Converter's job in Speedomax instrumis to receive the (often very small) dicurrent signal which is related to theperature, stress pH or other condibeing measured, and produce an altering voltage. This output is amplified,then directs the balancing system to nure, record, and if desired control.

Good engineering shows in this Amplijthorough filtering, high impedance,plug-in connection to the' rest ofSpeedomax.

Good engineeringshows in this Slide-wire's non-induc-tive winding andin absence of anyflexible leadswhich might forminductive loops.

0'

Good engineeshows in thisancing motsmall size, aniits torque arto operate a(sory controlsignalling fitm,

* . * * * * * *

and every Speedomax user benefits by it!

_*o The operating precision of the thousandsof Speedomax Recorders and Controllers

tents which serve industry and science begins with

'irect the engineering of components like this Con-

tem-'ition verter. Our specifications apply at all stages-

rnat- all the way back to the plants which make

and metals, insulation materials,, etc., for us. These

rzeas-specs represent also the best thinking of our

suppliers' engineers. The resulting materials are thus quality-controlled for us-and us alone.From these materials our engineers tell our factory how to makeconverter parts to truly tight specifications. Some parts require prin-cipally flatness, or elasticity, or dimensional stability. Reeds needcorrect natural frequency. Many parts of course combine variousneeds; each gets its requirements.Life tests show Fidelity and Stamina. Ingenious and often orig-

ner'd inal design creates from these parts a converter with noise levelthe equivalent to only 0.2 microvolt in an emf potentiometer circuit. And

this fidelity promotes accurate measurement and control.Running on life tests since 1948, present-model converters are todaystill well inside performance tolerances. Such a run equals 21.9years of 8-hours-a-day, 200-days-a-year-service or 1.9 years more

pthan the present age of the first Speedomax.This kind of engineered performance is also built into the amplifier,slidewire, motor and scores of other exclusively Speedomax parts.

Pring It's at your service whether you want to control a laboratory furnace,bal- plot an X-Y function, or record the facts about atoms or molecules.or's Call on L&N application engineers in selecting the range (fromdple among thousands) and measuring circuit (from among over 2300)

cces- to meet your needs. Write our nearest office, or 4926 Stenton Avenue,and Philadelphia 44, Pa.

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CAREER oppORTUNIlTIES AT L&N ha

Expasionprogam f this long-established firmhamxansio topattract0utstanding recent graduatesfetrstnes so areacin salesi an fieetr1n a d science., Qpportu nii sa ei

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Allee, Emerson, 0. Park, T. Park and Schmidt on

0 Animal EcologyThis clearly written book is without any question the definitive work in the field. Drawing fromthe related sciences of physiology, plant ecology, physics, marine biology, etc. the authors coverthe science of the relationships between living organisms and their environment with a thorough-ness never before achieved. It is a work that is indispensable to teachers and students in ecol-ogy courses.

By W. C. ALLEE, Professor of Zoology Emeritus, University of Chicago; Professor of Biology, University of Florida; ALFRED E.EMERSON, Professor of Zoology, University of Chicago; ORLANDo PARK, Professor of Zoology, Northwestern University; THOMASPARK, Professor of Zoology, University of Chicago; and KARL P. SCHMIDT, Chief Curator of Zoology, Chicago Natural HistoryMuseum. 837 pages. 6/2" x 9¼2", with 263 illustrations. $14.00.

Prosser, Brown, Bishop, Jahn and Wulff on

0 Animal PhvsiologyHere is a comparative study of the physiological and biochemical characteristics of animals. Itis an attempt fo clarify the evolutionary relationships of various kinds of animals and to describethe diverse ways in which they meet their functional and environmental requirements. The ma-terial is arranged on a functional rather than on a phylogenetic basis.From the Journal of the American Medical Association: "The best book of its kind in the Englishlanguage."

Edited by C. LADD PROSSER. By FRANK A. BROWN, JR. Professor of Biology, Northwestern University; DAVID W. BiSHOP, Professorof Physiology, University of Massachusetts; THEODORE L. JAHN, Professor of Zoology, University of California at Los Angeles;C. LADD PROSSER, Professor of Physiology, University of Illinois; and VERNER J. WULFF, Professor of Zoology, Syracuse University.888 pages, 6" x 9Y8", with 312 illustrations. $13.00.

* New (2nd) Edition . . . Gardner's NeurologyThe continuing popularity of this book is due to the clear way in which the author presents theprinciples of neurology before attempting to explain details. In the New (2nd) Edition newknowledge of basic concepts in nerve conduction, motor pathways and the cerebral cortex hasreceived special attention.

