, as the kinetic energy transformed isin lurn dependent on the expelled particles.Rutherford and Barnes first confirmed thisview by their experiments. They showedthat emanation and the following productswere responsible for about three-fourthsof the heat evolved by radium in equili-brium.The heating effect decays with the activity,

as observed in studies of emanation. Theproducts radium A, and radium C, eachhave a heating effect proportional to theiractivity. Measurements of the heating ef-fect of thorium, uranium, pitchblende, andpolonium have been made, the evolution ofheat being in each case proportional to thekinetic energy of the alpha particles.An enormous amount of energy accom-

panies the transformation of radio-activematter where alpha particles are emitted.It must be remembered that these particlesare themselves matter, as was said before,and hence have energy when traveling ata high rate of speed, just as does a thrownbaseball, for example, the emanation fromone gram of radium in equilibrium, withits products, emits heat initially at the rateof 90 gram calories per hour. The totalheat emitted during its transformation isabout 12,000 gram calories, enough heat tochange 0.12 pound of ice into steam. Sincethe initial volume of the emanation fromone gram of radium is 0.06 cubic centi-meters, one cubic centimeter of emanationwill emit during its lifetime 20,000,000 gramcalories of heat. Now taking the atomicweight of the emanation as 222, one gram,or 0.0022 pound, of radium emanation will

ya/ye Helium VclyeFig. 2

(

Fig. 2.Apparatus Used In ProducingHelium from Radium Emanation. TheAlpha Rays Pass Thru the Thin Glass

Inner Wall and Produce Helium.

give off 2,000,000,000 gram calories of heat.Let us assume a boiler that evaporates

100 pounds of water per hour at normalboiling point and atmospheric pressure, thetemperature of the water to be 15 C, or60 F. Then, neglecting the absorption ofheat by the boiler itself, the heat necessary

By JEROME S. MARCUS, B.Sc. (Ch. E.)PART IV. (Conclusion.)

per hour will be lOOx (10015) xlOOO/2.2.3r 3,863,000 gram calories ( 1000 grams equals2.2 pounds, and 1(X)15 or 85 is the rise intemperature). Then dividing 2,000,000,000by 3,863,000 we have 516.7. So one gramof radium emanation will, by decaying, giveolf enough heat to run such a boiler 516.7hours continuously, evaporating 51,670pounds of water. (See Fig. 1.)

This evolution of heat is really enormouscompared with that emitted by any knownchemical reaction. And there is everyreason to believe that the total evolution ofenergy from any type of radio-active matterduring transformation is of similar propor-tions to that of the radium emanation. Theatoms of matter must consequently beregarded as containing enormous stores ofenergy, which are released by the disinteg-ration of the atom. Investigations alongthe lines of the electronic theory of atomicstructure bear out this view.*

Prodl'ction of Helium

In 1902 Rutherford and Soddy suggestedthat the helium which is invariably foundaccompanying radio-active minerals wasderived from the breaking up of the radio-active matter. A year later Ramsay andSoddy, in their famous researches whichrecalled to us thru newspaper comment theold alchemy, definitely showed that helium,a gas we consider as an individual element,was produced by radium and also by itsemanation. The presence of helium in theatmosphere of the sun is one of the argu-ments for radio-active matter in the bodyof the sun itself. It seemed very probable,that from its observed mass, the alpha par-ticle was an atom of helium. This wasproven by tlie work of Rutherford andGeiger who showed the alpha particle to bean atom of helium, carrying two unitcharges of electricity. Hence, a form oftransmutation of matter according to ourgeneral theories of chemistry has reallytaken place.

In order to prove this definitely, it wasnecessary to show that the alpha particlesthemselves give rise to helium. Rutherfordand Rayes did this by allowing the alpharays from a large amount of emanation topass thru the very thin glass walls of thecontaining tube. The collected particlesgave the spectrum of helium, proving themto be indubitably helium atoms. (Fig. 2.)

Hence, all radio-active matter expellingalpha particles gives rise to helium. Therate of production of helium as calculatedby Rutherford and Geiger, who counted theparticles and measured their charge, shouldbe 158 cubic millimeters per year. Thinkof working with a quantity so small! Aclose agreement is shown by the observa-tions of Boltwood and Rutherford, whofound the production to be 163 cubic milli-meters per year.

Products of Radium

The successive transformations of radiumwere shown in the table in the last article(part III) of this series. When a wirecharged negatively has been exposed forsome time to radium emanation it becomescoated with a thin film of radium A, B, andC. .'Kbout twenty minutes after the removalof the wire from the emanation, radium A

has practically disappeared and the raysarise entirely from radium C. This hasproven of great value in measurements, asradium C is a source of an intense homo-geneous alpha radiation. The wire, how-ever, still shows a residual activity, very

/ &rom of emanation milerofiorate 5I.6T0 pounds of /'^water ' {i

C ' i' 'i '''''' '^ 1

'

1

'

1

Radium \ \boiler ! 1_ ^r~T'

^

^-.\'/\/\.}/--^F/gJ 31

A few years ago, H. G. Wells, in a story ap-pearing in The Century Ma-jasine, used this en-ergy as a weapon in the world war which hepredicted. The story is really fascinating.

