bluuebunny/crossref_metadata_2025 huggingface dataset:
Three Superfluous Systems of Electromagnetic Units
Authors: Campbell George A.
Published: January 2005

At the present time the electromagnetic, electrostatic, Heaviside-Lorentz, practical and international systems of electric and magnetic units are used side by side in pure and applied electromagnetism. The question is here raised whether the use of this multiplicity of units should continue indefinitely into the future when the conversion tables for translating from any system to any other system show the essential equivalence of all five systems. It is recommended that but one system be legalized and used generally in place of the five systems, and that this universal system be the coherent meter-kilogram-second-ohm or definitive system. It is further recommended that the international ohm be used in this system. This unit is the one actually used in exploring the physical world because laboratory resistances for physics and test room resistances for engineering have been so calibrated. Of far greater importance is the fact that by retaining the international ohm it will be simpler, and completely feasible, to eliminate what Heaviside called ``that unmitigated nuisance, the 4π factor of the present B.A. units'' from our preferred system of units.
The Theory of the Interpretation of Seismic Travel-Time Curves in Horizontal Structures
Authors: Slichter L. B.
Published: January 2005

The theory of the interpretation of seismic travel-time curves for refracted rays in horizontal structures is treated after the manner of Herglotz-Wiechert, under the customary assumption that the ray paths obey the laws of geometrical optics. Multiple valued travel-time curves, discontinuous velocity functions, and the discontinuous travel-time curves associated with a slower speed bed receive special consideration. It appears that interpretations satisfactory from the theoretical point of view may be obtained in these cases, although, experimentally, sufficiently complete data to meet the requirements of theory may often be difficult or impossible to obtain.
The Measurement of the Phase Angles of Shielded Resistors
Authors: Berberich Leo J.
Published: January 2005

In this paper is discussed the problem of measurement of the small, but not always negligible, phase angles of resistors, with special reference to shielded resistors of 1000 ohms and above. Several types of shielded resistors are described briefly, among which is the ideally shielded, low-phase-angle resistor, recently constructed by the writer. The substitution method developed is one in which the resistor, the phase angle of which is desired, is compared, by means of bridge circuit, to a reference standard of a simple geometric configuration and of approximately the same resistance as that of the resistor. The results of measurements, at frequencies of 500 and 60 cycles, on three ideally shielded resistors are given. By a series connection of resistors it is possible to extend the range of the method to 50,000 ohms.
Capillary Action in Impregnated Paper Insulation
Authors: Whitehead J. B. , Greenfield E. W.
Published: January 2005

The capillary rise of oil in vertical strips of impregnated paper obeys the same law as the rise of liquids in capillary tubes of circular cross section. From the viscosity and surface tension of an oil and its rate of rise in a given paper, it is possible to compute the ``effective capillary radius'' of the capillary pores of the paper. The rate of rise in a calibrated paper affords a convenient means of measuring the surface tension when the viscosity of the liquid is known. The rate of penetration of an oil into a paper is directly proportional to the ``penetrativity'' of the oil as defined in the theory of capillary action. The penetrativities of nine insulating oils and the effective capillary radii of seven different papers have been determined. A uniform relationship between the effective capillary radius and the Gurley air resistance of the paper is indicated.
On the Piezoelectric Properties of Tourmaline
Authors: Fox Gerald W. , Underwood Morris
Published: January 2005

Oscillating piezoelectric plates of different frequencies have been made from California and South African Tourmaline. These plates have a frequency response of approximately 3770 kc per millimeter of thickness. The temperature coefficient for both specimens was found to be negative and is about 35.5 parts per million per degree centigrade for the African specimen and 38.1 parts per million per degree centigrade for the California crystal. Comparison of the tourmaline plates with a Y-cut quartz plate of the same size and frequency shows the tourmaline oscillators decidedly inferior on the basis of power output.
The Theory of Refraction Shooting
Authors: Muskat Morris
Published: January 2005

Considerations of geometrical optics indicate that the limiting rays travelling along the interface between two homogeneous elastic media should carry inappreciable amounts of energy. Nevertheless, the ``first arrival'' waves in refraction shooting processes, which give linear time distance curves, are usually interpreted as being due to such limiting rays travelling along the interface with the velocity of the lower medium. To clear up the situation an analysis of the problem has been made both from the points of view of geometrical optics and wave theory. It is pointed out that although the assumed ``refraction'' paths are minimal time paths in the sense of Fermat's principle the applicability of the latter along a surface of discontinuity may be open to question. On the other hand, it is proved that, geometrically, they are necessarily real, since they are the only type of path that can give the observed linear time distance curves. The wave theory treatment of the problem for fluid media modified slightly from the operator method analysis previously given by Jeffreys, is then presented to show that the wave theory actually gives waves whose geometrical interpretations are exactly those of the refraction shooting process. Their amplitudes vary inversely as the square of the distance from the source and they give vertical displacements of the same order as those of the directly reflected waves. The analysis is extended to the case of general elastic media and it is shown that four types of ``refracted'' waves will be produced upon the incidence at the interface of either a longitudinal or transverse wave pulse. Two of the waves will be recorded as longitudinal waves and the other two as transverse. One of each pair effectively travels in the second medium with the longitudinal velocity of the medium and the other two travel with the transverse velocity of the lower medium. The velocities and accelerations produced by these ``refracted'' waves will vary over the pulse thickness exactly as the displacements and velocities in the incident pulse.
The Diffusion of Thorium in Tungsten
Authors: Fonda Gorton R. , Young Andrew H. , Walker Amy
Published: January 2005