By ERNEST GARDNER, M.D., Professor of Anatomy, Wayne University College of Medicine, Detroit. 359 pages, 5X/2" x 83/4", with142 illustrations. $4.75. New!

W. B. SAUNDERS COMPANYWest Washington Sqware Philadelphia 5

September 5, 1952 1

These are typical of thesavings being made in modernlaboratories with Beckman FlameSpectrophotometers..

CUTS TIME 80%..."The Beckman DU Flame

Photometer cuts time 80% on So-dium, Potassium and 50% onCalcium determinations in bloodand urine."

-Cheney Laboratories,Glendale, California

MATTER OF MINUTESNOW . . .

"Since accurate determina-tions can be made in a matter ofminutes with the Beckman DUFlame Spectrophotometer, everylaboratory can avoid tediousgravimetric or colorimetric Sodium,Potassium and Calcium determin-ations."

-Pathology Laboratory,Hollywood-PresbyterianHospital,Los Angeles, California

IIIII

IIIIIIIIIIIIIIIIII

Efficient arrangement is made possible by compact design of Beckman DUFlame Spectrophotometer (complete unit shown).

Why Beckman Spectrophotometers arePREFERRED

Small Samples-only 1 to 3 ml. ofsample solution needed per analysis.Low Fuel Consumption-about 8 cu.ft. of Oxygen per hour and S cu.ft./hr. of acetylene or 20 cu. ft./hr.of hydrogen.Aqueous or Nonaqueous Solutions-even combustible solvents may beused.Wide Spectral Range-220 to 1,100millimicrons with high resolvingpower for quantitative determina-tions of more than 40 elements.

High Accuracy-Wavelength settingsreproducible in ultraviolet to 0.05

. . in infrared to 0.5 millimicrons.Economical-Low initial cost, low op-erating cost; highly trained technicalpersonnel are not required.Automatic Sample Positioner-Protectsoperator, is fast, convenient, pre-cise. Atomizer-burner, sample posi-tioning device, focusing mirror andadjustments all unitized into onecompact housing. All necessaryregulators and gauges are conven-iently mounted on panel.

4I* BECKMAN INSTRUMENTS, INC.SOUTH PASADENA, CALIFORNIA

Factory Service Branches: New York-Chicage-Los Angeles

leckum lintr ets mce pl Mete s Eletrides - Spectrepheteters - Wiectivity Meters - Specl lestrumeets

SCIENCE, Vol. 116

For Complete Details write tor Data File 32-38

RARE CHEMICALS OF HIGH PURITYTO SUPPLY THE NEEDS OF BIOCHEMICAL RESEARCH

Detailed, Pertinent, Ainalytical Data For Every Product

CARBOHYDRATEINTERMEDIATES

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a-Ketoglutaric Acid

Sodium w-MethylpantothenateD & L-Homocystine D-CystineD & L-Homocysteine Thiolactone DL-HydroxylysineD & L-Methionine L-ThiolhistidineD & L-Ethionine L-ErgothionineD & L-Serine Glycylglycine

L-3,4-Dihydroxyphenylalanine (DOPA)

ALSO Pyridoxal Phosphate Dimethyl-f8-PropiothetinI Phenylpyruvic Acid

CALIFORN'IA FO'U'N'DAT-IONFOR BIOCHEMICAL RESEARCH3408 Fowler Street, Los Angeles 63, Calif.A NON-PROFIT CORPORATION

SCIENCE, Vol. 116

I;. -II

BIRD

Infusion

Pump

A LONG-AWAITED ITEMTHIS new Bird Infusion Pump will meter accuratelyand continually small quantities of selected liquids, elimi-nating necessity of constant observation and refilling ofsyringes.The close regulation of flow will save you considerable in-jection fluid, and you will find a smaller number of repeatlaboratory experiments required. Operates on 115V,60 cy.

$500.00Cat. No. 71-049

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4 SC'IENCE, Vol. l11G

II~FI [I~AIJ a I1711 WJA 11.IF1Your Chance to Own a Truly Fine Precision Instrument!

