Time-lapse motion picture in Ha light of 130,000-milehigh solar prominence rising 15 mi./sec., made inHarvard College Observatory Coronagraph on 35mm.Type 103 H-Alpha Kodak Spectroscopic Film.

'present your paper in movie formHE NEXT lIME you have a complicatedscientific paper to present . . . when

your research, your- findings, are of a naturedifficult to explain clearly and simply ...

you may want to use motion pictures.Why motion pictures?Because their combination of pictures,

action, and color can show complicateddetails, methods, and equipment withunique simplicity and clarity.

SCIENTIFIC FILMS. .. another important function of photography

Because with high-speed and time-lapsemethods, they can show movements thatare otherwise much too fast or too slow forhuman observation.

Because, in short, motion pictures willenable your colleagues, your students, thepublic, to see your work and findingsexactly as you saw them.Eastman Kodak CompanyRochester 4, N. Y.

9

0 0m

Reg. U.S. e.

CR s TA L L I N EVITAMINS

Essential as Standards andSupplements for Biological ResearchAlpha CaroteneBeta CaroteneCarotene(90b-1Oa)Vitamin AAscorbic AcidAlpha TocopherolBiotinCholine Chloride

Ca PantothenateInositol2-Methyl Naphtho-quinone

NiacinNiacin Amidep-AminobenzoicPyridoxine HCIRiboflavin

Thiamin ChlorideConvenionly Poekod-Economieally Priced

Write for Price List No. 677

Ee I:± 1[141s'I[± NI~[

60 LABORATORY PARK CHAGRIN FALLS, OHIO

tVITAMIN TEST CASEINj

for Biological Assays and ResearchFat and water soluble vitamins are removedby several thorough extractions with hotalcohol. This process, which requires fivedays of special treatment, provides a prod-uct of exceptional purity and uniformitymaking it ideally suited for use in a widerange of experimental diets. It has been theVitamin Test Casein of choice of manylaboratories for the past ten years.For other GBI diet materials andsupplements write for Booklet No. 677

GENERAL BIOCHEMICALS, INC.S0 LABORATORY CHAGRIN FALLS,

PARK iIsD OHIORg.U.S.A Pot. Of.

'I"'Uk','

ALBINO RATS

CF WISTAR STRAIN

Developed after many years of careful inbreed-ing. Part of this colony is maintained on an op-

timum diet for experimental research. Anotherpart, for use in biological assays, is fed a VitaminD deficient diet.

Cl Wistar rats have been the animal of choicein a number of laboratories for many years. In-creased production enables us to offer them to a

larger number of customers.

I

Klett made * * .

lass Absorption Cells

Fused under high temperature with acid alkali and othersolvent resisting cement. Optical fiat walls Many stock sizes

Special requirements made to orderSole mafaetnre in the United States of fused Electrophoresis cells

Makers of complete Electrophoresis Apparatus-KLETT SCIENTIFIC PRODUCTS-1

Kiett-Snmmerson Photoelectric Colorimeters. Colorinostena, Nephetometers. Fluormetets. B10 Colorimeters, Blec-trophoresis Apparatus. Glass Standards. Klen Reagents

Klett Manufacturing Co.179 East 87th Street, New York, New York

10

New REINHOLD Books

ADVENTURES INMAN'S FIRST PLASTIC

THE ROMANCE OF NATURAL WAXES

By NELSON S. KNAGGS

A story of adventure and discovery in one of theoldest and most intriguing of man's searches fornew materials. The author relates his experiencesand describes the entire panorama of the historyand applications of natural waxes through thecenturies. There are chapters on Cauassfi Wax,Carnauba Wax, Candelilla Wax, Spermaceti Wax,Shellac Wax, Chinese Insect Wax, Ouricuri Wax,Esparto Wax, Beeswax, Ozokerite Earth Wax,Montan Wax, Paraffin Wax, and the Micro-crystal-line Waxes.

440 Pages 100 full-page photographs $6.75

RE

SOILLESS GROWTH of PLANTSBy CARLETON ELLIS and M. W. SWANEY

Second Edition, Revised and Enlarged

by TOM EASTWOOD, Olericulturist, Lago Oil and

Transport Co. Ltd., Aruba, Curacao, N. W. 1.

