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Jan 1942

Volume 13, Issue 1, pp. 1-45


Physical Instruments for the Biologist

Detlev W. Bronk

Rev. Sci. Instrum. 13, 1 (1942); http://dx.doi.org/10.1063/1.1769926 (2 pages)

Online Publication Date: 27 December 2004

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Abstract Unavailable

A Method of Minimizing Supercooling and Its Application in the Determination of Freezing Points from Dielectric Constant Measurements

Thomas M. Shaw

Rev. Sci. Instrum. 13, 2 (1942); http://dx.doi.org/10.1063/1.1769929 (4 pages)

Online Publication Date: 27 December 2004

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The determination of the freezing points of water in colloidal systems from dielectric constant measurements is shown to be unsatisfactory when supercooling occurs. A method is described for minimizing supercooling, which makes possible accurate determinations of the freezing point. Data showing the freezing points obtained for a Barnes soil at various moisture contents are included.

Rotating Bubble Method for the Determination of Surface and Interfacial Tensions

Bernard Vonnegut

Rev. Sci. Instrum. 13, 6 (1942); http://dx.doi.org/10.1063/1.1769937 (4 pages) | Cited 28 times

Online Publication Date: 27 December 2004

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A new method for the measurement of surface and interfacial tensions is suggested. The two phases to be investigated are placed in a closed container which is rotated at a known speed about a horizontal axis. Under the influence of the forces of rotation and of surface tension the lighter phase will take the equilibrium shape of an elongated bubble along the axis of rotation. If the length of the bubble is made large compared to the radius, the shape of the bubble can be closely approximated by a circular cylinder with hemispherical ends. For the case of a long bubble expressions are derived for the surface tension as a function of the bubble dimensions and for the shape of the bubble end.

An All Electric Integrator for Solving Differential Equations

Robert N. Varney

Rev. Sci. Instrum. 13, 10 (1942); http://dx.doi.org/10.1063/1.1769927 (7 pages) | Cited 2 times

Online Publication Date: 27 December 2004

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Four basic devices are required for an integrator of differential equations. These are (1) integrating units themselves, (2) coupling devices for interlocking the various integrators and multipliers, (3) multiplier units, (4) generators of functional coefficients entering into differential equations. These devices and their applications to various types of problems are given. Results of an entirely completed machine are not available, but preliminary results show the device to be good to half a percent and potentially in some cases to nearly a tenth of a percent. The electric coupling used renders the machine very free from mechanical difficulties and also reduces the cost enormously. A machine capable of attacking many theoretical problems might cost as little as $5000.

An Electronic Voltage Stabilizer for 1 to 50 kv and 20 to 500 ma

L. G. Parratt and J. W. Trischka

Rev. Sci. Instrum. 13, 17 (1942); http://dx.doi.org/10.1063/1.1769928 (7 pages) | Cited 9 times

Online Publication Date: 27 December 2004

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A description is given of the design and performance of an electronic superdegenerative stabilizer in the output of a d.c. high voltage supply. This stabilizer is proposed as a satisfactory and economical solution, alternative with the usual controlled motor‐generator set, of the problem of obtaining very steady high voltage at rather large powers (1 to 50 kv and 20 to 500 ma in the present design). The device reduces the residual ripple from the filter as well as stabilizes against fluctuations in the input voltage. The stabilizer, containing an 833 type tube with two stages of amplification in the grid circuit, is essentially a modification of the degenerative type of stabilizer; but, taking advantage of grid current, the stabilizer may be adjusted to have positive, negative, or infinite stabilization ratio. The device, using grid current, warrants a new name, and is termed a superdegenerative stabilizer.

Two Bridge‐Controlled Thyratron Thermostats

Dennison Bancroft

Rev. Sci. Instrum. 13, 24 (1942); http://dx.doi.org/10.1063/1.1769930 (4 pages) | Cited 6 times

Online Publication Date: 27 December 2004

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See Also: Erratum

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Two circuits for the regulation of temperature by means of a bridge‐controlled thyratron are described. The first utilizes a resistance thermometer; the second controls through changes in the resistance of the furnace winding. Improved stability is achieved by adequate filtering of the voltage applied to the control grid of the thyratron. The circuits are so designed that extreme overload in control voltage never causes erratic behavior; thus when the thermostatic bridge is set for a new temperature, unstable operation does not occur, and control is established smoothly and promptly.
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Analyzer for One ml of Respiratory Gas

P. F. Scholander

Rev. Sci. Instrum. 13, 27 (1942); http://dx.doi.org/10.1063/1.1769931 (5 pages) | Cited 1 time

Online Publication Date: 27 December 2004

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Abstract Unavailable

Volumetric Microrespirometers

P. F. Scholander

Rev. Sci. Instrum. 13, 32 (1942); http://dx.doi.org/10.1063/1.1769932 (2 pages) | Cited 15 times

Online Publication Date: 27 December 2004

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Abstract Unavailable

The Electrical Capacitance Diaphragm Manometer

John C. Lilly

Rev. Sci. Instrum. 13, 34 (1942); http://dx.doi.org/10.1063/1.1769933 (4 pages) | Cited 9 times

Online Publication Date: 27 December 2004

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A new type of diaphragm manometer for direct pressure measurements in the arterial blood stream and in other fluid systems is described using a radiofrequency, crystal‐controlled oscillator and a pressure‐sensitive condenser in the pick‐up unit. The potential drop due to the plate current of the oscillator tube flowing through a resistor is amplified, and is observed and photographed by means of a cathode‐ray tube. Sensitivity control is obtained by the use of an inverse feed‐back network in the amplifier. The range of sensitivity is from a maximum of one mm Hg per inch of cathode‐ray tube spot deflection to any desired minimum. The approximate cut‐off frequency of the manometer is 580 c.p.s. when used with a number 20 needle, 475 c.p.s. with a number 22 needle and 205 c.p.s. with a number 26 needle, each one inch long. These values are higher than those of previous diaphragm manometers with the same size liquid system and the same size needle. Sample records of the arterial pressure are presented.
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A Simple Type of Flat Induction Coil

Elliot T. Benedikt

Rev. Sci. Instrum. 13, 38 (1942); http://dx.doi.org/10.1063/1.1769934 (1 page)

Online Publication Date: 27 December 2004

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See Also: Erratum

Abstract Unavailable
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New Instruments

Wm. F. Roeser

Rev. Sci. Instrum. 13, 38 (1942); http://dx.doi.org/10.1063/1.1769935 (4 pages)

Online Publication Date: 27 December 2004

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Abstract Unavailable
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New Materials

A. R. Olpin

Rev. Sci. Instrum. 13, 41 (1942); http://dx.doi.org/10.1063/1.1769936 (5 pages)

Online Publication Date: 27 December 2004

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Abstract Unavailable
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