bluuebunny/crossref_metadata_2025 huggingface dataset:
A Vacuum Apparatus for Measuring Thermal Expansion at Elevated Temperatures, with Measurements on Platinum, Gold, Magnesium and Zinc
Authors: Austin J. B.
Published: January 2005

An apparatus for measuring linear thermal expansion between room temperature and 950°C in vacuo by an interference method has been developed and tested on platinum, gold, magnesium and single-crystal zinc. Although designed primarily for metals which oxidize readily it seems to give excellent results for all metals in the temperature ranges through which their vapor pressure is low. Under conditions such that a metal has a high vapor pressure the performance is not quite so satisfactory because of the deposition of metallic films on some of the cooler parts of the optical train. The refractive index of fused silica for the helium line λ=5877.2 has been calculated for the temperature range 18° to 950°C. A study of the dilatation of single-crystal zinc yields no evidence for the existence of more than one form between 20° and 350°C.
Note on Dipole Radiation Theory
Authors: Wise W. Howard
Published: January 2005

By fitting certain general asymptotic series solutions of the wave equation to known expressions for wave function components at the surface of the ground and on the upper infinite hemisphere, recurrence relations between the successive terms of the asymptotic series for some of the dipole wave function components are obtained.
The Temperature Distribution of a Gas Flowing Through a Furnace
Authors: Herzfeld K. F.
Published: January 2005

In recent experiments the heat of chemical activation (formation of radicals) has been determined by measuring temperature coefficients of reaction rates of gases flowing through a furnace. To justify this procedure, an investigation is necessary to find out to what extent temperature equilibrium is reached. In this paper it is shown that the flow is laminar, and that two cases must be distinguished. Temperature equilibrium is reached throughout the flow when the pressure drop is less than 0.003 mm Hg per cm. For pressure drops about ten times as high, only a thin sheet close to the wall reaches temperature equilibrium, but this fact affects only the total number of activated molecules reaching the wall, not the temperature coefficients.
Wall Effect in Falling Ball Method for Viscosity
Authors: Francis Alfred W.
Published: January 2005

The wall effect for balls falling in a vertical cylindrical tube in a viscous fluid has been studied and expressed as an empirical function of the ratio of radii of the ball and tube. This function agrees well with observations at least to a ratio of 0.83 as compared with 0.09, the limit of agreement of Ladenburg's formula. The wall effect is probably independent of the absolute radii of the ball and tube and only slightly dependent upon the absolute viscosity. The bottom effect is negligible. For liquids of high viscosity the revised formula is η=2gR2(ρ1−ρ2)(1−R/r)2.25/9u.
A Study of the Evaporation of Small Water Drops
Authors: Houghton H. G.
Published: January 2005

A theoretical expression for the evaporation of small spherical water drops in still air is developed from the general evaporation equation of Jeffreys. Experimental data for the evaporation of drops ranging from 25 to 2600 microns in diameter are obtained at several temperatures and relative humidities. After making approximate corrections for the cooling of the drops it is found that the results are in general agreement with the theoretical evapooration equation. Residual variations which are functions of the drop size and the difference between the water vapor density at the surface of the drop and at a distance from the drop are probably due to inaccuracies in the method used for computing the drop temperatures. The results of the paper furnish a means for computing the total time required for the complete evaporation of a drop of liquid water into a still atmosphere at any given temperature and relative humidity.
The Final Distribution of Retained Liquid in an Ideal Uniform Soil
Authors: Smith W. O.
Published: January 2005