A thorough treatise on all aspects of this important

development in agricultural science, by an authority

who has been in charge of one of the largest and most

successful commercial installations in the world.

Includes nutrient solution formulas, operating data,

construction details and all pertinent information.

283 Pages Profusely illustrated

Send Todayfor New Free Catalog "Let's Look It Up" (over 200 titles)

INHOLD PUBLISHING CORPOR330 West 42nd Street, New York 18, N. Y.

$4.75

ATION

*..TO HELP YOU

LABORATORYEQUIPMENT

.t'These Castle catalogs des-cribe all the Castle precisionequipment for the bacteri-

* ~~~~~ological laboratory... inl- . 4A4.TLcubators, baths, sterilizers,ovens ...with full details ~ I1'of design and service. V'4l1.1'R~ nUse the attached coupon TMB'J111U1I

for your free copies. No ..APPARATUS obligation.

- I WILMOT CASTLE CO.~~~ ~ ~ ~ 122University Ave., Rochester 7, N. Y.

_.' ~< I Please send methe bacteriological catalogs. I understandthereis no obligation i

Name.----.-------.-,------- ,--,-------- ----------------------------------------------

iCompany......... ,,,,,, ,,,,--p 1 0 |I Address. -* .i. , _. .,..... ,. A*

___ |City,,,_,,..Sae.---.--.-- - - ---...Stat

11

a

F-_A1 _c __

CrTIMIi11 ATrOM2IE EVE M L* AdW-

Model 461* Constant wave form inde-

pendent of stimulusstrength and frequency

0 10 freq uencies from 0.5 to100 pulses p.s.

* Single-stimulus push-button control

* 3 voltage ranges: 0-10, 0-25,0-250

* Neon light signals eachpulse

* Centralized control fromsloping panel

* Operate from standard 110volt 60 c. power circuit

$61.50 F.O.B. Boston

The Electrodyne Stimulator is primarily designed to af-ford elementary physiological laboratories a generator ofcontrolled electric pulses which may be applied to thestudy of nerve and muscular reactions to changes of stim-ulus current and frequency.

The wave form of the generatedpulse rises rapidly to a maximum,followed by an exponential decayover a period of 0.3 milliseconds.

The Electrodyne Stimulator is usedin theElementary PhysiologyCourseat Harvard University in connectionwith the study of: "threshold"; use

A synchronized pulse for a standardsignal magnet is generated by a sep-arate circuit without interferencewith the stimulus characteristic.

of cathode ray oscilloscope; frogsciatic; human "motor points"; tur-tle heart vagal stimulation, ven-tricle tetanization; etc.

Stimulator Model 461 is described in Bulletin 187. Specifications of the

Electrodyne Research Stimulator are given in Bulletin 187-R.

I 11 H o C + l tTI 0 COMPANY 899 Boylston StreetJ.Boston 15, Massachusetts

For Spectrochemical Analysisin Biology and Chemistry

and for Instruction in Optics

The New Jaco Junior Spectrograph@ $1200.00

This 3 Meter Replica Grating Spectrograph offers dispersionand resolution hitherto unavailable in an inexpensive replicagrating spectrograph. The instrument covers a range of 2200A-7800A on a 20" film at a dispersion of 10.9A/mm. The Fetriplet 3099.94,3100.33, 3100.67 can be resolved readily. Thesame quality construction employed in the Jaco Research 21'Spectrographs has been maintained throughout, so that theinstrument is suited for serious analytical work.

Research models with adjustable wavelength range are alsoavailable.

JARRELL-ASH COMPANY165 Newbury Street Boston, Mass.

12

1000 SAMPLES in 33 INCHESof SHELF SPACE...!

Here's the answer toa Big Problem

CONVENIENT, COMPACT,SAMPLE STORAGE SETS

for indexing and storing referencesamples:-100 samples in 3M inchesshelf space; 1000 samples in 33 inches.MODEL "A" SET, shown herestores 100 samples (about 10 ml. vol-ume) in 3*' shelf space.

ONE THOUSAND SAMPLESwithin 33 inches of shelf space

Choice of 4 ModelsComplete with vials, corks, or caps.... gummed labels and largeindex cards.A.... Contains 100 4i'x i'vials. $3.25 each. $30.doz.A-SC.... Same as "A", but with screw-capped vial. $5. each,

$48. doz.B.... Contains 50 21' x i' vials. $2.50 each, $24. dos.C... Contains 50 31' x 1' vials. $3.50 each, $36. doz.

Write Dept. S. Orders filled Unmediately.Hydrion (short range and special), pH test papers.