Thoriated tungsten wires have been so heat-treated in gas as to develop variations in grain size, ranging in length from 4 μ to 3 cm. These variations produced marked changes in the thermionic emissive characteristics, such as rates of deactivation and of activation and duration of emissive life at normal operating temperature. The heat of diffusion remained unaffected. It was concluded that intergranular diffusion of thorium through tungsten is relatively too rapid to be measured and that the observed phenomenon depends purely on intragranular diffusion. This conception is in accord with the existence of a critical grain size for the realization of a maximum emissive life. Experiments are also described to demonstrate the spreading of thorium atoms over the surface of a single crystal of tungsten and to manifest the effect of slight strains in the lattice upon activation.
A Study of the Electrical Breakdown of Liquids by Means of the Electro-Optical Shutter
Authors: Washburn Harold W.
Published: January 2005

The static and the impulse breakdown of paraffin oil and xylol were investigated by means of the electro-optical shutter. To obtain satisfactory operation of the shutter it was found necessary to use a double shutter consisting of three crossed nicol prisms and two Kerr cells. Because of the liquids being only commercially pure and of the occluded air and moisture, several types of sparks were observed for a given method of applying the voltage. For the early stages of static breakdown, however, the ionization was usually more intense at the anode. With impulse breakdown in paraffin oil there was observed no increase in uniformity of type of breakdown as compared to static breakdown. With xylol, on the other hand, a fair degree of uniformity in type was observed. This uniformity was due to the extremely short time of voltage application, thus causing a decrease in the secondary effects resulting from impurities and occluded gasses.
The Measurement of Heat Production in Diathermy
Authors: Hemingway Allan , McClendon J. F.
Published: January 2005

Resistance and reactance of diathermy patients to alternating currents of varying frequencies up to and including radiofrequencies have been measured with a high frequency Wheatstone bridge. At frequencies greater than one million cycles per second the resistance becomes constant and the reactance and phase angle decrease to zero. Under these conditions the human body behaves as a pure resistance and the heat production in calories can be computed from the formula 0.24 VIt where V is the root-mean-square voltage, I the root-mean-square current and t the duration time in seconds of the diathermy treatment. High frequency resistances of various parts of the body which are usually treated with diathermy are given.
The Effect of Inductance on the Intermittent Glow Discharge
Authors: Kock Winston E.
Published: January 2005

The insertion of an inductance in the condenser arm of an intermittent glow discharge circuit was found to affect the characteristics of the oscillations. The voltage-frequency curve was noticeably altered, the wave form of the voltage across the condenser became sinusoidal and other new wave forms were introduced. Within a certain range, the frequency of oscillation was practically independent of the voltage, resistance or tube characteristics. Various applications are suggested.
Ball Lightning
Authors: Jensen J. C.
Published: January 2005

The size, appearance and physical properties of ball lightning has been subject to much controversy and but few accurate data are available. Description is given of a series of five photographs showing luminous masses which were of unusual size and which remained visible in changing form for about 3 minutes. Suggestions for further investigations are given.
Velocity of Elastic Waves in Granite and Norite
Authors: Leet L. Don
Published: January 2005

The velocities of elastic waves were investigated in granite at Rockport, Massachusetts, and norite at Sudbury, Ontario. The waves measured were generated by dynamite explosions, and recorded by portable seismographs at distances up to 6260 feet in granite and 10,320 feet in norite. The observed velocities in km/sec. with probable errors indicated by ± were: LongitudinalTransverseRayleighRockport granite5.14±0.0052.70±0.02  2.19±0.007Sudbury norite6.22±0.003  3.49±0.0062.79±0.01From these velocities, and the densities of specimens taken from the shooting locations, the following elastic constants may be computed. They are shown below, for comparison, with those computed by a similar procedure in an earlier report for Quincy, Massachusetts, granite. A quartz-rich zone in the norite was found to transmit the waves with a slower speed. The results are compared with statical measurements of Zisman on rocks from the same locations, a part of the same program of geophysical research at Harvard. Compressibility, measured directly, under hydrostatic pressures, on specimens exposed to the liquid transmitting the pressure is found to be the only statically determined constant which yields seismically effective values. The geological significance of granite velocities and elastic constants is discussed. It is concluded that a longitudinal-wave speed of 5.5 km/sec. cannot be regarded as unique for granite, or even necessarily suggestive of granite, as has been repeatedly proposed; and that there is as yet no seismological justification for the identification of any ``layer'' of the earth's crust as either sedimentary or granitic.
The Fluidity Method for the Determination of Association. II
Authors: Bingham Eugene C. , Spooner Laurence W.
Published: January 2005