If liquid, initially saturating the pores of a soil, is allowed to drain from that soil, no such complete drainage as occurs in a simple capillary tube is observed; large quantities of liquid are retained. The quantity of liquid held by the soil immediately after drainage gradually alters; it decreases to a stationary value and the liquid so held finally arranges itself in a stable distribution. Whatever be the distribution, the bounding liquid surfaces are capillary ones and subject to the laws of thermodynamics and capillarity; the Kelvin relation, in general determines the curvatures. The problem is considered for an ideal soil, that is an assemblage of spheres, of a single size, packed at random. There are in the ideal soil three types of distribution. First, there is a pendular region where the liquid is retained in the form of single rings of liquid wrapped around the axis of each pair of adjacent grains in contact. Second, there is a funicular region, which may be considered to arise by coalescence of the rings; we have two or more grain contacts imbedded in a single liquid mass, that is, webs of liquid enmeshing two or more grain contacts and which may involve many grains of the packing. There is, finally, a saturation region in which all pores are completely filled. The limits of each of these zones are determined. The funicular zone is a zone of hysteresis and all values between a normal minimum and complete saturation are usually possible. To calculate the normal minimum distribution the actual packing is replaced by an average packing of grains in hexagonal array and equally spaced to give the required porosity. The funicular distribution is now in the form of single rings wrapped around the axis of each pair of grains of the packing. The volume of each type of ring is determined in terms of (σ/ρghr), where σ is the surface tension of the liquid and ρ its density, r the grain radius, and h the height of the ring above a free liquid reference plane. The average volume of each type of ring is obtained for all rings confined between two given planes. From the average ring volume and the number of such in each cc of packed space, the total retention in each zone above saturation is found. The distribution, that is, the liquid retained in any lamina at a height h above the free liquid, is also given. The results are compared with the data of King.
Creep of Metals in Shear at High Temperatures
Authors: Everett Franklin L.
Published: January 2005

The properties of materials at high temperatures are receiving considerable study in the design of much industrial equipment. The present paper describes some fundamental considerations in this field by discussing the creep of metals in shear. Some theoretical and practical reasons for investigating creep in shear are given, test apparatus for this purpose is outlined, and some experimental information is included. Much more work in this type of study is desired and the paper may help to stimulate further research in this direction.
Simple Derivations of Some Important Relationships in Capillary Flow
Authors: Schofield Robert Kenworthy
Published: January 2005

Use is made of geometrical constructions to demonstrate the conditions under which a plot of V/πR3 against ½pR gives a unique curve independent of the value of R, and also to show how account can be taken of discrepancies due to modified flow near the wall of the tube. In a similar way, the reasoning from which the velocity gradient GW at the wall of the tube can be deduced from experimental figures for V, p and R has been set out in a geometrical form, which should be helpful to those to whom a pictorial representation makes a ready appeal. The deductions, though simple, involve no loss of generality. The data of Farrow, Lowe and Neale for two percent starch paste are considered by way of example, and it is shown that their form GW=(V/πR3)(N+3)  where  N=d (log V)/d (log p)of the equation for the velocity gradient at the wall has special advantages. Later work, by disclosing a wider basis, has shown that N need not be constant as they supposed, and also that, where modified flow occurs near the wall of the tube, V/πR3 becomes Vβ/πR3, the limiting value for large radii.
Potential Distribution About an Electrode on the Surface of the Earth
Authors: Muskat Morris
Published: January 2005

An analytical study is made of the potential distribution about an electrode on a stratified earth, from the point of view of developing special formulas appropriate for computation at small and large distances from the electrode. Power series in the distance for small distances and simple asymptotic expansions for large separations are derived first for a two layer earth, from integral expressions for the potentials. For graphical integration a transformation is derived which makes the integrals converge very rapidly. For a many layer earth a general method for deriving the power series for small distances is indicated. For large distances, general expansions are given in closed (Eq. (23)) and asymptotic forms (Eq. (24)) applying to all types of conductivity variation. Explicit expressions for the power series are given for a three layer earth with the middle layer of thickness equal to and twice that of the upper layer. Closed and very rapidly converging series of Hankel function expansions are then developed for the third layer having zero or infinite conductivities, with the thickness of the middle layer being equal to, twice and three times that of the upper layer. Thirty numerical cases have been computed and plotted as curves to illustrate the fundamental formulae developed. In an appendix general proofs are given for the asymptotic expansions of not only the type of integrals occurring in the present problem but also for integrals involving Weber and Hankel functions as well as the Bessel functions, and where these functions are of non-zero orders.
The Crystal Structure of Uranium
Authors: Wilson Thomas A.
Published: January 2005

A method capable of solving x-ray powder photographs derived from crystal structures of low symmetry has been described. By the use of this method, the crystal structure of uranium has been obtained. Uranium crystallizes according to space group C2h3 of the monoclinic system, with 2 atoms in each crystallographic cell. The dimensions of the cell are: a=2.829A, b=4.887A, c=3.308A. Axial ratios are: 0.5791 : 1 : 0.6771. The x-ray density of uranium is 19.05. The uranium atoms appear to be prolate spheroids with 3.425A as the major axis and 2.826A as the minor axis.
An X-Ray Study of Variations in the Structure of Wood Fiber Walls
Authors: Stillwell Charles W.
Published: January 2005