Write for latest information.

R. P. CARGILLE 118 Liberty Street

New York 6, N. Y.

AAAS iUm SYMPOSIA

A considerable fraction of the Symposium Volumes and Research Conferencespublished by the AAAS have been exhausted by orders not only from librariesand from specialists in their respective fields, but also from foreign librariesand scientists. The titles remaining in print are shown below with prices.

Two new volumes are in press, Approaches to Tumor Therapy, a comprehen-sive discussion by more than 6o participants, which will appear in the nearfuture; and The Rikettsial Diseases of Man, a survey of an important groupof serious infectious diseases which have recently become important healthproblems.

Title PricesMembers Non-members

Tuberculosis and Leprosy ............................... $2.. 50 $3.00The Migration and Conservation of Salmon .. 2..oo i. 50The Genetics of Pathogenic Organisms...... 2..oo 2.. 50Blood, Heart and Circulation ............. 3.00 4.2.5Human Malaria.......... .............................. 00 5.00Liebig and After Liebig-A Cntury of Progress in AgriculturalChemistr............................................o.2-5 3.00

Aerobiology ........................................ 3.50 4.00Relapsing Fever........................................50 3.00

Fluorine and Dental Health....................-50 3.00MammaryTumors in Mice ................. 3.50 4.00Cancer.4................................................ 4.00 4.50Both Mammary Tumors and Cancer, on one order .......... 6.2X5 7.2.5Dental Caries and Fluorine .............................. 3.00 3.50

7- x IO', double column, illustrated, cloth bound

Send orders with correct remittance to:

Publications Division

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE

1515 Massachusetts Avenue, N. W. Washington 5, D. C.

13

A complete line for clinical laboratories de.voted to all branches of chemistry, bacteri.-,logy, hematology, and parasitology. Testedand checked in our own clinical laboratories.Purity warranted. Our facilities assure promptshipment of large or small orders. Inquiriesinvited.

COMPLETE CATALOGReagents catalogued alphabet. CiMd40Vically-also according to sub. A', dir/¢jects and techniques plus med.ical reference guide. Catalog idecomprises full line blood test.ing sera includin anti-Rh,/ 4 -anti-M and anti-N, also re. t4*agent* for Wassermann, Kline, /Il,,

and Kahn tests. Write for your / ,tcopy. FREE ON REQUEST. /h S

14

A new development

DIRECT READING BRIDGE

for observing variations in

ELECTROLYTIC CONDUCTIVITYEspecially suitable for studies of blood conduc-

tivity.

We also manufacture Multiple Channel Electro-

encephalographs with three tape speeds for re-

cording brain, heart, and other muscle potentials

a perfected direct-recording Electrocardiograph. .

Variable Frequency Stimulators. Cathode Ray

Electromyographs . . Impedance Plethysmographsand other instrumentation for physiological re-

search.

RAHM INSTRUMENTS INC.12 West Broadway New York 7, N. Y.

MAGNIFIERFolding, Doublet, lOx

TITH magnifiers of all kinds soaring in price,W here is an opportunity to procure a qualityinstrument at exceedingly low cost.

oUBLE-convex lenses, carefully mounted inLD aluminum housing, giving undistorted max-imum field, very light in weight. Excellentmagnifier for laboratory and field work.No. 1874 MAGNIFIER, .............. 4.00

10% discount in lots of 5 or more

EST. 1919

PRODUCT

New York Scientific Supply Co.General Supplies for Chemistry and Biology

28 West 30th Street New York 1, N. Y.4

40m6MOW~iots mhe pid au

PHlOTOGRlAPHRY IN SCIENCtECompetition & Salon

Purpose and Nature. The Photography in Science Exhibition,sponsored jointly by the Division of Graphic Arts of THESMITHSONIAN INSTITUTION and THE SCIENTIFICMONTHLY, is designed to bring together the various techniquesof photography used by scientists in all fields of science and therebyextend its possibilities for development as a basic tool in researchand teaching. While unusual contrasts and pleasing compositionare important factors in other fields, the utilization ofnew techniquesof photography for the discovery or presentation of scientific data,scientific principles, and the dissemination of these ideas to allscientists will be stressed as the purpose of this salon. Scientistseverywhere are cordially invited to participate.