This part contains fluidity data for about 346 liquids to be used for reference. They are arranged as fluidities at particular temperatures. Temperatures at particular fluidities were also obtained and from the latter tables, associations were calculated. The factors affecting association are briefly discussed which leads us to a tentative classification of associating and protecting groups. Finally the distinction between association, polymerization and condensation and polymerization is discussed.
Anomalies in the Viscosity of Mineral Oils at Low Temperatures
Authors: Louis  , Jordachescu  , Thiebault
Published: January 2005

Viscosity measurements at low temperatures show that after a temperature change an oil may require several weeks to attain an equilibrium state. Oils which show this viscosity anomaly are not truly viscous. The existence of a starting pressure called the yield value was not confirmed by experiment since the oil flows even under very slight pressure.
An Inverse Boundary Value Problem in Electrodynamics
Authors: Slichter L. B.
Published: January 2005

From knowledge of the electromagnetic field at the surface of a half-space due to a prescribed oscillatory source, is determined the unknown variation with depth of the conductivity and the dielectric constant. Unique solutions exist for these quantities.
Infrared Absorption Spectra of Certain Organic Compounds, Including the Principal Types Present in Gasoline
Authors: Kettering Charles F. , Sleator W. W.
Published: January 2005

The absorption spectra for twenty-five compounds, of which seventeen are typical of the important components of gasoline and which include both chain and ring molecules, all in the vapor state, have been examined throughout the spectral range 1μ to 30μ, by using prisms of NaCl, KCl and KBr. The percentage absorption is shown graphically in the charts which follow as function of the wave-length for specified amounts of material. The curves indicate certain distinctive features characteristic of each different molecule, as well as bands common to several or all the compounds. The resolution was not sufficient to separate rotational lines in any of the bands. In addition to the hydrocarbons, eight other substances, tetraethyl lead (the only material studied in the liquid state), tetraethyl germanium, tetramethyl tin, and tetramethyl lead and also aniline, dicyclopentadiene, methyl nitrate and diethyl peroxide were investigated. They were included in the list on account of their influence upon the detonation of fuel in the gasoline engine.
Stress Distribution in Wedges with Arbitrary Boundary Forces
Authors: Brahtz J. H. A.
Published: January 2005

Stress distribution under plain strain in a corner of any angular magnitude. A generalization of the method of von Kármán, applicable to the wedge, for any force distribution over the straight boundaries is outlined. In the first application the stress function is found for a concentrated force acting at any point of the boundaries of the three-quarter plane. Certain stresses are plotted. The stress functions are given without mathematical details for the following boundary conditions in the three-quarter plane: (a) Uniform tension over a part of the boundary; (b) linear distribution over a part of the boundary; (c) superposition of (a) and (b), giving hydrostatic distribution, with a plot of certain stresses. The discussion contains the stress functions for uniform continuous tension on one or both boundaries and points out the very interesting paradox that stresses may be finite for certain continuous loadings, but become infinite if a portion of the load is removed.
Characteristics and Functions of Thyratrons
Authors: Hull A. W.
Published: January 2005

The Thyratron is a tube of very low resistance (arc discharge) which can be started or prevented from starting by a grid. Its qualities are: enormous power-amplification, approximately 1011 per tube; efficiency between 95 and 99 percent at all voltages above 250; unlimited size, as regards current-capacity; high-voltage limit equal to that of the Pliotron; starting time one to six microseconds; deionization time 10 to 500 microseconds.

Use of Thyratron as switch and for power control. The controlling element may be a switch, clock, thermostat, or photo-tube; the controlled element a motor, magnet, contactor, or reactor. Typical applications of this kind of use are; turning on lamps at dusk, dispatching products to predetermined stations, cutting hot steel bars to exact length, opening doors at the approach of a person, wrapping packages, sorting beans and other articles, counting people or products, operating line or spot welding machines. By varying the phase of the grid-voltage with respect to that of the anode voltage, a smooth variation of average anode current may be obtained. A typical application is the dimming and blending of lights in theaters.

Use of Thyratron as rectifier and as inverter from direct to alternating current. Immediate objectives are frequency changing, from 60 to 25 cycles for railway and power purposes, and from 60 to 200 for spinning mills; and commutatorless motors of variable and controllable speed. A more remote but important application is d.c. transmission of power, with inversion to a.c. at the point of utilization.