IMPORTED MICROSCOPE A

200 POWERPerformance Equals$50 to $75 InstrumentAmazing optical qualities, finefocusing, superb definition,clarity! Serviceable construc-tion . . . the greatest micro-cope bargain on the marketl

Try it for 10 days. If

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will take in an Astronomical Telescope you have builtwith your own hands. Your telescope will be worth upto $600. Our kits include: PYREX MIRROR BLANK-PLATE GLASS TOOL-TEM-PERIED POLISHING PITCH-8 ASSORTED EXTRA FINEABRASIVES, ALL IN SHAKER *TOP CONTAINERS (ROUP alsoincluded) FIRST SURFACEMIRROR FOR DIAGONAL -LENSES FOR 1" F.L. EYE- XPIECE-1AGNIFYING LENS.Order Kit according to mirrordHa. desired:

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SO MUCH for SO LITTLE!SIMPLE LENS KITS!-Kits include plainly written, illus-trated booklet showing how you can build lots of opticalitems. Use these lenses in experimental optics, buildingTELESCOPES, low power Microscopes, etc.Stock .#2-W-.1 lens ..................... $1.00 PostpaidStock #5-W-45 lenses ..................... $5.00 PostpaidStock #10-W-80 lenses .................... $;10.00 Postpaid

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1-15/18"1 x 2-15/16"-% thick. Reflects approximately 50% Ir _ Invaluable for laying out drains,

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5September 5) 1952

,,*.feedit toRARABIT

important advantages:1. Uniform formula.Ingredients used in 2. Proper Nutritional Blend. Blendedthe making of Purina Rabbit Chow are into Purina Rabbit Chow are the knowntested for uniformity and nutritional qual- food essentials for rabbit health and vigority. This is important for experimental foode ntialson for youreavwork requiring a uniform dietary history perimental work.through several generations.

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NEW PRODUCTSDL-Alanine anhydride

DL-Alanyl-DL-asparagine. H20

DL-Alanyl-DL-methionineDL-Alanyl-DL-norvaline

DL-AlanylglycylglycineDL-Alanyl-DL-phenylalanine

Glycylglycylglycine

allo Hydroxy-D-prolineBenzoyl-L-arginine amide

DL-Bromopropionyl-D-asparagine

DL- BromopropionylglycylglycinneDL-Bromopropionyl-L-tyrosineChloroacetyl-DL-alanineChloroacetyl-DL-phenyla Ianine

SCIENTCE, Vol. 116

I

6

i PTON_LABORATORY AND RESEARCH MICROSCOPE

OF HIGHEST PRECISION

MODEL W

Truly the most COMPLETE and VERSATILE microscope of its kind.In fact, there is so much to say about this magnificent new instrument,that only a booklet can begin to list its many features and advantages.You are invited to write for your free copy immediately . . . and learnwhy we take justifiable pride in presenting the new ZEISS-OPTONLABORATORY and RESEARCH MICROSCOPE MODEL W.

Write for free, detailed specifications

CARtL ZE IS S, INC., 485 Fifth Avenue, New York 17, N. Y.

Guaranteed uninterrupted repair service

September 5, 1952 7

CAN YOUDO THIS?

Copy (1) parts of largedrawings without remov-Ing from drawing board,(2) small diagrams, sig-natures and sketches, or(3) full-page graphs,charts, prints, specifica-tions?

End drudgery of long-hand-copying and proof-reading notes? Contoura-copied maruscripts anddocuments are letter-per-fect, need no checking.

Copy excerpts, or entirepages up to 81/2 x 14",from non - circulatingbooks without luggingheavy volumes to photocopy company?

Make record copies ofresearch notes right fromtest-finding lab note-book, longhand memos,sketches, projected rat-ings and verified read-ings?

YOU CAN WITH A NEW

-Po444/a PHOTOCOPIERTRULY PORTABLE! Only four pounds; fits easily

in briefcase or desk drower. Use it anywhere! COPIESANYTitNG written, printed or drawn-up to 8½t" x14"4` _ kar copies only 7#1 "Conteura'."unique cushion reproduces tightly bound pages despitecurved binding! NEEDS NO DARKROOM; make ex-posures under normal artificial light; develop prints,at leisure, in standard photo chemicals. ELIMINATESDRUDGERY and inherent error of longhand-copying,typing and proofreading! Users everywhere say "Con-toura" affords time and money savings they neverthought possible. MODELS AS LOW AS $39.00

WRITE FOR FREE FOLDER TODAYF. G. LUDWIG Associates

30 Pease Rd. Woodbridge, Co"n.

For extending the use and spectral accuracyof Colorimeters, Spectrophotometers, FlamePhotometers, Fluorometers, Spectrometers andsimilar instruments.Farrand Interference Filters enable isolationof narrow xegions of the spectrum and therebyafford optimum selectivity. Their cluceltet Dp-tical qualities provide high transmission. Theyare permanent to normal atmospheric condi-tions-not affected by heat because radiation,which is not transmitted, is reflected-notabsorbed.