Fig. 1.A Theoretical Radium Boiler.One Gram of Radium Emanation WillEvaporate 51,670 Pounds of Water, Before

It Becomes Exhausted.

small and reaching a maximum in aboutthree years. The slow change, of course,consists in the successive transformationsin the series.Radium D is rayless, and of a calculated

period of 17 years. It was at first thoughtthat radium E was complex, but no specialevidence has been observed. Radium F isidentical with polonium, the first activematerial separated by Mme. Curie. Sim-ilarly, radium D is the source of activityin "Radio-lead."

It is interesting to note the valuableresults acquired from the observation of theextremely minute residual deposits fromemanation.

R.IUM Em.\nation

The radium emanation has been purifiedby condensing it in liquid air, and thenpumping oflF the residual gases. In a purestate the emanation is, weight for weight,100,000 times as active as pure radium.Pure emanation in a spectrum tube givescharacteristic bright lines. The electricaldischarge in the gas (Geissler tube action)is of a bluish color, continued sparkingdriving the emanation into the tube wallsand electrodes. Even with the minutequantities obtainable, the boiling point hasbeen determined as 71 C. When first con-densed, liquid emanation is colorless, atlower temperatures it freezes, while at thetemperature of liquid air it has a brightrose-colored glow. The density of liquidemanation is about 5.5.The emanation has definite chemical

properties, and belongs to the group ofmonatomic inert gases, with argon, helium,etc. It is somewhat soluble in water, andreadily absorbed by charcoal.h large amount of work has been done

in measuring the amount of thorium andradium emanation in the atmosphere, andin determining the quantity of radium andthorium in the earth's surface. Importanttheories regarding atmospheric electricity(the aurora borcalis, etc.) and bearing ongeology are based on this work.

Origin of Radium

Radium is separated from the twouranium minerals, pitchblende and carnotite,the former coming from Austria, and the

{Continued on page 572)


How I Telegraph PicturesTHE ELECTRICAL EXPERI-MENTER has asked me to explain

to its readers my system for thetransmission of pictures by electricity i.e., Telegraphing pictures. The

actual workings of the instruments havenever before been explained in detail to thereaders of any periodical.The idea of telegraphing pictures is not

way. I perceived immediately that a picturecomposed all of black and white could bemade to make and break a current by form-ing the black or white on an insulatingmaterial upon a metal plate and causing acurrent to pass from the plate to a tracingneedle, so that the insulating parts wouldbreak the said current.

Photograph of President Wilson As Re-produced At Distant End of TelegraphCircuit By Mr. Leishman's Recently

Perfected Apparatus.

new ; in fact, a scheme for accomplishingthis was suggested fully seventy years ago.Of recent years, most experimenters thathave entered this field have made use of thepeculiar property of selenium for changingits electrical resistance when exposed tolight. My system is far less complicatedand expensive than those using selenium,and it is possible by its use to receive avery clear and distinct picture at almosttwice the speed heretofore obtainable. Itis needless to say that I make use of prin-ciples entirely different fromthose upon which other ma-chines are based. This is dueto the fact that I entered thisfield entirely ignorant of anyother single wire system, myentire attention having pre-viously been given to certainmathematical instruments.

In order to make this dis-cussion wthin the under-standing of all, I shall avoidall technical language andmake the explanation as sim-ple as possible. Let it first beunderstood that the telegraph-ing of pictures is not tele-vision; it does not make itpossible to see the person towhom you are telephoning, asthat would necessitate thetransmission of moving pic-tures, or about seventeen pic-tures per second. At thepresent time, such a thing isimpossible for both electricaland mechanical reasons. Itis possible, however, to sendand receive one picture in a very few min-utes. Some people ask what would happenshould the picture collide with a building.This, as readers of The Electrical Experi-menter probably know, cannot happen be-

cause the actual picture being transmittedremains at tlie sending machine, a reproduc-tion being effected at the receiving end bythe building up of minute portions, one at atime, until the entire picture is received.The telegraphing of pictures therefore

resolves itself into the following distinctelements : A means for gradually coveringthe entire surface of the picture by somedevice capable of translating the light andthe shade of the picture into pulsations orvariations of an electrical current ; and ameans for successively recording these pul-sations or variations in the form of whatappears to be graduations of light andshade.How I accomplish these things can best

be shown by first explaining how the tinyparts of the picture are successively trans-mitted and recorded. Obviously, this canbest be done by an arrangement similar toa cylinder phonograph or dictating machine,both the sending and receiving instrumentsusing this mechanism. The carriage thatis sending or receiving, gradually progressesfrom one end of the cylinder to the otheron a spiral or screw, and the picture itselfrotates on the cylinder. This makes it pos-sible for all parts of the picture to becovered in the same succession at both endsof the line. The cylinders must of courserevolve in exact synchronistn to preventdistortion, but for the sake of clearnessthis will be explained later.The next problem is that of causing

light and shade to affect the passage ofan electrical current. This, of course, prop-erly constitutes the sending device. Aspreviously stated, some systems vary anelectrical current by causing the light andshade of the picture to act upon a portionof selenium thru which the current passes.This is a very direct way of solving the