Use of Thyratrons in scientific research. Applications include high-speed stroboscopes, timing devices, synchronous switches, and voltage regulators. Most interesting and promising of all is a device for counting alpha-particles, protons, and neutrons.
Mutual Impedance of Long Grounded Wires When the Conductivity of the Earth Varies Exponentially with Depth
Authors: Gray Marion C.
Published: January 2005

This paper presents a formula for the mutual impedance of long grounded wires above the surface of the earth, on the assumption that the conductivity of the earth varies exponentially with depth according to the formula γ=γ0e−bz. For b=0 the formula reduces to the known result for a uniformly conducting earth, while if b is allowed to become negatively infinite it reduces to the result for an earth consisting of a conducting layer at the surface only. For small values of b the first terms in the expansion of the impedance formula in powers of b are obtained, and curves are included of the real and imaginary parts of the coefficient of b.
On the Nature of ``Yield-Value''
Authors: Blair G. W. Scott
Published: January 2005

The problem of the flow of materials at stresses far below their normal yield-values is discussed, and it is pointed out that the sharpness with which yield-values can be measured depends on the grouping of the relaxation times for the different strains set up within the material, an uneven distribution making for a sharper definition. Any sharp and drastic change in the relaxation time of the system as a whole may justifiably be said to constitute a yield-value, the question as to which of these points is actually taken as the yield-value depending on the conditions of the experiment. These considerations are reinforced by a discussion of the results (to date) of certain experiments on flour doughs, and it is claimed that flour dough is a peculiarly suitable material for such investigations. A new rapid method for studying flow in flour doughs, recently described in the literature, is discussed. The dangers of classifying materials in hard-and-fast rheological divisions is emphasized, while it is pointed out that for practical purposes, and given adequate safeguards, such classifications may be extremely useful.
The Rheological Properties of Cement and Cement-Mortar-Stone
Authors: Bingham Eugene C. , Reiner Markus
Published: January 2005

Beams of cement-stone and cement-mortar-stone with the ratio of cement to sand of 1 : 3 were allowed to bend under their own weight, the cross section of the beams being 2.27 cm square and the distance between the supports 76.1 cm. The deflections were determined at the central point between the supports by means of an Ames gauge reading to 1μ; the experiments were extended over a period of seven months. The curve of the deflection vs. time generally starts as a parabola having a vertical tangent but beyond a certain point the curve becomes linear. The slope of the curve is a measure of the mobility of the material. The parabolic curve is due largely to the hardening of chemical origin, resulting from the absorption of water, which causes a gradual decrease in the mobility, but to a smaller extent to an elastic after-effect. The mobility of the cement is much greater than that of the mortar and it decreases with the degree of curing. The yield value of the mortar is smaller than 45×105 dynes/cm2 (65 lbs./in.2) and the yield value of the cement was not perceptible with the apparatus used. For all practical purposes, cement-mortar-stone may be regarded as a solid of very low rigidity and cement-stone as a very viscous liquid. The curvature of the stress-strain curve, usually observed, is due to elastic after-effects arising from the fact that the experiments require time. The modulus of elasticity is smaller in the case of cement (230–260,000 kg/cm2) than in the case of mortar (270–300,000 kg/cm2); it increases with the number of curing days and approaches a constant value.
Magnetic Properties of the Iron-Nickel Alloys Under Hydrostatic Pressure
Authors: Steinberger R. L.
Published: January 2005

A series of well annealed iron-nickel alloys in nominal steps of 10 percent Ni, including pure iron and pure nickel, has been examined for the effect of pressures, up to 12,500 kg/cm2, on the magnetic flux density. The application of pressure to a well annealed specimen causes a relatively large change in flux, usually a decrease and an incomplete recovery on release of pressure. The recovery is reversible in the sense that the same curve of flux change is traced with each series of pressure applications, provided the measuring pressure does not exceed that first applied. The 30 percent Ni alloy is rendered nearly nonmagnetic by a pressure of 12,000 kg/cm2. In the remaining metals pure iron exhibits the greatest and 90 percent Ni the smallest pressure change of flux. At constant field the different alloys exhibit various types of pressure changes of flux; linear, nonlinear and types exhibiting hysteresis.
Direct Measurement of the Gravitational Effect of the Moon
Authors: Hartley Kenneth
Published: January 2005

The sensitivity of the gravity balance described in the March, 1932, number of Physics is such that a correction must be made for the effect of the attraction of the moon. This lunar effect has been measured by hourly readings over one complete cycle and agrees, within the observational error, with the effect calculated for the vertical component of the pull of the moon without any compensation for the centrifugal effect of the earth's motion around the center of gravity of the system. The effect has a period of 24.8 hours and not 12.4 hours as the tides, there is no trace of the twelve-hour period. Values of gravity plotted against time follow accurately a sine curve which shows a small time lag as compared with the theoretical curve. This does not seem to be accidental but has not been explained.
The Gliding of a Snake
Authors: Jones Arthur Taber
Published: January 2005

The snake is replaced by a model consisting of a number of spools separated by light pins and held together by rubber bands. The forces that act on one spool are considered. If the spool is in equilibrium between curved guides, and if the tensions in the rubber bands are altered in such a way that there is no change in the resultant longitudinal forces, but that the curvature of the given part of the model tends to increase, it is shown that there is a tendency to slip along the guides toward a region where the curvature is greater.
Operating Constants for Direct-Current Thermionic Amplifiers
Authors: Macdonald P. A. , Tweed T. W.
Published: January 2005