Bulletin N. 800 en eoqestIPEECISION OPTICS, ELECTRONIC]AND scOUnc NSTUSMENTS_

-~~~~I :SCIENCE, Vol. 116

Section TOUGHEST MaterialsIncluding Plastics, Hardwood,

Undecalcified Bones, Metals, etc.

with

JUNG'S MICROTOME

MODEL KDesigners of PrecisionMicrotomes since 1872.

For details write:

Wm. J. HACKER & CO., INC.82 Beaver StreetNew York 5, N. Y.

I

8

Imaes up to 10 feet acrosseven under oil-immersed objectives

Because of the virtually solar intensity of the Scopi- mey vcon's high-pressure mercury arc, you can project sharply Tb. tete- idetoiled images up to ten feet across even under oil- remar&a*iy stimmersed microscope objectives. The light's white color neitrwaddemonstrates the various biological stains to their best Oisk.rs.,advantage.

The Scopicon is highly adaptable- can be usedwith equal convenience for small-group study in a nor--malty lit room, or for exhibition to large groups in adarkened auditorium. Let us send you the brochuredescribing this versatile instrument.

The Scopiconhigh-pressure

40 mercury arclamp.

micro-projectionI equipmentSCOPICON, Inc. 215 E. 149th ST. NEW YORK 51, N. Y.

September 5, 1952 9

A CLEAR, UNDISTORTED VIEW

OF THE SPECIMEN IS

WITH

These popular rectangular jars are pressedin iron molds to provide parallel surfaces forthe sides, both inside and outside, assuringan undistorted view of the specimen.They are American-made . . . clear, de-

colorized glass . . . heavy, sturdy walls . . .

double-annealed . . . and the surfaces arefire-polished planes. The tops are ground true

]

Support Rods fit in the recesses in the jarsand are used to support large firm specimens.

Support Frames fit in the recesses in the jarsand are used for specimens that requirestretching on a frame and for those that re-quire support at the sides as well as at the top.

and provide a wide surface for sealing. Eachcover has a small opening in the cornerthrough which the fluid content can be changedor additional fluid added after sealing.

* *

Made in ten different sizes, as recommendedby the International Association of MedicalMuseums. Write for descriptive literature.

NOTE TO CHEMISTRY TEACHERS: They makeexcellent lecture jars for big rooms.

IMMEDIATE DELIVERY FROM STOCK

Complete stocks of loboratory instruments, apparatus, reagent chemicals,furniture, and supplies at PITTSBURGH, NEW YORK, ST. LOUIS,WASHINGTON, MONTREAL and TORONTO. For more informationwrite: Fisher Scientific Co., 717 Forbes St., Pittsburgh 19, Pennsylvania.

FISHER ¢}SCIENTIFICAmerica's Largest Manufacturer-Distributor of Laboratory Appliances and Reagent Chemicals

SCIENCE, Vol. 110,

I

IF-EA ..' ",;;'I

10

I'll

I r-1,IF'SK R " A

I

Adventurers

in Research..

Dr. Clinton R. HannaSCIENTIST-INVENTOR

His gun stabilizer revolutionized tank combatduring World War II. He enrolled inWestinghouse Graduate Student Course rightafter graduation from Purdue University in1922. He advanced rapidly to head of Devel-opment Division in 1930, manager of Electro-mechanics Department i}> 1937, and AssociateDirector of the Research Laboratories, hispresent position, in 1944.

Where human muscles and reflexes aren't quite upto the job, the electromechanical regulator can doit many times faster and more accurately. Proofof that is in the career of Dr. Clinton R. Hanna,who has developed a whole family of these devicesin his 30 years with Westinghouse. It was hisgyroscope-controlled gun stabilizer that duringWorld War II enabled Allied tanks to fire accu-rately even when traveling over rough terrain, andhelped swing the tide of battle against the enemyin Africa. When heavy seas sent ship-based radarantennas bobbing erratically, Dr. Hanna designeda system for stabilizing them in the roughestweather.The soft-spoken, 51-year-old Westinghouse sci-

entist has some 100 patents to his credit in thefield of regulators. One of his earliest was adevice for controlling the speed of steel mill rollermotors. Strangely enough, it was this device whichled a visiting Army officer to wonder if the sameprinciple could be applied to stabilizing tank guns.

Dr. Hanna thought it could and proceeded toprove it.

Quiet and methodical, the Westinghouse scien-tist likes to probe for new and difficult applica-tions in his field, isn't swerved by the failure ofprevious searchers. to come up with the rightanswers.

Dr. Hanna's latest achievement is the devel-opment of an- automatic pilot with unlimitedmaneuverability.