Eligibility. Membership in the A.A.A.S. is not required. Scientists actively engagedin teaching at all levels, in research and development, or scientists engaged in privatepractice or consulting, are eligible to submit entries.

Kinds of Prints. The exhibition will be composed of two divisions: Black andwhite and color. Black and white prints may be any size up to i6 x to inchesand color slides or transparencies should not exceed 3 4 x 41 inches.

Dates. Entries will be received in Washington from September 25 to October I5.The accepted entries will be hung in the Smithsonian Institution from November i

to 30. They will then be shipped to Chicago for display at the International ScienceExhibition of the A.A.A.S. from December 26-3 i. At that time awards for the twodivisions will be announced. A selection of the prints will be published in theJanuary, 1948, SCIENTIFIC MONTHLY.

No Entry Fee Required. No entry fee is required, but all entries must be sentprepaid and will be returned express collect at the close of the exhibition.

Information and Entry Blanks. For information and entry blanks write to:

The Editor

The Scientific Monthly1515 Massachusetts Ave., N.W. Washington 5, D. C.

15

-1

R- sAi

Personnel Placement

POSITIONS WANTED

The California Medical Bureau, Agency for scientific andlaypersonnel inmedicine, biology, chemistry, physics and allied sciences, supplies teachers,research workers, laboratory dieners, skilled office help. Prompt service.Registration free. Your patronage respectively solicted. THE CALInos-MNA MEDICAL BUREAU, Agency, Arcade Medical Center, 696 ColoradoStreet, Pasadena 1, California.

Available as graduate dean, department head, or director research: Inter-national scientific reputation. Nationally recognized teacher and lecturer.

Many publications and patents. Created scientific fields, industrial pro-

cesses, laboratory devices broadly in chemistry and physics. Americanwith breadth, originality, ability, integrity and industry. Now directorand consultant. Box 915, SCIENCE.

Botanist: woman, PhD, experienced teacher, desires college position innortheastern or northcentral state. Box 929, SCIENCE.

Employee Ideas. Physicist, ME, fifteen years patent and invention de-velopment. Can organize, develop and manage department. Inventions,P.O. Box 2927, Hollywood 28, Calif.

PhD, Endocrinologist-histologist. BS and MS in zoology. Research andpublications on steroid and pituitary hormones. At present with largeeastern hospital. Desires academic position in university or hospital.Box 930, SCIENCE.

Anatomist: Professor and head of department of anatomy in universitymedical school for the past twelve years; particularly well trained in gross

and neuroanatomy; for further information, please write Burneice Larson,Director, Medical Bureau, Palmolive Building, Chicago 11.

Psychologist: MA, PhD degrees; has specialized in applied phases of psy-

chology; since 1938, professor of psychology and director of research, liberalarts college; for further information, please write, Burneice Larson, Direc-tor, Medical Bureau, Palmolive Building, Chicago 11.

Agronomist. PhD. Experienced in research and teaching. Good knowledgeof biochemistry and colloidal chemistry. Prefer teaching or research. Goodreferences. Box 935, SCIENCE.

Biologist: PhD, age 51. Many years successful college teaching and ad-ministrative experience. General biology, zoology, botany, entomologyvertebrate anatomy, embryology, histology, genetics. Available September.Box 936, SCIENCE.

University or college teaching position in bacteriology, immunology,allergy; also qualified in organic and biochemistry. Number of years ex-

perience, research, some teaching, leading eastern institution. Publications.MS equivalent. Box 937, SCIENCE.

Zoologist: PhD, invertebrates, ecology, botany minor. Ten years experiencecollege teaching. Available September. Location west of Mississippi only.Box 938, SCIENCE.