'^i

ii^^:

Mr. Leishman and His Machine For Telegraphing Pictures,Script, Etc., Over Telegraph Or Telephone Lines.

problem, because there must be an "eye"that recognizes light and shade and thatwill vary an electrical current accordingly.It is possible, however, to accomplish thisin an easier, cheaper and less complicated

Another Sample of the Work Which theLeishman Machine Will Reproduce Ina Few Minutes Over Existing Telegraph

Circuits.

This idea then had to be elaborated uponto permit the transmission of a half-tone.All newspaper half-tones, and the greatmajority of those in magazines, are reallycomposed entirely of black or white ; thatis, any given point is either the one orthe other. Examine one of these picturesclosely and you will find it to be composedentirely of little black dots, the shadedeffect being an optical illusion due to thesize of the dots. There are a fixt numberof these dots to the linear inch, varying in

newspaper work from fortyto eight>'. If the half-tone iswhat is known as sixty screen,then there are sixty dots tothe linear inch ; and the lightand shade, as before stated,is produced by the size of thedots, the lighter portions hav-ing small dots and the largerportions large dots that some-times join and produce a massof black.These dots may of course

be formed of insulation andwill break the current for aperiod of time proportionateto their size. This is the gen-eral idea of transmitting ahalf-tone.Before explaining the ex-

act operation of my picturetransmitting device, it maybe well to explain the methodof preparing the half-tone inorder to obtain the insulatingdots. For this, I follow up toa certain point the regularprocess of photo-engraving.

The picture to be transmitted is firstphotographed thru a screen, the functionof which is to break up the picture intodots whose sizes vary as previously ex-plained. A copper or zinc plate is then

Photos,


coated with a solution of glue, bichromatof ammonia and water. This is placed incontact with the developed negative and isexposed to strong light. The bichromat ofammonia is the element acted upon. Whenthe plate is washed, the part that has notreceived the light washes away, leaving therest fixt to the plate. Upon heating, thegelatine picture turns to a chocolate color.

The regular photo-engraving process goesstill further, but this is all that is necessaryin the preparation of a picture for trans-mission, as the dark portions form a verythin and highly satisfactory insulation.The plate is then rolled into a thin cylin-

der and slipt over the cylinder of themachine. The transmitting carriage con-sists of an arm into the end of which maybe screwed an ordinary phonograph needle,which is held against the plate by a spring.A current passes between the needle andthe cylinder excepting when an insulatingdot passes beneath the needle. As pre-viously explained, the mechanism permitsthe needle to cover every part of thepicture. In this manner a picture is trans-mitted.At the receiving end of the line, the

current from the transmitting machinepasses thru the coils of the electro-magnetson the receiving carriage. These attracta very light armature, causing the saffire ordiamond in the forward end to press againstthe cylinder. This pressure does the re-cording. The stylus may be made to cut astencil ; scratch camphor smoke from whiteenameled paper ; scrape white wax from darkpaper ; or press upon a carbon sheet, therebyrecording and reproducing the picture uponordinary paper. The pictures illustratingthis article were received by the lattermethod. In this manner, all the dots on thesending machine are accurately reproducedon the paper at the receiving end. Thesedots, since they vary in size according tothe light and shade of the picture, form anexcellent half-tone likeness of the originalobject.Some of the readers of this article may

wonder why the recording is not done bymaking a pen out of the receiving stylusand causing it to write upon ordinary paper.The reason lies in the fact that a pen andink arrangement is necessarily more com-plex than the system above explained ; itgets out of order easier, and when recordingat the rate of


PHOTOGRAPHING LIGHTNING.To many timid persons the fine artfor

art it really isof snap-shotting "lightning"is actually about the most dangerous job to

An Excellent Photograph of Ribbon Light-ning Taken In Iowa the Past Summer. This

Is What We Mean by "Odd Photos."

be found. But many amateurs and profes-sionals have taken excellent photographs oflightning discharges and still live to tellthe tale. For instance witness the accom-panying photo taken last summer by theRev. C. Lilie, of Iowa.To take a pood "lightning" photo is more

often than not a matter of pure chance.Having loaded up the camera, the first thingto do is to open the shutter for a time ex-posure ; as soon as the first flash appearsclose the shutter quickly. The job is done.Simply develop the plate in the usual man-ner. Heat or flash lightning will give pecu-liar results. The writer took several photosof heat lightning recently and the resultsare^an ordinary photograph of the sur-rounding landscape, just as if the sun hadbeen shining. Combinations of forked andheat lightning often yield excellent pictures.Chain or forked lightning will produce astartling photo if the camera is swung fromside to side while taking the picture.