Characteristic x-ray diffraction patterns produced by transverse, radial and tangential sections of wood fibers have been discussed. There are two fundamental types of orientation of the micelles or fibrils in wood fibers: A, parallel to the fiber axis; B, parallel to each other, but on a spiral at a definite slope to the fiber axis. The deviation from either type may be qualitatively estimated from the diffraction pattern. For type B, the slope of the spiral may be measured with considerable accuracy. When large angles of slope of the micelles are indicated most wood fibers differ fundamentally from cotton. In wood fibers the average slope is at a definite angle to the fiber axis; the deviation is from Type B. In cotton fibers the average slope approaches 0°; the deviation is from Type A.
The Theory of the Psychrometer. I. The Mechanism of Evaporation
Authors: Arnold J. Howard
Published: January 2005

Neither the diffusional theory of Maxwell nor the convectional theory of August is capable of representing adequately the processes of evaporation and heat transfer occurring at the wet bulb. An examination of these processes with the aid of the Reynolds analogy between heat and vapor transfer by convection on one hand, and fluid friction on the other, indicates that the correct theory consists of a combination of the two older theories, in which a mechanism of convection plus conduction is postulated for both heat and vapor transfer. When the thermal diffusivity is equal to the material diffusivity, a special case occurs, for which all three theories give the same result. This condition is approximately satisfied for the case of water evaporating into air; other gases or liquids must therefore be used to discriminate among the various theories. Experiments with water and four organic liquids show that the new theory represents the facts very accurately, and may be made the basis of a sound system for the reduction of psychrometric observations.
Fluidities of Thixotropic Gels: Bentonite Suspensions
Authors: Ambrose H. A. , Loomis A. G.
Published: January 2005

Flow measurements on bentonite suspensions, showing both the property of thixotropy and of fluidity variable with shearing stress, were performed in capillary tubes, brass pipes, and a rotary consistometer of special design. The latter instrument was used to show that the structure of such gels must be broken down or built up until an equilibrium state of flow is attained to obtain reproducible measurements. No slippage at the walls was found in non-plug flow. Turbulent flow of bentonite suspensions was investigated in one-half and one-inch pipes. It is demonstrated that these materials behave as any viscous liquid, in the turbulent region, and that the volume of flow at any pressure gradient may be assumed to be the same as for water, without great error. The importance of obtaining equilibrium flow conditions for fluidity measurements is stressed.
Low Voltage Impulse Circuits
Authors: Snoddy L. B.
Published: January 2005

Three different types of low voltage circuits suitable for supplying impulse voltages in oscillographic work are discussed. These circuits use Thyratrons as the connecting and timing switches in place of the spark gaps ordinarily employed in transient investigations. Charged condensers are used as the source of voltage. Two circuits are of the single tube type and the third is a multiple tube system in which a number of condensers are charged in multiple and discharged in series by means of Thyratrons. Oscillograms of the voltage form obtainable in each case are given and the time lag of starting determined.
Thermal Conductivity of Acheson Graphite
Authors: Crary A. P.
Published: January 2005

Thermal conductivity of Acheson graphite is reported for the temperature range −150°C to +700°C. Cylindrical blocks of the material were placed above and below a flat electric heater and lateral losses balanced out by auxiliary coils wound on the surface of the sample. The results show a continual decrease in thermal conductivity with temperature over the entire range. The law, k/aC=A/T+B, proposed by Bidwell for certain other materials is found to hold accurately for graphite.
Some Physico-Mathematical Aspects of Nerve Conduction
Authors: Rashevsky N.
Published: January 2005

It has been shown previously by the author that, from the physical point of view, the process of propagation of the nerve impulse is essentially different from the propagation of other kinds of disturbances usually studied in physics. Instead of being described by a differential equation, this type of propagation leads to a simple integral equation. In the domain of the inorganic similar types of propagation are met in the spread of activation on the surface of passive metals. In the present paper the problem of such types of propagation is treated mathematically for two different cases. In the first case it is assumed, that the nerve is electrically uniform all along its length. In this case the final formula for the velocity of propagation reduces to a rather simple expression which applied to the ischiadicus of the frog, leads to a value of 15 meters per second for the velocity of propagation. In the second case the nerve sheath is assumed to be completely insulating, except at the Ranvier nodes, where its continuity is broken, so that the electrical properties of the nerve vary periodically along its length. For the second case a more complicated formula is obtained, which reduces to the first one, when the distance between the nodes tends to zero. Effects of possible distributed capacity are briefly discussed.
Diffusion Through a Membrane
Authors: Barnes Colin
Published: January 2005