POSITIONS OPEN

Biochemist for collaborative research on metabolism of the central nervoussystem. Midwestern medical school. Box 934, SCIENCE.

Positions Open: (a) Physicist; PhD, trained and experienced in electricaldischarge in gases; advantageous if experienced in high frequency excitation

of gaseous tubes, determination of Townsend coefficients; university re-

search appointment; $400-500. (b) Statistician; large manufacturing com-

pany; middlewestern town of 15,000. (c) Two biochemists and, also, pharma-cologist; research appointments, pharmaceutical company; salaries forformer, 40O0-o5000-for latter, $5000; East. (d) Zoologist; associate or full

professor, to take over general supervision of physiology; southern college.(e) Biochemist well qualified in research; duties involve biologic, chemicaland immunologic problems in allergy; large teaching hospital, eastern

metropolis; $4000-6000. (f) Parasitologist; research group working in

malaria chemotherapy; $4200-5200. S7-3, Medical Bureau (Burneice Larson,Director) Palmolive Building, Chicago 11.

16

Personnel PlacementPOSITIONS OPE'N

Attractive industrial research, production and sales positions for agrono-mists; bacteriologists, chemists; analytical: biological, inorganic. organic,pharmaceutical, physical, chemical engineeis; entomologists; geologists;horticulturists, metallurgists; microscoiuists, 1hartnm( ologists; physicansand surgeons; physiicis;, plani pathologists and physiologists. ChemicalDepartment, Positioni Securing Bureau, lin(c. (Agency) 45 John Street,New York City.

Wanted: Assistant professor of chemistry with PhD degree to teach inor-ganic, analytical, physical; and assistant professor of mathematics, masters.degree minimum. Large teachers college Midwest. Box 922, SCIENCE.

Wanted: Business Psychologist, assistant professor, PhD or equivalent.Write or wire for information to L. S. McLoed, University of TulsalTulsa4, Oklahoma.

Analytical chemist for rock and mineralvanalysis. Salary $3600 to 4800according to qualifications. Bureau of Mineral Research, Rutgers Uni-versity, New Brunswick, New Jersey.

Chemists: Recent graduates or experienced chemists with PhD, MS or BSdegrees wanted for research and development in organic, inorganic, analyt-ical and physical sections at Detroit Research Laboratories or for develop-ment at Baton Rouge manufacturing plant. Excellent facilities and widefield with commensurate responsibilities. Pension and' insurance plans.Give complete details as to education and experience in first letter. Allreplies will be confidential. Address Ethyl Corporation, 1600 West EightMile Road, Detroit 20, Michigan.

Research assistantship: physiology, midwestern university, $2400, chemicalanalysis. Give background, experience and references. Box 932, SCIENCE.

Instructorship in physiology, midwest; $3000. Time and facilities' for re-search. Give training and references. Box 933, SCIENCE.

X-Rays. Position Open. Research assistant, graduate physicist or physicalchemist, for full-time work in the field of X-Rays, crystal structure andrelated problems in physics of metals. Opportunity for tuition-free ad-vanced study in night school. Give full qualifications and salary requiredin letter. Metals Research Laboratory, Carnegie Institute of Technology,Pittsburgh 13, Pennsylvania.

Applications are invited for associate professorship in bacteriology and bac-

teriologist Agriculture Experiment Station. West Virginia University.Address J. G. Leach, West Virginia University, Morgantown, W. Va.

The Market Place

LANGUAGES

Technical Translations made from or into any language: Medicine, Chem-btry, Biology, Engineering, Physics, Metallurgy, plastics and other sci-

ences. We translate manuscripts, articles patents, books, catalogues and

descriptive literature. TRANSLATION & AESANCEH BUREAU, 7 East 42nd

St., New York, N. Y.

BOOKS

Bailey's MAMMALS OF VIRGINIA, 432 pages, 99 illustrations, 1946. 130