ELECTRICITY AND GOLD FISHES.By H. Gernsback

Not .so long ago, the writer, while watch-ing some gold fishes at play in hisaquarium had the idea of testing the fishesas to the effect electricity would have uponthese highly sensitive animals. Accordinglytwo metal plates were sunk into the tank-as shown in the illustration, and threebatteries were connected to the two plates.A curious thing at once happened. Using

a current of three dry cells and upon clos-ing the switch, all the fish immediatelygrouped themselves parallel with the platesand as long as the current was left on thefish remained in this position, refusing toswim or move in any other way but parallelto the plates.The explanation of this phenomenon of

course is that the current traveling fromplate to plate, traverses the fishes' bodies,and as a fish is longer than it is wide, andas it is quite sensitive to the electrical cur-

rent, it follows that inasmuch as the currentprobably proved disagreeable to the ani-mal, it presented the shortest path to thecurrent by placing itself parallel to theplates. It seems the fish did not cherishthe idea of taking the full strength of thecurrent thru the nose and mouth and thencethru the sensitive fins of the tail.Another thing observed was, that the

moment the switch was closed, there was acertain amount of excitement among thefish and if the closing and the opening ofthe switch was kept up, they would dartaround in a most extraordinary manner,while thus under the influence of the cur-rent. As soon as the current was turnedon and left on, however, the fish did notseem to be uncomfortable except that theyonly moved parallel with the plates as abovementioned. Another point observed wasthat while under the influence of the elec-trical current, the fish refused to come upand feed tho quite hungry, having gonewithout food for twenty-four hours. Theinstant the current was disconnected, thefish immediately would begin feeding, butdid not seem to be quite so anxious as atother times. This would tend to show thatthe electrical current was not of immediatebenefit to them, altho this can not be vouch-safed, the e.xperiment having not extendedover a sufficiently long period. At any rate,the fish did not seem to be harmed by thecontinuous application of the current, andafter a few hours, seemed to be as livelyas ever.

When Battery Current Was Connected to TwoMetal Plates in a Gold Fish Aquarium, theFish Immediately Grouped Themselves Par-allel With the Plates, as Shown in Lower Cut.

Alternating current from a step-down toytransformer was also tried, but strange tosay the fish were hardly affected by thisform of current. This was rather unex-pected, inasmuch as a rather convulsiveaction of the fish was thought to take place.

ELECTRICITY WASHES CLOTHESFOR U. S. TARS.

"Somewhere on the Atlantic," electricityis "taking in washing"doing good workfor Uncle Sam's Tars. On the supply, or"mother," ship an American electric laun-dry is operated, said to be the most com-plete and modern ever seen in that part ofthe world. The "boys" report that thework is perfect, and prices less than halfthose at home. One of the features of theship's laundry is a complete soap factory.

NURSERY RHYMES TO DATE.By John T. Dwver.

Sing a song of sixpence,Of "muckers" brave and bold.Who turn the household upside downIn search of things untold

Pins and needles; clocks and jars,All articles of useAre soon upon the missing list.When a "mucker" is turned loose.*******Little Jack Horner,Sat in a cornerEating a CURRENT pie.He put in his thumb.And then cried, "bv gum

!

This is SHOCKING indeed. Oh ! my."*******There is a fellow in our townAnd he is wondrous wise,The things he doesn't know aboutWould fill a "skeeter's" eyes.

Now, it's got some folks a'guessingHow he could get such knowledge.The more so, when they do considerThat he never went to college.

But to me the matter's simple-

And the reason can be seen;He's merely one of many moreWHO READ THIS MAGAZINE.

NOVEL SHADE FOR INCANDES-CENT LAMPS.

A simple design for an efficient incandes-cent lamp shade is described in a U. S.patent recently issued to Frederick R. Popeof London, England. This invention de-scribes a type of shade which closely sur-rounds the upper portion of the lamp bulb,and which also serves as a reflector to di-rect and concentrate the light rays. It isclaimed to be particularly efficient in loca-tions where the supporting structure for thelamp is subject to a heavy vibration, as infactories and like places.The arrangement, in brief, comprises an

annular threaded collar, which screws onto a threaded sleeve on the lamp baseproper. The collar is preferably U-shapedin cross-section, and forms a seat for aflange formed on the narrow end or neckof the shade. The shade may be of por-celain or any other material suitable forthe purpose. It is very easy to replace theshade at any time, as the shade as well asthe retaining collar both slip over the lampbase, as they are both of larger diameterthan the screw plug forming the base ofthe lamp.