The sensitivity to voltage, measured in volts per mm scale deflection, of a direct-current thermionic amplifier (simple circuit) is taken as inversely proportional to the mutual conductance divided by the plate current of the valve employed. The mutual conductance is found to decrease less rapidly than the plate current, as the filament and plate potentials are lowered. The most sensitive operating value of the plate potential of a UX 222 is found to be 1.5 volts giving a voltage sensitivity of 8×10−4 volt/mm in the simple circuit with no plate current compensation. By suitable use of the screen grid, a grid-filament resistance of 1014 ohms may be obtained giving a current sensitivity of 8×10−15 amp./mm with an input resistor of 1011 ohms.
Minimum Capillary Rise in an Ideal Uniform Soil
Authors: Smith W. O.
Published: January 2005

The rise, into an ideal uniform soil, of liquid, under the action of capillary forces, differs from the steady flow across the soil. The steady transmission of fluids takes place through the continuous capillaries extending across the soil; the rise, under capillary forces, of liquid is from cell to cell. The hexagonal scheme of grains spaced at a distance (2r+d), where d is a function of porosity, is used as a statistical representation of the soil; and the problem discussed from the standpoint of this packing. The fluid, in its passage through the long capillaries, flows through a cyclic capillary showing definite maxima and minima in each element; and likewise, the rise, from cell to cell, under capillary forces, is through a channel with definite maxima and minima. The minimum opening, of a cell, is the section defined by the plane of centers; the greatest is the section defined by the plane, parallel to the plane of centers, tangent to the grains of the cell immediately over the first cell. The greatest rise, occurs when the minimum opening holds the meniscus and is observed by allowing the liquid to fall through the soil; the least rise should occur when the maximum opening holds the meniscus and should be observed by allowing the liquid to rise through the soil. Wetting phenomena introduce, however, complications affecting the minimum rise. Rings of liquid form, just above the meniscus, around the point of contact of each pair of grains, and carry the rising liquid higher until it attains a position where it is no longer able to reach the rings so formed; equilibrium then prevails at a rise intermediate to the two extremes just defined. The exact conditions controlling the rise phenomena are determined; the approximation, developed for the capillary equation, in an earlier paper, is then used, with these conditions, to calculate the minimum rise. The results are compared with the data given in the earlier paper; good agreement, within the experimental error, is obtained.
Ionization in the Upper Atmosphere at About 200 km Above Sea Level
Authors: Hulburt E. O.
Published: January 2005

From the skip distances of radio waves measured in temperate latitudes during 1927 and 1928 the average day ionization is calculated to be at about 200 km above sea level with a maximum electron density of 7.5×105 and 5.6×105 for a summer and winter day, respectively, which agree with the observed virtual heights from radio echo experiments and the longest wave which at normal incidence pierces through the ionized layer. The ratio 1.33 of summer to winter day electron density agrees with the ratio 1.42 calculated from ionization by the ultraviolet light of the sun. An average night ionization of 2.5×105 and 1×105 for summer and winter at 160 km is in rough accord with the radio facts as far as they are known, but within limits a more dense ionization at a higher level, or a less dense at a lower level, would accord equally well. The average day ionization for 1927 and 1928 is 6.5×105 electrons cm−3 which, when compared with the value 4.3×105 calculated from the skip distances of 1923 and 1924, shows that the ionization increased by about 50 percent from minimum to maximum solar activity.
A New Correction in Viscometry by the Capillary-Tube Method
Authors: Bingham Eugene C. , Geddes John A.
Published: January 2005

The hydrostatic head correction as ordinarily made in viscosity measurements may be in error. This is made evident when one determines this correction at widely different pressures or with liquids of widely differing fluidities. It is concluded that this error is due to differences in the value of the coefficient m of the kinetic energy correction in different directions of flow. Such differences are due to departure of the capillary tube from a true cylinder which may have arisen in the manufacture of the capillary or of the viscometer. These differences in the value of m are so considerable that not only should the value of m for each viscometer be determined but a separate value should be determined for each direction of the flow through the capillary. Fortunately, this measurement is simple.
The Fluidities and Associations of Alcohols and Esters of High Molecular Weight
Authors: Bingham Eugene C. , Stephens Robert A.
Published: January 2005

The specific volumes and fluidities of six isomeric hexadecyl alcohols and the corresponding hexadecyl acetates have been measured from 0 to 100°C where practicable. The associations of these liquids have been calculated and shown to be extraordinarily low. This suggests the importance of further studies on the association of compounds of high molecular weight and low association.
The Viscosity of Barium Chloride in Aqueous Solution
Authors: Hood G. Raymond , Hohlfelder Leonard P.
Published: January 2005

Measurements are made on the viscosity of aqueous solutions of barium chloride at 18°C over the range 0.006 to 0.492 molality. The value of the constant A in the equation η=ηc/η0=1+Ac½ is determined and found to agree, within 4 percent, with the theoretical value of the constant as determined by Falkenhagen and Vernon. The constants of several empirical equations are also given.
The Viscosity of Urea in Aqueous Solution
Authors: Hood G. Raymond
Published: January 2005