kinds recent mammals-man, domestic and wild mammals. List of fossils.Bibliography 758 titles Only publication devoted to Virginia zoology.$5.00. John Wendell Bailey, 27 Willway Road, Richmond 21, Virginia.

Books wanted: Quarterly Cumulative Index Medicus Volumes 31, 32, 33,several copies and other volumes. Box 931, SCIENCE.

B K S SCIENTIFIC and

| TECHNICALLARGE STOCK ALWAYS AVAILABLE

Please State Interests

LONDON: 1I. K. LEWIS & Co. Ltd.136 GOWER STREET, W. C. 1Cables:.Publlcavit: Weatcent: London England

CHARGES FOR CLASSIFIED ADVERTISINGRegular setting 10t a word. Minimum charge $2.50 for each inser-tion. A box number counts as 8 wnrds of the advertismeut (e.g. 25words plus box number equals 3. words). Make checks payableto the A.A.A.S. All insertions must be accompanied by correetremittance and sent to the Adv D)ept A A.A.S. Please addres-.replies as follows: Box number, SCIENCE. 1515 Mass. Ave.. NW..Washington 5. D.C.

The Market Place THE NEW SERIES OF

BOOKSLaMOTTE WATER SOLUBLE

pH INDICATORSWanted to purchase-Scientific Periodicals, sets and runs. Foreign-Domestic. Entire Libraries and smaller collections. WALTER J. JOHNSON, (Sulfon-phthalein) pH 0.2-9.6125 East 23rd Street, New York 10. In Sparkling Crystalline Form

Journals, Periodicals, set and runs. Also whole collections purchased forcash. J. S. CANNER & COMPANY, 909 Boylston Street, Boston 15, Massa-chusetts.

Highest prices paid for scientific periodicals, sets, runs or single volumes.

Libraries or collections purchased for cash. Zeitlin & Ver Brugge, 624

South Carondelet St., Los Angeles 5, Calif.

SUPPLIES AND EQUIPMENT

Amino acids and protein analysis by microbiologic methods. Hydrolysateproblems. Shankman Laboratories, 2023 S. Santa Fe Ave., Los Angeles New, highly purified products, forming instant so-21, Calif. lution with distilled No alkali to be added

Adenine Sulfate, cholic acid, desoxycholic acid, bilirubin, guanine, asparticacid, thymonucleic acid, cysteine cy tosine glucuronic acid, iodoacetamide -no mixing in mortar-no filtering-no waiting.Dougherty Chemicals, 87-34 134th St., Richmond Hill, N. Y. Simply add the proper quantity of the new LaMotteHamster laboratory stock as low as $10.00 per dozen. 1 pair $3.00. Write Indicator to distilled water in dilution flask and afor price list. D. A. Armstrong, 15854 Lindsay, Box 7B, Detroit 27, brilliant solution of maximum sensitivity, stability,Michigan.

and tinctorial powter results.Nomograms, nomographs, alignment charts are synomyns, and our special-ity. Specify degree of accuracy and range of values desired. Free bro-chure. H. D. Ruderman, Time-Saving Computing Devices, 1533 Townsend In ordering specify Water Soluble Indicators.Ave., New York 52, N. Y.

Natural Amino Acids available 1(+) Blanine, 1(+) Glutamine, (1-) Mllade exclusively byHydroxyproline 1 (-) Methionine, 1 (-) Phenylalanine, 1 (-) Proline, 1 (-)Jerine. Write lor list A4. Bois Laboratories, 607 West 43 Street, NewYork 18, N. Y. LaMotte Chemical Products Co.Proline, Artinine, etc.; Biochemicals. Consulting, analytical, manufac- Dept. "H" Towson 4, Marylandturing chemists. Precision analysis of biological materials. H. M. CHEw-ICAL Co., LTD., 144 No. Hayworth Ave.. Los Angeles 36, Calif

Photoelectrie

with Determination

C. P.

is now available in commercial quantities.

Samples and prices will be sent on request

ALSOAdenine and its salts NaphthoresorcinolAdenosine ueleic Acid and its salts

Adenylic Acid Polidase

Cozymase d-Ribose

Fructose Diphosphates I-Sorbose_lutathione ThiothymineGuanine and its salts ThymineGuanylic Acid UracilHypoxanthine XanthineInosine Xanthosine

Write for bulletins describing chemicals in which you are interested.

*Leys, D. Hyperthyroidism treated with methyl thiouracil .

LUMETRON Colorimeter Mod.400

Lancet (London) pp. 248 (6346) 461-464 (April 14, 1945).*Magnusson, P. and gorensen, G. Treatment of hyper-

* Highly accurate pH measurements thyroidism with methyl thiouracil. A cta Med. Scand.Covering the complete pH range 125, 2 (1946)A0 Annilohl&. tn a frpst variatv of n14 nrobifmlavnes7o.

17

W ^ppitcaust: w a area& Varawy us paX pavuruge