An exact solution is obtained for the problem of diffusion through a membrane separating two stirred solutions of different concentrations. For a diffusion cell in which the two liquid containers have the same volume and for which the ratio λ (``effective'' volume of membrane : volume of liquid) is small compared with unity, the solution gives explicit expressions for the concentrations at any time in terms of the initial distribution of concentration in the membrane. Two cases are treated: (1) zero initial concentration in the membrane and in one of the liquids; (2) an initial linear concentration gradient connecting the concentrations in the two containers. The usual assumption of a linear gradient across the membrane during the whole course of diffusion will not lead to an appreciable error in a determination of a diffusion constant unless λ exceeds 0.1 or the time of diffusion is much shorter than in the usual practice. Since λ is about 0.02 in the usual type of diffusion cell the use of the simple expression based on a linear gradient cannot be in error. If, however, the preliminary treatment of the membrane fails to yield an initial linear gradient in it, an appreciable error will be made even with λ less than 0.02.
Some New Sedimentation Formulas
Authors: Wadell Hakon
Published: January 2005

This paper presents some new methods of computing the sedimentation radius. The methods are founded on a curve for spheres, experimentally determined and constructed on the basis of the coefficient of resistance as a function of Reynolds number. When the validity of Stokes' law ceases, the sedimentation radius obtained by Stokes' formula is graphically corrected. The amount of deviation of Stokes' law from experimental data of higher Reynolds numbers has been statistically determined. Some new formulas for computing the resistance and the radius of a sphere of a given terminal settling velocity are presented.
The Piezoelectric Properties of Quartz and Tourmaline
Authors: Fox Gerald W. , Fink George A.
Published: January 2005

The piezoelectric properties of quartz and tourmaline have been investigated through a study of the converse piezoelectric effect. In the case of quartz, the piezoelectric constant has been measured from point to point across the specimen. Considerable variation in the ``constant'' has been observed in different samples of quartz. Attention is called to difference between the motions of piezoelectric plates when subjected to static electric fields and when subjected to alternating electric fields.
The Flow of Compressible Fluids Through Porous Media and Some Problems in Heat Conduction
Authors: Muskat Morris
Published: January 2005

In Part I the general partial differential equations are derived for the flow of compressible liquids and of gases through porous media, on the basis of the generalized Darcy law that: for all homogeneous fluids the fluid velocity is directly proportional to the pressure gradient. The equation for compressible liquids turns out to be the Fourier heat conduction equation with the density as the dependent variable, while for gases a nonlinear parabolic equation is obtained. The steady state solutions for these equations for linear and plane radial flow are derived and discussed in Part II. The heat conduction equation, in polar coordinates with radial symmetry, for compressible liquids, is then solved in Part III for systems in which (a) the density is specified over both concentric circular boundaries of an annular region, (b) the density is given over one boundary and the normal derivative over the other, and (c) the normal derivative is given over both boundaries. For the last case a new elementary solution is introduced, not given in the standard English texts. The cases where the internal boundary reduces to an infinitesimal sink are also given explicit solutions. Applications are made to (1) production history from a well whose pressure is reduced discontinuously to its final value; (2) production history from a well whose pressure is lowered so that the fluid density at the well drops linearly with the time; (3) the pressure rise in a well after shutting in; (4) pressure decline in the ``East Texas'' oil field; (5) production decline from a single well at constant pressure in a closed reservoir; and (6) pressure decline in a closed reservoir drained at a constant rate by a central well. The Green's function, corresponding to a well displaced from the center of a closed reservoir, is derived and is applied to the problem of the interference between two wells draining the same circular reservoir. The solutions for all these problems correspond to similar heat conduction problems which have not been previously solved explicitly in the literature. In Part IV an approximation theory is given for the non-isothermal gas flow from a closed circular reservoir into a central well, and is illustrated by a numerical example showing the pressure and production decline for such a reservoir on a sudden lowering of the well pressure from an initially uniform value.
What is Oiliness?
Authors: Bridgeman Oscar C.
Published: January 2005