While examining the literature relating to the viscosity of aqueous solutions, the writer noticed some measurements obtained in connection with the viscosity of aqueous urea which appeared to warrant a reinvestigation of this substance. The relative viscosity of aqueous urea was accordingly measured at 18°C and 25°C over a range of concentration from 0.005 to 1.876 mol/liter. Fluidity— volume-concentration curves exhibit negative curvature, evidencing that urea behaves like an electrolyte in that it decreases the fluidity of water less than would be expected on the basis of additive fluidities. It behaves like a non-electrolyte in that it exhibits no stiffening effect; i.e., the value of the Falkenhagen constant A is zero. A table is included, giving a comparison of the observed and calculated values of the Falkenhagen constant A for 11 electrolytes.
The Automatic Timing of the Ostwald Viscometer by Means of a Photoelectric Cell
Authors: Jones Grinnell , Talley S. K.
Published: January 2005

A new method for the automatic measurement of the time of flow of a liquid in a viscometer of the Ostwald type by means of a photoelectric cell is described. The elimination of the psychological errors inherent in the older technique permits greater precision. Other sources of error in the use of the Ostwald viscometer are analyzed and the precautions necessary for precision viscometry are discussed.
A High Voltage Sensitivity Direct-Current Amplifier
Authors: Macdonald P. A. , Campbell E. M.
Published: January 2005

It is shown that a negative resistance of a definite value, introduced into the plate circuit of a thermionic valve theoretically allows the voltage sensitivity to become infinite. Practical application is made to construct high sensitivity direct-current amplifiers. The data show a mutual conductance of 30,000 microamp. per volt.
Effect of Circuit Parameters on the Constancy of the Frequency of a Pliodynatron
Authors: Sears William C.
Published: January 2005

A study is made to determine the way in which the frequency of the pliodynatron oscillator depends upon the plate and control-grid voltages. The optimum operating voltages for greatest constancy of frequency are discussed. A new theoretical expression for the frequency of this oscillator is derived. The theoretical frequency variation with plate voltage is shown to be closely in agreement with the experimental variation.
A Photoelectric Valve
Authors: Kunz Jakob , Tykociner J. T.
Published: January 2005

The object of this experimental investigation was to determine the nature of the valve effect. After the description of the valve some characteristic and photometric curves are given. Sensitivity curves are then described which show the relation between the wave-length and the photoelectric current per unit of light energy. These curves show distinct maxima, like ordinary photoelectric cells; this character of the sensitivity curves support the theory that the effect is primarily a photoelectric phenomenon connected with space charges. Other assumptions are shown to be untenable. Some additional phenomena, expecially of the dark current, and experiments with various modifications of the valve are reported.
Viscous Resistance in Capillaries of Non-Uniform Radius
Authors: McLean D. A.
Published: January 2005

The viscous resistance offered by a tube of varying radius to the flow of a liquid is discussed. Three cases are taken up, for which solutions assume the forms:

(1) capillary tube viscometer: η=πP/8QAL.

(2) Bingham and Murray plastometer: η=P(t−t1)/8[f3(l)−f3(l1)].

(3) apparatus for studies of wetting under dynamic conditions: γ=4ηf5(l)/t.The functions AL, f3(l), and f5(l), may be obtained from a calibration of the tube, use being made of graphical integration.
Luminous Discharge Between Lecher Wires in a Partially Evacuated Tube
Authors: Hershberger W. D. , Zahl H. A. , Golay M. J. E.
Published: January 2005

In experiments with a Gill-Morrell oscillator generating undamped waves less than a meter in length, a study was made of the potential difference between the Lecher wires coupled to the oscillator by enclosing these wires in an evacuated glass tube several wave-lengths long. The oscillator itself employed two type −52 tubes connected in push-pull and it set up radiofrequency currents of 2.5 amperes in the Lecher wires and potential differences in excess of several hundred volts between the wires at positions separated by half wave-length intervals. At these voltage loops for certain critical pressures, between the wires a discharge took place which was photographed as well as employed in a direct study of the standing waves in the wires. The gases used in the tube were air, helium, oxygen, mercury vapor and mixtures of these gases with air. The use of this tube made possible a visual study of the changes in potential distribution as various circuit adjustments were made. A series of double maxima was observed as the length of the line was changed by a half wave-length.
The Interpretation of the Resistivity Prospecting Method for Horizontal Structures
Authors: Slichter L. B.
Published: January 2005

The direct problem of deducing from electrical potentials observed at the surface of a horizontally uniform earth the unknown variation of the conductivity with depth reduces to a boundary value problem of unusual type. Its solution for the isotropic case is developed in Part I, following. In Part II the more usual inverse problem is solved for some special classes of conductivity functions and graphical examples are given as an aid in guiding the interpretation work. In Part III, the anisotropic case is discussed.
The Theory of the Psychrometer. II. The Effect of Velocity
Authors: Arnold J. Howard
Published: January 2005