These are but a few of the high lights in thecareer of "Clint" Hanna, adventurer in research.The larger picture should certainly include manyother contributions, mainly those that have aidedin the improvement of numerous Westinghouseproducts that feature electrical control and regu-lation. They make it abundantly clear that it isthe know-how and experience of scientists likeDr. Hanna which are the cornerstone of industrialprogress. Westinghouse Electric Corporation,Pittsburgh, Pennsylvania. G-10228-B

YOU CAN SE SURE ... IF ITSrXestinghouse

September 5, 1952 11

Large stage moves up anddown for finer, faster focusing.

Thele EThe PANPHOT combines permanentlyaligned microscope, camera and lightsource in one convenient unit.

Universal Camera Microscopeq nh o fronyourXX Only the Leitz PANPHOT enables you to switch from

microscopic observation to photo-micrography without moving* ~~~~~front your chair, for it's the only universal camera microscope

with operating parts for both functions right at hand. Changeover from one to the other is fast,simple, dependable. Now available to industrial and technical laboratories, the PANPHOT isa perfect combination of research microscope and reflex camera.The PANPHOT permits the use of transmitted light, reflected light, darkfield illumination andpolarized light. The permanently aligned light source provides a filament lamp for observationand an arc light for photo-micrography.Easy observation of the image to be photographed is provided by a large ground glass in the reflexmirror camera. The camera accommodates 3y4"x 4Y4" plates or cut film for black and white orcolor work.A full range of accessories is available to equip the PANPHOT for every phase of photo-micrography, photo-macrography and for drawing and projecting micro-images.

Write today for information to Dept. SC

E. LEITZ, Inc., 304 Hudson Street, Now York 13, N. Y.LEITZ MICROSCOPES e SCIENTIFIC INSTRUMENTS . LEICA CAMERAS AND ACCESSORIES

SCIENCE, VOL. 116

A

A. H. T. CO. MODEL H-I

A0NALYT ICAL B*A,LAtNCEA dependable, low priced Balance, of simple and durable construction, for use in

educational or industrial laboratories

IMMEDIATE DELIVERY PRICE .... $99.00

ANALYTICAIL BALANCE, A. H. T. Co. Model H-1. An improved execution of a time-tested, simplified design, without drawer in base, intended for use in industrial or educationallaboratories for quantitative analysis. Especial attention has been given to the design of thebeam, beam support, stirrups and stirrup rests so that erecting and cleaning can be accom-

plished quickly and with minimum danger of damage to delicate parts.

Sensitivity-1/lOth mg with full load. Change of weight of 1 mg on the pan deflects the pointer on the scale at least 2V/2divisions with full load.

Capacity-200 grams in each pan.

Case-Of mahogany, with counterpoised front door, circular level and leveling screws, without drawer in base. Overalldimensions 16'/2 inches wide x 16 inches high x 91/ inches deep.

Beam-Of hardened aluminum, 6 inches long, with oxidized black finish. Graduated in white on both sides of centralknife edge from 0 to 5 mg in 1/10 mg divisions, using a 5 mg rider.

Knife Edges and Planes-Of agate throughotut.Pans-Of Duralumin. 2½2 inches diameter.Arches-Of Duralumin, height 7'/2 inches, spread 4 inchets.

1812. Balance, Analytical, A. H. T. Co. Model H-1, as above described with two 5 mg aluminsim ridersbut without weights .................. ' 99.00

5%,o discount in lots of 6; 10%r discount in lots of 12 or more.

ARTHUR H. THOMAS COMPANYLABORATORY APPARATUS AND REAGENTS

WEST WASHINGTON SQUAREPHILADELPHIA 5, PA.

Teletype Services: Western Union WtTX and Bell System PH-72

AI

13September 5-, 1952

LBIX"GEESI'ALIFCEEXPE~~~~~~~~~~ I NEN~~~~~~~

BAUSCH & LOMB

LABORATORY

M ICROSCOPES

Frictionless Dynoptic design reduces wear...gives you unequalled focusing ease ...

adds many years to the life of your Bausch & LombLaboratory Microscope. Entire fine focusingsystem floats on ball bearings and rollers...never binding, never drifting out of focus.

To this, and the many other long-lifemechanical features, is added the world's finest

optical system, resulting inthe world's finest laboratory microscope.

sFft4f for FREE DEMONSTRATION and LITERATURE. See for your-self how Bausch & Lomb Dynoptic Microscopes out-perform any labo-ratory microscope ever made. Bausch & Lomb Optical Co., 642-30St. Paul St., Rochester 2, N. Y.

SCIENCE, VOL. 116

e Io] t JIL-