Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~II~~~~~~~~~~~~~~~' 1 1
HIGH on the list of conveniences which theType E offers to users of sensitive galva-
nometers is freedom from frequent "spot chasing."
In addition to the large, primary light spotwhich travels along the 100 mm scale with fullgalvanometer sensitivity, there is a smaller,brighter secondary spot.
Because a given voltage moves the secondaryspot only one-tenth as far as the primary, theeffective length of the scale is increased to 1000mm. So you actually get an approximate read-ing of any deflection which would appear on a fullmeter scale with a conventional lamp and scalegalvanometer. -
Probably even more important is the fact thatthe secondary spot is so bright and moves soslowly-one-tenth as fast as the primary-thatwhen it does shoot off the scale you usually seeit go. You know immediately in which direction
you must correct to bring the circuit to the bal-ance point. You seldom lose both spots socompletely that you have to chase in both direc-tions to discover the unbalance.
For further information, write to Leeds &Northrup Co., 4926 Stenton Ave., Phila. 44, Pa.
CHARACTERISTICSSensitivity Nominal Nominal Resistance, Ohms
List No. per mm Period. External Criticalscale division Seconds Damping System
2430-a 0.5 mv 3 50 17
2430-c 0.005 ma 2.5 400 25
2430-d 0.0005 ma 3 25,000 550
M J~Rgn ERW-W NV - RU* *UV^ mu VUR 5 nu&. .WWN * La I*o|wHEAT-TREATING FURNACES
Jril. Ad ED22(5a)
-715- -7K-75L.- m m.- An M EEL -AM.
"WAMROamd,- emwrniemlrmm . AirmMATIC e-amr"RA .'TCLRMKTrna
AMINO ACIDS
Amino acids, the nitrogenous components of proteins, are of vitalimportance to adequate growth, maintenance and repair of tissue.As a service to nutritional research, GBI offers the followingproducts in convenient-sized packages at an economical price:
DL-alpha alanineBeta alanineL-asparagineDL-aspartic acidL-arginine monohydrochiorideL-cystineL-cysteine hydrochlorideL-glutamic acidGlutamineGlycineL-histidine monohydrochlorldeDL-homocystineHydroxy-L-prolineDL-isoleucine
DL-IeucineL-leucineL-lysine monohydrochiorideDL-methionineDL-norleucineDL-ornitlineDL-phenylalonineL-prolineDL-serineDL-threonineL-tryptophaneDL-tryptophaneL-tyrosineDL-valine
Write for our Descriptive Pre List for complete infor-mation on diet materials, crystalline vtamins, jmicrobio-logical media and miscellaneous biochemicals for research.
GENERAL BIOCHEMICALS, INC.60 LABORATORY PARK CHAGRIN FALLS, OHIO
R~. UA Pot. CM.
1 1111111111!1t1t11111111ll 1 ]]111]]1SCIENCE, September 24, 1948, Vol. 108 1
1 1 1 1 1 1 1 1 1 1 1 1 1
Vol. 108 No. 2804 Friday, September 24, 1948
CONMTIE MTS
Address of the President of theUnited States ... .......................... 313
The One World of Stars:HarlowShapley ............................. 315
News andNotes ............................ 322
Technical PapersThe Quantitative Theory of Autoradiography
Illustrated Through Experiments With p32in the Chick Embryo:Herman Branson and Louis A. Hansborough 327
Crystalline Serotonin: Maurice M. Rapport,Arda Alden Green, and Irvine H. Page ............ 329
The Action of Ryanodine on the ContractileProcess in Striated Muscle:
G. A. Edwards,etal ..................................... 330
The Homing Tendency of Shad:Edgar H. Hollis ......... ............................ 332
Effect of Antiserum and Prolonged Cultivationon the Agglutinative Characteristics of aType I Meningococcus:
DorothyNeuhof Naiman ....................... .............. 334
The Inactivation of Invertase by Tyrosinase:Irwin W. Sizer.......... 335
Mammary Carcinoma in Female Rats Fed2-Acetylaminofluorene:R. W. Engel and D. H. Copeland 336
In the LaboratoryA Simple Micro-Beaker for Use With theBeckman pH Meter (Model G):Victor H. Dietz 338
A Rapid Method for Preparing DDT in theLaboratory: Joseph M. Ginsburg 339
Radiocardiography: A New Method for Study-ing the Blood Flow Through the Chambers ofthe Heart in Human Beings:Myron Prinzmetal, et al .340
Book ReviewsPrinciples of jet propulsion and gas turbines:M. J. Zucrow.Reviewed by Howard S. Seifert 342
Advances in military medicine:C. Andrus, et al. (Eds.)Reviewed by Morris C. Leikind 342
(Cover photo by Science Service, Inc.)