An Electric Shade for Incandescent LampsThat Screws Onto a Threaded Collar, so as

to Be Supported by the Lamp Itself.


ELECTRICALLY HEATING THEFISH TANK.

Tlie advantages to be obtained from theheat of electric energy are many and great,both as regards thermal efficiency as well

as ease of application. Greater thermal

efficiency is obtained in that electric energy-

is transformed into heat at 100% efficiencyand is utilized at from 3J/2 to 4 times theefficiency of fuel combustion devices.Here we have the Fish Tank electric

heater. The customer has an aquarium inhis residence containing fish brought froma warm climate. This necessitates warm-ing the water which is accomplisht by in-stalling a heater of the immersion type inthe feed pipe supplying water to the tank.This heater unit is indicated by the arrowin the photograph.Among other things, electrically made

heat is clean, safe and sanitary. It can beused in any atmosphere and generated inany quantity or at any temperature desired.By its use the fire hazard is greatly reducedand the working conditions of labor vastlyimproved. It is susceptible of perfect andautomatic control as regards localization,time and temperature to an extent not yetattained with any other method, and exactconditions can be duplicated at will.The heating unit is invariably small, com-

pact and substantially built, which allows ofgreater flexibility in application than withany other heating device. When applied tovarious industries or processes of those in-dustries each unit has its own specific ad-vantage.

In heating of liquids, melting of metal inpots and hotplate work, the units are soshaped and embedded in tlie apparatus usedand of such thermal characteristics as toaccomplish the work with the least possibleexpenditure of time and energy and at high-est efficiency.

"GIVE SOMETHING ELECTRICALTHIS CHRISTMAS."

Higher wages, consequently more moneyto spend; a newly created desire for con-

WOMEN MAKE GOOD RADIOOPERATORS.

The accompanying illustration shows anumber of women being taught the rudi-

Women Radio Students Are Daily Increasing in All Parts of the Country. This GroupWas Snapt Hard at Work in a New York City College.

veniences and the demand for thrift areall working to make this year the bannerChristmas year for the electrical industry.The strong appeal of practical electrical

gifts for the home will bring scores of peo-ple into the electrical shops where formerlythey have been buying toys and knickknacks.

ments of Radio-telegraphy at one of theleading colleges in New York City.The photograph is reproduced thru the

courtesy of the National League for ]Vom-en's Sen'ice. These women who takeup the study of wireless will find plentj-to do in helping their country to win thewar.

and realizing the trend of opinion. The So-ciety for Electrical Deielopment has planneda big nation-wide Christmas Gift Cam-paign. The broadside announcing thisCampaign has been mailed to 20.000 per-sons. The features of ".\merica'5 Electri-cal Christmas" are outlined and inforrna-tion given regarding the display publicit3'material available to help the electrical in-dustry get its share of the $200,000,000 an-nually spent for holiday presents.Remembering the success of "Electrical

Prosperity Week, 1915", ".America's Elec-tical Week, 1916", "Wire Your HomeTime", central stations, manufacturers, job-bers and contractor-dealers will realizeupon this opportunit>'. The electrical in-dustry never has gotten its share of thebig money spent in Christmas gifts. Thisis the first concerted effort in this direction,and the time is opportune for an immensebusiness.The sales helps being prepared for the

campaign with the slogan "Give SomethingElectrical This Christmas" include a spe-cial holiday edition of the Monthly SalesService of the Society. Timely advertisingsuggestions will be given and special win-dow displays will be shown.

Photo Courlesy Society for Electrii-al Peveloi'nientThis Picture Shows How an Electrical Heater (See Arrow) Was Adapted to Warm

the Water In a Fish Tank Containing Tropical Members of the Finny Tribe.

CORRECTION NOTICE.We wish to correct a statement made in

the article entitled "Historic Electric Ap-paratus," which appeared in the Xovemberissue, concerning the history of "Wireless."The first trans-Atlantic radio signal (theletter "S") was recived at St. Johns, New-foundland, instead of Cape Cod, Mass.


FAN FLAME SPARK PLUG THELATEST.

Any plug will spark when it's new andclean. But no ordinary spark plug actuallyadds power to the motor, actually cleansitself, and still is so simple and sturdy in

construction that it isunaffected by the mostsevere conditions ofheat, speed and highcompression, say thesponsors of the FanFlame plug.The center elec-

trode of the fanflame plug terminatesin a miniature rotaryfan which is heatproof because it is98% pure nickel. Thisfan is constantly ro-tated at high speed bythe successive com-pressions and explo-sions.The whirling fan

produces a circle offlame instead of amere spark. It liter-ally throws a showerof fire in every direc-tion, igniting the com-prest gas severaltimes as rapidly as anordinary spark can doit.