The psychrometric constant ψ, defined as the ratio of A (corrected for radiation) to the A predicted by the convection theory, is shown to be a function of velocity. At infinite velocity, the new equation reduces to that of August (ψ=1); at zero velocity, to the result obtained by Maxwell, ψ=K/D. An improved method of obtaining the true wet-bulb temperature is given, together with values of ψ, accurate to about 1 percent, for toluene, chlorbenzene and xylene. Straight lines are obtained when ψ for the latter two liquids against ψ for toluene at the same velocity. The theoretical psychrometric line for water is found; it is shown from theory that the line uncorrected for radiation possesses a stationary minimum value at velocities between 1000 and 10,000 ft./min., the radiation error just balancing the deviation from the August theory. In this range A is constant at 630×10−6, while at lower velocities it varies rapidly because of the change in the radiation error. For accurately reproducible results, the air velocity must be maintained at 1000 ft./min. or more.
The Shot Effect and Electrical Breakdown in Insulators
Authors: Haworth F. E. , Bozorth R. M.
Published: January 2005

Measurements are made of the fluctuations in currents passing through insulating materials subjected to high, constant electric fields. Applying the theory of the shot effect to these fluctuations we are able to calculate the average number of elementary charges (electrons or ions) which discharge onto the electrodes as a unit. In glass, this number increases exponentially with the field from about one at low fields to about 106 at fields just below breakdown. Considered with respect to various theories offered in explanation of electrical breakdown, our results indicate that the shot effect is caused by ``avalanches'' of electrons discharging through paths in the material over which breakdown occurs at higher fields, the avalanches increasing in size with the field until the material is ruptured. By making use of the Johnson effect (thermal agitation of electricity) a new and simple method has been worked out for calibrating the amplifier for shot effect measurements.
Unsteady Flow of Fluids in Oil Reservoirs
Authors: Hurst William
Published: January 2005

This paper is an analysis of the unsteady flow of a compressible fluid flowing radially to a well in a sand formation. The phenomenon of unsteady flow occurs as a result of fluid expansion. When the pressure in the formation is lowered, the fluids therein expand and the increase in volume imparts motion to the fluid which flows towards the region of lowest pressure in the formation. This process is continuous in the reservoir and extends further away from the well with increased production. By the ``equation of continuity,'' the solution for two specific cases of unsteady flow are derived. The first of these is that in which the fluid from a sand reservoir of limited size flows to a well in which the pressure at the level of the producing sand always remains constant. The variation of the pressure gradient, the rate of production, and the cumulative production with respect to time are given in Eqs. (11), (24), (29) and (30). The second case is that in which the flow of fluid to a well is such that the rate of production at the well is always constant. This case is derived by the assumption that the cylindrical body of sand, which is influenced by the well, is subject to a steady depletion of fluid, and in order that the rate remain constant at the well, fluid must flow into the reservoir from some extraneous source in increasing amounts. Eventually, however, the rate of flow of fluid into the reservoir becomes equal to the rate at which fluid is withdrawn from the well and steady flow is established in the sand. The equations for the pressure gradient and the decline of pressure at the well with respect to time are (39), (52) and (56).
A Magneto-Optic Method of Determining the Vitamin Content of Various Substances
Authors: Wissink G. M.
Published: January 2005

In this investigation, the magneto-optic apparatus was used, but it was modified to some extent from the original apparatus used by Allison. The modifications included a mercury vapor arc and a monochromator to furnish a steady source of monochromatic light, and a photoelectric cell and amplifier circuit to read the minima. The apparatus gave a distinct minimum, at 32.9 on the electrical path scale, for all substances tested which contained vitamin A but did not show this minimum for similar substances in which this vitamin was lacking. Pure carotene did not give this minimum. Pure carotene after irradiation with ultraviolet light, however, did give it.
Mutual Impedance of Grounded Wires Lying on the Surface of the Earth when the Conductivity Varies Exponentially with Depth
Authors: Gray Marion C.
Published: January 2005

This paper presents a formula for the mutual impedance of any insulated wires of negligible diameter lying on the surface of the earth and grounded at their end-points, on the assumption that the conductivity of the earth varies exponentially with depth. Various special cases are briefly discussed.
A Thermoelectric Metal-Crystal Analyzer
Authors: Hasler M. F.
Published: January 2005

A device is described which allows the measurement of the thermoelectric e.m.f. at room temperature for each increment of length of a metal test bar. A photographic arrangement permits a complete thermoelectric record of such a bar to be produced.
Thermal Agitation Voltages in Resistors
Authors: Neitzert C.
Published: January 2005

The limited range of previous measurements of thermal agitation voltage is pointed out and data are given which extend the range of resistances and frequencies considerably. The results substantiate Nyquist's theory for resistances up to 1.7×109 ohms and for frequencies between 1 and 10,000 cycles per second. A value of 1.366×10−16 ergs per degree with a probable error of 0.016×10−16 ergs per degree is obtained for Boltzmann's constant. This is nearer to the accepted value than previous determinations by this method have given.
An Inverse Boundary Value Problem in Seismology
Authors: Pekeris Chaim L.
Published: January 2005