Science, a weekly journal, In published each Friday by theAmerican Association for the Advancement of Science atThe Business Press, Incorporated, N. Queen St. and McGovernAve., Lancaster, Pa. Founded in 1880, it has been since1900 the official publication of the AAAS. Editorial and Ad-vertising Offices, 1515 Massachusetts Avenue, N.W.. Wash-ington k D. C. Telephone, EXecutive 60 or 01. Cableaddress, SCIMAG, Washington, D. C. Entered as second-class matter at the Post Office at Lancaster, Pa., January 13,1948, under the Act of March 3, 1879. Acceptance for mail-ing at the special rate postage provided for in the Act olFebruary 28, 1925, embodied in paragraph 4, Bec. 538. P. Land R., authorized January 13, 1948.
Articles offered for publication should be sent to the Edi-tor. The AAAS assumes no responsibility for the opinionsexpressed by contributors. Membership correspondence forthe AAAS should be sent to the Administrative Secretary.Annual subscription, $7.50; single copies, $.25: foreign
postage (outside the Pan-American Union), $1.00 extra;
2
Canadian postage, $.50 extra. Remittances and orders forsubscription and single copies should be sent to the Circula-tion Department, AAAS, North Queen Street and McGovernAvenue, Lancaster, Pennsylvania, and 1515 MassachusettsAvenue, N.W., Washington 5, D. C. Claims for missing num-bers will not be allowed if received more than 60 days fromdate of issue. No claims allowed from subscribers in CentralEurope, Asia, or the Pacific Islands other than Hawaii or be-cause of failure to notify the Circulation Department of achange of address or because copy is missing from the files.Change of address. Four weeks notice is required for
change of address. This should be sent to Science, 1515Massachusetts Avenue, N.W., Washington 5, D. C. Whenordering a change, please furnish an address stencil labelfrom a recent issue. Address changes can be made only ifthe old as well as the new address is supplied.The American Association for the Advancement of Science
also publishes The Sceintific Monthly. Subscription rateson request.
SCIENCE, September 24, 1948, Vol. 108
Mildred Atwood F. A. Moulton
Ating Editor Advertising Manager
Publications CommitteeFarrlngton Danies, John E. Flyn, Kirtley F.
Mather, Walter B. Miles, Malcolm H. Soule.Steven M. Spencer
LARGER FREEFAST
provide more forlaboratory uses
F HIGH VACUUM-.05 Micron GUARANTEED
AIR CAPACITY- 33.4 Liters Per MinutePUMPING AT ALL PRESSURES
OIL REQUIRED650 ml. Duo-Seal Oil
OPTIMUMOPERATING SPEED300 Revolutions
Per Minute
DUO-SEAL VACUUM PUMPMotor Driven
Produced by skilled workmen with manyyears' training in designing and buildinghigh-grade vacuum pumps. Every pumprigidly tested.
r 1~~M M E D I A T ES H I P M E N T
* CONTINUOUS OPERATION
* DEPENDABLE RESULTS
* QUIET RUNNING
* LONGER LIFE
W. M. WELCH SCIENTIFIC COMPANYEstablished 1 QRn
1515 SEDGWICK STREET, DEPT. E CHICAGO 10, ILLINOIS, U.S.A.Manufacturers of Scientific Instruments and Laboratory Apparatus
SCIENCE, September 24, 1948, Vol. 108 a
Completewith Motor
.t
oazKZIvUaneWU * REV
MODEL 0A lightweight, inexpensiveopaque projector specially de.signed for projection to smallgroups.
MODEL 0A2A combination opaque andslide projector that takesopaque material and standardslides. Can be adapted to 35mm strip film and 2" x 2"Kodachrome slides.
MODEL OA1Incomparable performance isobtained from this excellentopaque projector for 61"4 x6¼" copy.
g.
MODEL OA3An opaque projector that pro.jects full 8½" x 11" pages inmagazines and books, maps,and other large size material.
SCIENCE, September 24, 1948, Vol. 1084
Y'if1,
Twice every minute the TECHNICON PipetteWasher completes its syphon-cycle .. . seven surg-ing gallons of water to loosen and dislodgeclinging residues. Wastes are then literally sweptout of the pipettes by the violent suction set up dur-ing the brisk ten-second emptying phase.