By careful tests themakers claim to haveproved that thenickel fan constantly

This Spark PlugHas a Fan Elec-trode That Re-

volves.

rotates in the cylinder when the engine isin operation.The effect of the rapidly whirling blades

is to throw off all oil and soot by centrifu-gal force so that the sparking points arealways clean, and the accumulation of sooton the rest of the plug is also retarded.

A 40,000 AMPERE SWITCH.The accompanying illustration shows a

remarkable end-cell storage battery switchwhich has a steady capacity of 10,000 am-peres or a momentary load of 40,000amperes for six minutes. It is used forregulating the voltage of storage batteriesin large central stations.The construction of the 10,000 ampere

cell switches is shown clearly. Eachswitch has two horizontal rails of rec-tangular section and two rows of massivecontact points, arranged alternately at thecorners of an imaginary square, the four

traveling brushes occupying the sides ofthe square. The brushes are mounted onand suitably insulated from a travelingcarriage, driven by the horizontal drivingscrew. Two 10,000 ampere cell switchesare shown in the illustration herewith.The driving screw in each case runs the

entire length of the switch, and is gearedto a motor at one end. This motor is pro-vided with semi-automatic distant control,so that tlie switchboard operatorcan start the brush in either direc-tion from any point and bringit into full contact with any otherpoint, but cannot stop it betweentwo adjacent points.Two electro-magnets, of the

plunger type, located adjacent tothe motor and excited selectivelyby the control circuit from theswitchboard, serve to operate con-tact switches to connect the motorarmature for either direction oftravel, respectively. As soon aseither plunger starts upward itbreaks the exciting circuit of theother magnet, thus preventing anypossible conflict between the two.As soon as the motor starts, a

cam wheel so geared to the motoras to make one complete revolu-tion while the brush is travelingbetween two adjacent points, locksthe active magnet plunger in position, thusmaintaining the motor in constant actionbetween switch points.

from the incandescent lamp are cast intothe eyes of the physician, and more free-dom of the hands is obtained by its use asbecomes readily apparent, owing to the factthat three separate and distinct instrumentsare combined in one. A push-button switchis provided to open and close the lamp-circuit as desired. This idea has been pat-ented by Hermann Weder, Sr., and CharlesH. Wolff of Philadelphia, Pa.

A Recentand

Invention Comprises a Diagnostic Lamp, LenSiTongue Depressor All in One Instrument.

HEATING PERSONS INSTEAD OFROOM IN WESTERN RESTAU-

RANT.In following up the policy of "localizing

heat," a leading electric heating concernrecently secured a contract covering theinstallation of 30 electric heaters in theTuberculosis Sanitarium of IndependentOrder of Foresters in Lopez Canyon, ashort distance from Los Angeles.These heaters will be installed, without

the stands, on the under side of the tablein the dining-room, radiating the heat down-ward to strike the floor and be radiated up,by this means keeping the bodies of thoseat the dining table warm, rather than at-tempting to heat all the air in the room.In other words, they heat the individualinstead of heating the room. Inasmuch asthe diners will only be in the room 20minutes, or half an hour during meals threetimes a day, it seemed unnecessary to at-tempt to heat the entire room, accommo-dating over 100 people, when it would onlybe occupied this short period of time.

UNIQUE COMBINATION SIGNAL-ING LAMP AND BELL.

In many instances, the orthodox form ofelectric signal or alarm is not desirable, andwith these objects in mind, Mr. ChristianReinker. an Ohio man, has devised andpatented the unique combination signallamp and bell shown in the illustrationherewith. Current is supplied to the devicefrom a battery or other source of currentthru two binding posts carried on thecentral stem at the base of the bell, andwhen the circuit is closed, the bell vibrates,while the lamp remains lighted constantly,as long as the switch remains closed. Thedesign of the signaling device is unusuallyartistic, the lamp being enclosed in anornamental chamber which is provided withone or more white or colored lenses cut inthe form of jewels.

Rear View of the Largest Storage-Battery End-Cell Switch Ever Built.It Has a Continuous Carrying Capacity of 10,000 Amperes and a

Momentary Capacity of 40,000 Amperes.

COMBINEDFLASHLIGHTAND LENS FORD I A GNOSTIC

PURPOSES.The present inven-

tion sho\\'n in theaccompanying illustra-tion is an ingeniousarrangement combin-ing a special form ofpocket flashlight withan adjustable lensholder on the side ofthe battery case, andalso means for attach-ing several forms ofdiagnostic instru-ments, such as atongue depressor,which is here shownin actual use.

Several advantagesare claimed for thisparticular form offlashlight diagnosticinstrument : for onething, no direct rays

Unique Electric Signaling Device for Use onAutos, etc. Pushing a Button Lights tha

Lamp and Rings the Bell.