It is shown that the variation with depth of the density and elastic constants of a half-space can be determined from the observed motion of the surface caused by a given distribution of stresses on the surface.
Study of Emergence Angle and Propagation Paths of Seismic Waves
Authors: Ewing Maurice , Crary A. P.
Published: January 2005

Travel-time curves are given for elastic waves through the earth in a region in which the velocity increases continuously with depth. These time-distance curves have been approximated by an equation of the form X=aT2+bT from which the velocity depth relation has been deduced. A new method for measurement of the emergence angle has been used and the values obtained agree reasonably well with those deduced from theoretical treatment of the time-distance curve. Formulas for the travel-time between any two points in the medium under consideration are derived. These formulas agree closely with two sets of direct measurements. In one of these the seismograph was placed at various distances directly beneath the explosion. In the second case it was placed at a fixed depth beneath the surface and the explosion was located on the surface at various distances. The approximate depth to bed rock is obtained from the time-distance curves by use of the formulas mentioned above.
The Electrical Conductivity of Glass Part I. The Formation of Highly Resistant Layers
Authors: Kiehl H. R.
Published: January 2005

An effort is made to distinguish more clearly between two types of phenomena which may occur in some glasses: (1) a ``reversible absorption'' current due to the formation of a high counter electromotive force, and (2) an ``irreversible absorption'' current due to the formation of a highly resistant layer in the glass. Characteristic curves showing one type of the latter which may occur under certain conditions are given. Although many observers seem to have observed both phenomena previously, considerable confusion still seems to exist in distinguishing between them. Combinations of both phenomena may be one possible cause of some of the large discrepancies in current-time behaviors reported. A study of the relatively small, slowly decreasing residual electromotive force observed upon discharging the sample shows a linear increase of this electromotive force with increase in temperature for temperatures as high as 150°C.
The Mechanism of Division of Small Liquid Systems Which Are the Seats of Physico-Chemical Reactions
Authors: Rashevsky N.
Published: January 2005

In continuation of a previous investigation, the mechanism of division of small liquid droplets, which are the seats of physico-chemical reactions, is being studied now not from thermodynamical, but from the kinetic point of view. Thermodynamical considerations give us conditions under which the whole drop is less stable, than its two halves. It does not say however anything about the degree of stability. The present investigation makes this next step, and shows under what conditions a drop becomes so unstable, that an infinitesimal deformation will lead to a division. The critical sizes calculated here are close to those calculated by thermodynamical method. The importance of ``release phenomena'' and ``valve action'' in the cases considered is pointed out.
Stabilizing Arcs by Electrode Surfacing
Authors: Suits C. G.
Published: January 2005

The effect of electrode surfacing on arc stability is studied for arcs between copper and silver electrodes in air at atmospheric pressure. For the copper arc it is shown that the random fluctuations in arc voltage and light intensity may be reduced to a very small value by giving the anode surface a high polish. Observations of the spectrum and volt-ampere characteristic are described. For the silver arc partial stability of arc voltage and light is obtained by electrode polishing.
Glass-to-Metal Seals
Authors: Hull Albert W. , Burger E. E.
Published: January 2005

The problems of sealing are adhesion and strain. The simplest, but perhaps not the only means of adhesion is a firm layer of metal oxide. Strains can be avoided if, and only if the thermal expansions of metal and glass are the same. This postulate is thoroughly tested. Equations are derived for the stresses in cylindrical seals, in terms of the difference in expansion of metal and glass, and the stresses thus calculated are compared with those observed photoelastically in carefully annealed test seals. Such tests are carried out on all the important sealing materials. These tests include accurate contraction coefficient measurements of glass and metals, (Fig. 8); graphical exhibition of axial stresses by photographs through crossed Nicols and a quartz wedge, (Figs. 9 and 10); and numerical evaluation of all the stresses, both theoretical and experimental, (Table VII). Two new sealing alloys are described: fernichrome (Fe 37 percent, Ni 30 percent, Co 25 percent, Cr 8 percent) which matches standard lead glass; and fernico (Fe 54 percent, Ni 28 percent, Co 18 percent) which matches Corning glasses G-71 and G-705 A O. The unique feature of these alloys is that their expansion characteristics are curved in such a manner that they match those of the glasses mentioned with considerable fidelity. The seals made with these combinations are found to be practically free from strain.
Analysis of Thermal Stresses in Sealed Cylinders and the Effect of Viscous Flow During Anneal
Authors: Poritsky Hillel
Published: January 2005

Equations are derived for the thermal stresses in long sealed cylinders due to different coefficients of expansion, on the basis that the material of the cylinder is elastic. The optical retardation due to this stress distribution is computed for a ray traveling normal to the axis, and is found to depend upon the axial stress only. The modification in the stress distribution is then investigated for the case when plastic or viscous flow takes place during annealing.