While serving as pH meter, LUMETRON MOD.400 is equally suited for all colorimetric and turbid-imetric tests in chemical analysis. Price $143.0095MA An. PHOTOVOLT CORP. New YAork 1 . .Y

Wrile for literature on Photoelectric pH Determination

RESEARCH

EDUCATION

MEDICI NE

BIOLOGY

-COMMERCIAL RADIOACTIVITY CENTERSINSTRUMENTS * ISOTOPE PROCESSING * TRACER ANALYSES . INDUSTRIAL APPLICATIONS * RESEARCH

I N DUSTRY

COMMERCE

M1 NING

TRACERLAB, INC..55 OLIVER STREET. BOSTON 10. MASS.

WRITE FOR BULLETIN MSCRh3INGTHE TRACERLAB AUTOSCALERFOR RADIOACTIVITY SUREMENTS II mI I

MONTHLY PUBLICATION8roc0rIg.SENT FREE UPON REQUEST OIL PROSPECTINGI I OLIROPCTN

18

.

New Wiley BooksULTRAHIGH FREQUENCY TRANSMISSION AND RADIATION

By NATHAN MARCHAND, Electrical Engineering, University Extension,Columbia University; formerly Senior Engineer, Federal Telecommunications Laboratories.

An up-to-date textbook for one-semester courses in the radiation and transmission ofelectromagnetic waves, designed primarily for the electrical engineering student. Its ap-proach, and the mathematics involved, make it especially suited for students at the seniorlevel. The author has made no attempt to cover the complete specialized field of radiationand transmission. Instead, he has concentrated on discussing the basic principles withsolidity of content and clarity of explanation. Chapter headings are: Transmission Lines,Elements of Vector Analysis, Fundamental Electromagnetic Equations, Plane Electromag-netic Waves, Radiation, Antenna Arrays, Wave Guides, Complex Transmission Line NetworkAnalysis.Ready in August Approximately 296 pages 6 by 9j4 Probable price, $4.0O

VECTOR AND TENSOR ANALYSISBy LOUIS BRAND, Professor of Mathematics, University of Cincinntati.

A textbook of unusually broad scope which will serve as an excellent basis for courses invector analysis, tensor analysis, and surface geometry, as well as for a brief course in thefundamental principles of aerodynamics. Important features of this book include: tensoranalysis introduced in three dimensions, for the salke of concreteness, before being extendedto n-dimension; the first full-length treatment of motor algebra, using dual vectors; andl acomplete coverage of integral transformations with applications.Published in June 439 pages 5% by 88 $5.50

ROCK AND ROCK MINERALS SEQUENTIAL ANALYSISBy the late LOUIS V. PIRSSON andADOLPH KNOPF, Sterling Professor ofGeology, Yale University.

The revision of "Rocks and Rock Minerals"makes available a.n entirelv up-to-dateedition of this book, an extraordinarilygood and well-presented source of informa-tion on petrology on the megascopic level.Among the important features are. an im-provedc- classification of igneous rocks, acompletely new discussion of sedimentaryrocks, and a modern treatment of meta-morphic rocks.

Ready in August5% by 8%/

Th irdl Edition.349 pages

Probable price, $3.75

By ABRAHAM WALD, Professor ofMathematical Statistics, (Columbia t(ni-versity.

The first book-length treatment of an im-portant new statistical technique. Calledthe Sequjential Probability Ratio Test, thismodern method has many proven advan-tages over other procedures for testing astatistical hypothesis. It was developedby the author and was used extensivelyduring the war in development. work onmilitary and naval equipment. The bookis part of the WILEY MATHEMATICALSTATISTICS SERIES edited bY Walter A.Shewhart.Published in May 212 pages61by 94 $4.00

John Wiley & Sons, Inc., 440-4th Ave., New York 16, N.Y.

..dy-__

Provide Beth HIGH POWERLAWOE-IELD'

-and both are necessary for inspectionof minute details.

Designed by experts and manufacturedby the same precision methods as SpencerMicroscopes,these magnifiers are noted fortheir large, flat, brilliantly defined fields.

UTILITY MAGNIFIERA 4.5 xDOUBLET giving an extremely

large field, mounted on a horseshoe basethat holds the lens at the proper distance.

HAND MAGNIFIERSMagnifications for DOUBLETS range

from 6 x to 12 x, and for TRIPLE AP-LANATS, from 6 x to 15 x.

American OpticalScientific Instrument'Division

]Bffalo MS, NewYork

1

1i

'L- 1- - % ' 'a ry.

I- 1T - "I

:.: . ... :',. 1

---4.

1-1'41A ...- ..