OPERATING THE COFFEECUTTER BY ELECTRIC

MOTOR.By means of the cutter shown herewith

steel-cut coffee can be furnished by thegrocer in bulk with convenience and at aprofit. It is built along entirely differentlines from any of the mills on the market,and has been evolved to meet the insistentdemand for machines that would cut, notgrind, coffee.The coffee cutter cuts the coffee uni-

formly and evenly. Granulating and pul-verizing are done on the same burrs, givinga sandlike grain especially adapted to allkinds of percolators or drip pots now insuch wide use. There are two sets ofburrs, one of which revolves. The otherset is stationary. The burrs are especiallydesigned with diamond-shaped teeth. They

THIS FAN THROWS BREEZE "UP are being made now. The pins are easilyAND DOWN" AS WELL AS

SIDEWISE.The past few years have witnesst so

many novel introductions in "Fanland" that

No Up-To-Date Grocery Store Is CompleteWithout an Electric Coffee Cutter.

are self-sharpening and self-aligning, hav-ing special ball bearings which take outall play. Thus the burrs cannot "wobble"and produce uneven granulation.These machines are operated by totally

enclosed, low-speed electric motors de-sired for heavy duty and without com-heated mechanism to need adjustment,lue to the fact that a low-speed motoris employed, no gears are necessary. Themotors are equipt with radial and thrustball bearings, which reduce friction to aminimum and prevent wobbling of parts.They are silent and true running. Theonly parts needing lubrication are the ballbearings, and these need only be oiledabout once a year. Thus there is nooil to accumulate in the burr case, none toget into the coffee, and all the nuisanceof oiling is removed.

This Remarkable Electric Fan Revolves andThrows a Breeze Up and Dow^n as Well as

SIdewise.

it would seem that about every imaginableform of electric fan had been perfected orthought of, but we have to salute GustafOlson of Chicago, 111., for his very ingen-ious electric fan gear.One of the most interesting points which

had to be worked out in this idea was theshape of the gear teeth on the stationaryrack, and also those of the pinion whichmeshes with this rack, as becomes clearfrom the accompanying illustration. Thesmall driving pinion which rotates the fan-motor body proper, by means of this rack,is secured to a vertical shaft geared insidethe motor casing to the armature shaft, soas to provide a positive drive for the rota-tional function.Current is supplied to the rotating fan

motor thru a set of slip rings and brushesmounted in the base. Thus, this fan willnot only throw a breeze in every part ofthe room at a certain level, but will throwthe breeze toward the floor and also towardthe ceiling periodically or about four timesin every revolution of the fan motor, whichmay be adjusted to occupy about one fifthof a minute.

GLASS EYELETS FOR TEMPOR-ARY WIRING.

Glass push pins provided with an eyeletfor use in temporary low-voltage wiring

attached to woodwork or walls, and it ispointed out by the maker that they areparticularly useful for amateur batterywork where small wires are to be runabout the house. They should prove par-ticularly efficient in wiring up sensitiveelectrical apparatus such as galvanometers,radio receiving apparatus, etc., where aslight leak, such as thru wood, means abig difference in the efficiency of the in-strument.

NEXT! WILL YOU HAVE ANELECTRIC HAIR-CUT?

Barbering is one of the very old anduniversal trades. For years past there hasbeen practically no advance or change inthe general method employed of usingshears, razor or clipper. It is true thatthe modern clipper with its improvementsis a device which is of comparatively re-cent development, but aside from that themethods of the barber are the same asthey were hundreds of years ago, so we

A Handy Glass Eyelet for Temporary or Low-Voltage Wiring.

Good Mornlngl Have You Met the ElectricBarber? Here's the Latest Tonsorlal De-

viceA Motor-Driven Hair-Clipper.

had begun to believe that it was only stylesin trimming the hair or beard whichchange. But electricity can improve almostany unelcctrified method or device. Theelectric hair cutter here illustrated is rapid-ly becoming popular, many Chicago barbersspeaking very highly of it.As will be seen from the illustration,

the machine consists principally of a lightiron standard with cross arms at the topsupporting the small electric motor, whichis connected to the clipper by means of aflexible shaft three or four feet long. Thisshaft enters a translating device in whichthe revolving motion is changed to a hori-zontal motion for the handles of the clip-per. This is necessary in order to causethe shearing edges of the moving clipperblade to pass back and forth over the otherin the usual manner.


A TRACKLESS TROLLEY SYSTEM.By L. Schoolcraft.

In Massachusetts there are now severallines of trackless trolleys. These vehiclesresemble automobiles more than they dostreet cars, but their motive power is elec-tric and the current is obtained from over-head trollev wires.

the lungs or in the pleural cavity, justwhere a sore is situated. If the child hasswallowed a pin or a penny, it will benicely revealed.There are forsooth failures with it : not

every use of the X-rays is successful in it-self. Tuberculosis may be present andescape discovery, if the other facts found

'^rf!S^.