Only the Technicon washer offers such rapidity andthoroughness, delivering in six cycles a full basket-load of immaculate pipettes (capacity 200 of 1 mlin 1 OOth's, up to 1 8" long). The stainless steel
basket, proof against corrosive reagents, carriesits load of pipettes undisturbed through everystage: cleansing, washing and drying. Requires noindividual handling, no shifting from container tocontainer, practically eliminates breakage andchippage. A must for the busy laboratory: let ussend you Bulletin #6150 giving particulars.
T H E T E C H NI CON COM PANY215 E. 149 St., New York 51, N. Y.
1.'No fuss or muss . . .pipette washing canbe as easy as this-~~~~
omiocP74Z C PIPETTE WASHER
SCIENCE, September 24, 1948, Vol. 108 5
(it) Drect-Readiing-Decimal indico-tion. All counts ore reod directly G E I Cwithout tedious interpolation.
Scale of 1000-Electronic scaling A Geiger-2 provided by three compact, inter- able in th
changeable plug-in units. Built-inregister records thousands. indication
Total Weight 10 Pounds - Un- strument cmatched portability and conven- Reliabiience in handling achieved throughradically new design. engineerir
Automatic Operation-Three throughotflexible plug-in accessories provide -
4 automatic scaling for predeter- atron labcmined time interval and predeter-mined number of couvts. them. AnNew High Voltage Supply-Ad-
5 justable from 100-2500 volts, elec-tronically regulated for stableoperation. Accurately metered andeosily adjustable.
6 Plug-in Units-Assure rapid test-ing and convenient replacement ofsubcomponents.
Direct Decimread without irindicated abo
SUPERIORITY
[KELEY DECIMAL
5ER-MULLER SCALER
*Muller scaler of radically new design is now avail-e Berkeley Decimal. Compactness, direct-readingand automatic operation are combined in an in-
offering many special advantages.[ity, a primary consideration, is assured in theng of the Berkeley Decimal. Its developmentut followed the needs of scientists in leading radi-)ratories, obtained from close consultations withd, this most advanced scaler is reasonably priced.
i1n Indication-Att countsinterpolation. (5867 counts)ye.)
Decimal Counting Unit-Selt-con-tained plug-in component, for conven-ient testing, servicing and replacement.
Send for full informationin Bulletin BDS-100
tSIXTH:: AND NEVINi- AVENUE * RICHMOND, CALlF-
SCIENCE, September 24, 1948, Vol. 1086
j
Since 1932
laboratory
Animal Cages
lby
Distinctive Equtment tomodernize the laboratory
Biological tests can be made much more ac-curately and conclusively when animals arekept in cages such as these. BUSSEY cages aredesigned for the very ultimate in cleanlinessand ease of servicing, making for a far moresanitary and agreeable laboratory.
There are several types of cages, each for aspecific purpose, and one all-purpose model,illustrated above, designed for guinea pigs,hamsters, rat colonies, small rabbits and cats.The illustration below shows our top openingmice and rat cage also made in a front openingmodel for rats. Also available is a specially builtcage for rabbits.
Racks are designed for each type of cage andare constructed so that cages are suspended,with dropping pans as separate units, an ex-clusive BUSSEY feature. At no time are animalsin contact with their excreta, an importantfactor in controlled experiments
All cages and racks are of the very finestelectric wdded construction finished in pedihigh perature `Silicone" iluminum enamelresistant to strong cleansing and disinfectingsolutions, and their beautiful streamlined ap-pearance will add much to any laboratory.We invite you to write us for literature and
prices or if you have a special. equipmentproblem our engineering department will beglad to cooperate with you without cost.
SCIENCE, S1eptember 24, 1948, Vol. 108 I ., 7
-7- m
* Revolutionary design and con-struction introduces new high stand-ards of optical and mechanical performance.
WIDER FIELDSSTURDIER MECHANICAL CONSTRUCTION
HIGHER EYEPOINTDUST-PROOF NOSEPIECE.. Sealed-in Prisms
WRITE for complete informa-tion and a demonstration. Bausch& Lomb Optical Company,642-V St. Paul St., Rochester , ;2, New York.
v on * ^ 7~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"diinlyHeA_ [ r u~. ~~~~~~~~~
FSCIENCE, September 24, 1948, Vol. 1088
Related Documents