An analysis is made of the concept of oiliness and of the problems connected with the determination of the oiliness of oils. The major difficulty involves a separation of the effects of viscosity and oiliness since both effects enter into measurements made in practical devices and under practical conditions. On the basis of information obtained at the Bureau using several devices, a method is proposed for separating these two effects. This makes it possible therefore to investigate the effects of the pertinent variables on oiliness without the introduction of viscosity effects.
A New Type Long Period Vertical Seismograph
Authors: LaCoste Lucien J. B.
Published: January 2005

A single spring vertical motion seismograph of theoretically infinite period is described. Actual periods of over a minute have been obtained with a seismograph of this type while for a period of 37 seconds the period was found to be constant to within 1 second for a variation of 9° in the angle between the seismograph arm and the horizontal. A special type of spring is required. The method of winding such a spring is described. A possible method of temperature compensation is given.
Propagation of Elastic Waves in Ice. Part II
Authors: Ewing Maurice , Crary A. P.
Published: January 2005

Flexural waves. A seismograph, used to study propagation of explosion-generated waves in a sheet of ice on a lake, revealed the existence of flexural waves. These waves showed marked dispersion, the group velocity being represented approximately by the empirical formula U=221(en)½, where e is the thickness of the ice in feet and n is the frequency. A theoretical formula is developed by which the velocity of these waves may be calculated from the elastic constants of ice and water. Transverse waves. By a suitable orientation of the seismograph it was possible to detect transverse waves, polarized horizontally, in the sheet of ice. The velocity of transverse waves was found to be 6057 ft./sec. which checks within about three percent with the value of velocity calculated from the elastic constants of ice as reported in Part I.
The Alternating Stress Method for the Measurement of the Consistency of Very Stiff Materials
Authors: Bingham Eugene C. , Stephens Robert A.
Published: January 2005

Samples of rosin, abietic acid and pitch may be made to flow at temperatures as low as 20°C at low pressures and conveniently short periods of time, sufficient for fluidity determinations. Such a method as this one was devised in the hope of finding a much better control instrument for such materials. No evidence of plasticity was observed. The fluidity was found to be independent of the dimensions of the apparatus used. In the pressure range from 130 to 1800 g per cm2 no effect of change of pressure upon the fluidity was detected. A study of the effect of changes in pressure upon the flow of plastic materials is now being made.
The Behavior of a Copper Oxide Photoelectrolytic Cell When Used with Sinusoidally Varying Illumination
Authors: Meserve Wilbur E.
Published: January 2005

Each of the copper electrodes of the cell was coated chemically with a layer of cuprous oxide. The electrolyte used was a one percent solution of lead nitrate. With an amplifier and cathode-ray oscilloscope the open circuit e.m.f. of the cell was studied for sinusoidally varying illumination of one electrode. The frequency response, the spectral response, and the phase shift between e.m.f. and illumination were determined. A.c. bridge measurements showed that the capacitance of the cell was large and that the greater portion of it conforms to the relation for electrolytic capacitance, C=C0/f½. The capacitance increases with illumination. The results are interpreted in terms of an equivalent electrical network whose elements have values corresponding to those of the cell as measured with the bridge. The computed results for the network are in excellent agreement with the observed results for the cell throughout the whole frequency range (0 to 10,000) when it is assumed, (1) that the primary effect of illumination is to cause electrons to pass through the ``barrier layer'' from the oxide to the copper, and, (2) that the number of such electrons is linearly proportional to the intensity of the light. The results thus lead to the conclusion that the photoactivity of this cell is to be explained in the same manner as that of the dry cuprous oxide cell, except that the electrolyte takes the place of the front electrode in making contact with the oxide.
The Flexure Problem for Rectangular Beams with Slits
Authors: Gunder Dwight F.
Published: January 2005

