If the translated journals become self-sustaining, we will take this as an indi-cation of acceptance by scientists. If,.after 3 years or so, the subscription listto any one journal is still very small, wewvill probably take this as an indicationthat we should not continue to supportthe translation of that journal.

In essence, Luts and I are both right;which one is the most right depends onthe subject matter, the need for infor-mation, the quality of particular jour-nals, availability and price of "to order"translation, and other similar details.

RALPH E. O'DETTFNational Science Foundation,Washington, D.C.

which written permission was obtainedto perform the test.

Reports in the literature and our ownresults do not seem to indicate that trans-abdominal amniocentesis is a dangerousoperation in human beings; however, fur-ther evaluation is necessary before theprocedure can be recommended for gen-eral use.

FLI.NRY M. PARRISHFRANK R. LOCK

MARY E. ROUNTRFFDepartment of Obstetrics andGynecology, Bowman Gray School ofMedicine of Wake Forest College,[lfinston-Salem, North Carolina

EQUIPMENT NEWSThe information reported here is ob-

tained from manufacturers and fromother sources considered to be reliable.Science does not assume responsibilityfor the accuracy of the information. Allinquiries concerning items listed shouldbe addressed to Science, Room 740, 11WV. 42 St., New York 36, N.Y. Includethe name(s) of the manufacturer(s) andthe department number(s).

*DELAY GENERATOR consists of a triggergenerator, a delay generator, and a regu-lated power supply. The trigger genera-tor furnishes a standard negative pulse

Transabdominal Amniocentesis

I should like to point out a problemin ethics involved in a recent paper byParrish, Lock, and Rountree [Science126, 77 (1957)]. The authors report on50 cases of transabdominal amniocen-tesis in normal pregnant women. Men-tion should be made of the disregard ofpatients involved in trying this proce-dure on these cases in view of the highincidence of congenital abnormalitiesfollowing amniocentesis in mice reportedby Trasler et al. [Science 124, 439(1956)]. Although no fetal trauma wasreported, this was an experiment, andthe result might have come out the otherwvay. Were the patients aware of thedangers?

LUCILLE MOROWII /..559 Avon Drive, Orange, Connecticut

In respolse to Lucille Morowitz. whoquestioned the ethics involved in ourperforming transabdominal amniocente-sis in normal pregnant human beings"Science 126, 77 (1957)l after Trasleret al. [Science 124, 439 (1956)] had re-ported congenital malformations in micefollowing a similar procedure, we wouldlike to offer the following considerations.

First, Rivett [Am. J. Obstet. Gynecol.52, 890 (1946)] did not observe amnio-o-entesis harmful to the mother or childin 50 human cases of polyhydramnios,nor did Dieckmann and Davis [Am. I.Obstet. Gynecol. 25, 623 (1933)] noteany deleterious effects produced by theprocedure in 25 normal human patients.Second, our work was completed during1955, before the publication of Trasler'sreport. Also, Trasler's work was done onmice, which have two uterine horns ac-customed to multiple pregnancy, in con-trast to the single uterine segment ofhuman beings in which a single preg-nancy usually develops. Perhaps here wehave an example of the inapplicabilityof the results of animal experiments tothe results obtained in human beings.Third, the nature of the test was ex-plained carefully to each patient. after6 SEPTEMBER 1957

IN FABRICATINGi CUSTOM-MADE

Highl 'acuum Apparatusfor the Determination ofSurface Area by theBrnanler - Emmett - TellerMethod operating in theplant of C. K. Williams &Company, Easton, Penn-sylvania. The apparatus,for measuring gas adsorp-tion isotherms, is made of"P'yrex" brand glass. ItIvas designed in coopera-tiol) with the SurfaceChemistry Laboratory ofLehigh University.

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C a *~~~~~,, S7 211Fine, American-Made Instrument at Over 50% Saving

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output in response to an input signalcomposed of sine waves or pulses ofeither polarity and of frequency up to100 kcy/sec. The delay generator, in re-sponse to the trigger pulse, furnishes posi-tive and negative delayed pulses, positiveand negative gating pulses, and a linear,negative-going ramp function. Time in-terval is controlled in five full-scaleranges from 1 to 10,000 psec. ( BurroughsCorp., Dept. S568r uruh

* TRANSISTORIZED CONVERTER is designedfor input of 24 to 28 v d-c and input cur-rent of 2.3 amp. Output is 270 v d-c at150 ma. Voltage regulation between 15and 150 ma is better than 85 percent.Ripple is 0.03 perctent. Temperature riseis 100C at 150 ma. Weight is 3 lb. (Air-craft Radio Corp., Dept. S496)

*NAVIGATION INSTRUMENT iS Com-pletely transistorized for portability. Theentire equipment, including batteries,weighs 40 lb. The 20-lb battery case maybe dispensed with if a 24-v source ofdirect current is available. The instru-mnent measures distance with accuracyranging from 1/5000 to 1/50,000.(Hastings-Raydist, Inc., Dept. S530)

* HIGH-SPEED CENTRIFUGE for micro-hematocrit work features quiet opera-tion resulting from shock mounting andcareful balancings Interlock switchesprevent operation when the lid is notproperly secured. Interchangeable headsaccommodate 24 capillary tubes or 8capillary tubes and 8 serum tubes. (Clay-Adams, Inc., Dept. S535)

* PARAFFIN D)ISPE-NSER inelts and keepsparaffin at a controlled temperatureready for use. As it is needed, the par-affin may be drawn off through a self-closing faucet. The unit is portable andholds about 10 lb of paraffin. Tempera-ture is adjustable and is indicated by adial thermometer. (Barnstead Still andSterilizer Co., Dept. S538W