'^^^^

Massachusetts Now Boasts a Trackless Trolley. Th Current Is Taken from TwoWires Thru the Double Pole Arrangement Shown. The Vehicles May Pass One

Another on the Road Without Trouble.

It will be noticed in the illustration thatthere are two trolley poles on this car aswell as two over-head wires, whereas inthe ordinary street car there is but one.This is due to the fact that these cars donot run on steel tracks but on an ordinaryroad or pavement. The second trolley wirebeing for the return circuit. The cars arecontrolled by the ordinary controller as isfound in street cars.There are two advantages of this system

of trolley

FirstThe car may pass around othervehicles which may be in front of it orpassing it in an opposite direction, thus re-ducing delays.SecondThe elimination of one of the

largest items of expense in constructingelectric railways which is the track or foun-dation.

THE USE OF X-RAYS IN DISEASESOF THE CHEST.

By Dr. Leonard Keene Hirshberg,A.B., M.A., M.D.

(Johns Hopkins University.)When you look thru the greenish glass

used as a screen, when the X-rays arefocused on anyone's torso, you see an oldtime bird-cage or wire hoop-skirt with theribs as circular wires, with shadowy, fugi-five, fleeting phantoms of birds within theage. An X-ray photograph imprisons

this picture.The X-rays, with the ribs as precise guid-

ing posts, allows us to make an exact andminute examination of the topography hid-den from the unaided human senses. Aman without senses is a mental wreck.A doctor with all his senses is a most in-complete creature. He must call to theaid of his best endowments, those instru-ments of precision, which reach out to hid-den things undreamt of in his best senses,much less his philosophy. The X-rays isone of many such assistants.The X-rays can sometimes tell you to

the fraction of an inch, the exact spot in

in a physical examination are not alsotaken into consideration.

In maladies of the lungs. Dr. HowardLilienthal of the surgical staff of CornellMedical College, holds that no final judg-ment should be given unless the X-ray ob-servations are also checked up with othersoundings and investigations of the indi-vidual's state of health. He describes alittle boy's condition in support of this.The little patient in question was three

and a half years old. He began to havespells of unproductive cough. There wasno evidenceof fever orwe a k n e s sfor theyoung-ster playedabout be-t w e e n theparoxysms.When this

had gone onabout tendays, hereally be-ca m e s e-riously ill.Fever ap-peared andthe little fel-low beganto cough upmucus.

.\n exam-ination withthe stetho-scope andfingers o nthe back ofthe chest,showed it tobe a bit flatand dull insoimd withincre as edvoice p r o -

duction. It was decided that there must besome fluid or pus between the lung andchest wall. This is pleurisynot the pop-ular fallacy of a pain in the chest.An X-ray picture was then taken of the

chest on the side affected. The solid patchof dark in the negative suggested pneu-monia, but from the stethoscope examina-tion this was properly interpreted as pus-pleurisy or "empyema."An anesthetic was then given and a tiny

needle-tube was pushed into the pleuralca\ity much as a beer-keg is tapt, thematter and pus were drained away, and loand behold a second X-ray photo showeda large watermelon seed in the child's wind-pipe.

This was removed and the youngster wassoon well and happy. The two X-ray pic-tures alone would not have been enough tomake a correct diagnosis. The stethoscopealone would not have done so. A wonder-ful doctor with all the fulness of soundsenses could not have done so without theother aids.

UNIQUE BATTERY SIGNALINGLAMP WHICH STRAPS ON HAND.While the ordinary battery flashlight has

proven its efficacy in many instances, aninventor, August Sundh, has devised andpatented the flashlight signaling and il-lumination outfit here pictured. In his pat-ent he states that the apparatus is intendedand especially adapted for the use of per-sons working around machinery or in placewhere portable lights are used. Also it ispointed out that it will prove useful forautomobiles and trainmen, such as forsignaling purposes, and its use in this direc-tion is illustrated in the accompanying view,where the autoist is shown giving a nightsignal that he is about to turn a corner.The device is quite simple and merely

comprises a leather or other form resem-bling a glove, which straps on the hand andat the wrist. This glove contains a flappocket to carry a small flashlight battery-Several miniature battery lamps are dis-posed in various positions at the back of theleather mitt as the illustration discloses, andthe circuit between the battery and lampsis closed whenever desired by pressing on asmall push-button switch secured on theinside of the mitt.


CARRY THIS VACUUM CLEANERON YOUR BELT.

We think vacuum cleaners have beenperfected to the limit in this country, buthere's an English type of portable electric"suction" cleaner, as they call it over there,

Electrical Experimenter191712

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Transcript of Electrical Experimenter191712