*THERMAL CONDUCTIVITY lTEST CON SOLEemploys the guarded-hot-plate principle.Hot surface temperatures are automati-cally maintained in the range 100° to14000F. Cold surfaces are automaticallycontrolled between 600 and 600'F. Co-efficients of thermal conductivity up to5.0 Btu/ft2 hr FO in. can be determined.The unit confornms-to ASTM specifica-tion C177-45. (Parameters, Inc., Dept.S569)

* LINEAR INTEGRATOR is a ball-and-diskintegrating mechanism assembled with acounter and an output-pulse switch. Itcan be adapted to strip-chart recordersof all types. Changes in the variable tobe integrated position a ball carriage sothat counter speed will be proportional

j to the integral of the variable with re-

mercuryvapordetectortells instantly when a hazard existsin plant or lab atmospheres

Meter is calibrated in mercury concen-trations for quick indication. The toxiclimit is a full-scale reading on the highsensitivity scale of Model 23, illus-trated. Wt.: 7 lbs.; size 13" x 81/" x41/2". Three models for varying ranges.

Write for bibliography on the mer-cury vapor hazard, and literature onKruger Mercury Vapor Meters.

HAROL RUGER

BOX 164 * SAN GABRIEL, CALIF.

I IINC.

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American ElectronicLaboratories, inc.121 N. 7th Street, Phila. 6, Pa.

SCIENCE. VOL. 126

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spect to time. The output pulse can beused to transmit the reading to a remotecounter or recorder. Input torque is lowenough to permit acceptance of the out-put of sensing elements directly. (Libra-scope, Inc., Dept. S575)

* COMPARATOR, for setting relay contactsto precise gap dimensions, is a projectionunit consisting of collimated light source,magnification system, and hooded screen.An adjustable base provides a dovetailslot for mounting. Magnifications from10 to 100 are available. (Stocker andYale Inc., Dept. S567)

* VOLTMETER has a phase-sensitive recti-fier. Both magnitude and phase of a sig-nal can be measured. The instrument isdesigned for 400 cy/sec phase measure-ments but may be adapted at the factoryto 60 cy/sec, 1000 cy/sec, or other fre-quencies. Its ranges as a voltmeter are1 mv to 300 v full scale from 10 cy/secto 50 kcy/sec. Phase angle is read on aCalibrated phase-shifter dial. (North At-lantic Industries, Inc., Dept. S571)

* ELECTROMETER covers a current rangefrom 10-3 to 10-11 amp. Accuracy is ± 1percent to 10-10 amp and ± 2 percent at10 -11 amp. The instrument employs apentode electrometer tube with a d-cfilament and a regulated voltage supply.Zero drift is 10 mv/day after '/2-hrwarm-up. (Tullamore Electronics Labo-ratory, Dept. S576)

* FOUR-MILLIMETER KLYSTRON is a wave-guide-output reflex type. It is tunableover a minimum of 6 kMcy/sec in therange from 65.5 to 77.5 kMcy/sec. Out-put is 40 mw at band center and 10 mwminimum across the band. Focusing iselectrostatic. Heater power requirementis 10 v, 0.4 amp. (Amperex ElectronicCorp., Dept. S578)

*BORESCOPE permits complete internalinspection of tanks, vessels, and othercavities by means of an adjustable mir-ror which can be controlled by a handwheel. Magnification is 10, and the fieldis 9 in. in diameter at a distance of 24 in.The viewing head incorporates a 13/16-in. diameter, 100-w lamp for illumina-tion. (Lenox Instrument Co., Dept.S579)

* RECORDING OSCILLOGRAPH uses eightdual-gun cathode-ray tubes to record upto 16 channels at frequencies up to 100kcy/sec. An optical system focuses traceson photographic film or paper 8 in. wide.Eight record speeds from 3 to 400 in./secare selectable without gea r pulleychanges. Continuous 400-ft records canbe run. (Consolidated ElectrodynamicsCorp., Dept. S590)

JOSHUA STERNNational Bureau of Standards

Meets the very highestrequirements for researchand scientific exploration,and provides unmatchedversatility in many fields ofmicroscopy.Features include sextuple revolvingnosepiece if desired a 20 Watt built-inillumination . beam splitting photo-tube for binocular focusing for photo-micrography * phase contrast plus acomplete line of attachments forevery observation method.

A highly precise instrument,ideal for the laboratory andmany research applications.Lightweight, easily portable and self-protected by the sturdy steel hood,the Wild M 11 offers a degree of ver-satility and precision far beyond itsprice and size. Outstanding optics,low-placed fine adjustment, easilyinterchangeable accessories andmany other features make this amost noteworthy instrument for hos.pitals, expeditions and educationalinstitutions. _ _

M 11 M 20

I_ In_==_s___R_:x33-_=

s ^.iS i mu. it u as ^ At a a, is

6 SEPTEMBER 1957. 467

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EQUIPMENT NEWSJOSHUA STERN

DOI: 10.1126/science.126.3271.465-b (3271), 465-467.126Science

ARTICLE TOOLS http://science.sciencemag.org/content/126/3271/465.3.citation

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trademark of AAAS. is a registeredScienceAdvancement of Science, 1200 New York Avenue NW, Washington, DC 20005. The title

(print ISSN 0036-8075; online ISSN 1095-9203) is published by the American Association for theScience

of Science. No claim to original U.S. Government Works.Copyright © 1957 The Authors, some rights reserved; exclusive licensee American Association for the Advancement

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