Experimental and approximate theoretical studies, made at the United States Forest Products Laboratory, Madison, Wisconsin, show that the mean shearing stress in the neutral plane of a rectangular beam with symmetrical horizontal slits or checks extending along its lateral faces is less than that given by the usual engineering formulas; that is, there is a definite ``two-beam'' action which relieves the shearing stress in the portion of the beam weakened by the slits. This paper presents an exact solution of the flexure problem for a beam of such section and confirms the main features of the distribution of shearing stress found in the earlier investigation. The solution of the flexure problem requires the solution of Laplace's equation within the plane region coincident with a cross section of the beam, subject to certain boundary conditions. This solution is obtained by using the Schwartz-Christoffel transformation of a polygon onto a half-plane and solving the transformed boundary value problem. The exact solution is set up as an infinite series. To simplify the calculations two approximate solutions are also obtained, one of which is used in treating a numerical example.
Magnetic Susceptibility of Some Alloys of ``Gamma-Brass'' Structure
Authors: Smith Cyril Stanley
Published: January 2005

The change of diamagnetic susceptibility with composition of a number of phases of gamma-brass structure (Cu–Zn, Cu–Cd, Ag–Zn, Ag–Cd) has been determined. In each case when the phase makes its first appearance with low electron ratio, it is not strongly diamagnetic, but the increase in diamagnetism is approximately lineally dependent on the number of free electrons, and the strongest diamagnetism occurs at the limit of the gamma-phase with the highest electron ratio possible for the structure.
Further Studies on Mathematical Physics of Metabolizing Systems with Reference to Living Cells
Authors: Rashevsky N.
Published: January 2005

In previous papers we studied the effects of forces, produced by metabolism, on the mechanical stability of the metabolizing system. In this paper various other effects of those forces are discussed. First of all it is shown that, whenever those forces are of such a nature as to make the system unstable and cause its eventual division, their effect is also that of increasing the size of the system. This reminds of the relation between rate of growth and division in living cells. Further the effects of those forces on molecules and colloidal particles, present in the system, but not directly participating in metabolism, are studied. It is shown that those forces produce a nonhomogeneous distribution of those molecules and particles, and thus alter the structure and the physical constants of the system. For single molecules the effect is negligible; but for colloidal particles of a size above 10−5 cm it may be very large and may produce a concentration of those particles at the surface of the system, altering thus the permeability of the latter. Those effects are present only as long as the system metabolizes. This may have a bearing on the sudden change of permeability of living cells after death. Since, under the influence of those forces the permeability of a system becomes a function of the intensity of the metabolizing processes, the fundamental equations describing such systems are much more complicated than those studied hitherto. One particularly interesting feature is that those equations now possess in general not one, but several stable solutions, so that the specification of all the parameters, which determine the external conditions, does not determine the configuration of the system in a unique way. As shown previously, such a situation leads to various hysteresis phenomena. One type of such a hysteresis, particularly interesting from the point of view of possible biological applications, is illustrated on a numerical example. It consists in an irreversible transition of the system from a state of slower growth and greater stability into a state of more rapid growth and lesser stability, under the influence of certain reversible changes in the environment of the system.
Compressional Waves in Media with Complex Viscosity
Authors: Gemant A.
Published: January 2005

The author recently suggested the introduction of a complex viscosity in the theory of vibrations of materials which lie between the purely crystalline and the liquid state. This conception is utilized here in the theory of compressional waves in an infinite medium. One of the conclusions, namely, the decrease of the attenuation factor with increasing frequency, is in agreement with observations. Another conclusion is an increase of the propagation velocity with frequency. Both changes occur in the neighborhood of a certain characteristic frequency, given by the reciprocal of the so-called relaxation constant. Below this frequency range the material vibrates like a liquid; above this range like a crystal.
Dynamical Similarity Laws of the Mercury High Pressure Discharge
Authors: Heller G.
Published: January 2005

Dynamical similarity laws of the high pressure mercury vapor discharge have been set up. These laws are based on principles which determine characteristics of a high pressure discharge in thermal equilibrium. Characteristics of discharges can be determined by measurements on models if the model contains the same mass of mercury gas per cm and is supplied with the same wattage per cm of length of tube as the main construction. The temperatures of the walls of discharge tube should be the same. In formulating the above requirements self-absorption has been neglected. Experimental tests have shown the validity of the similarity theorems.
The Seepage of Water Through Dams with Vertical Faces
Authors: Muskat Morris
Published: January 2005

The method of hodographs, recently developed by Hamel for the analysis of ground-water flow systems containing free surfaces, is applied numerically to six cases of the seepage of water through dams in which the ratio of the inflow fluid head to the width of the dam at the base varied from 2.04 to 1.08. In one case the velocity distribution was computed both along the inflow and outflow faces, as well as along the base of the dam. The pressure and velocity distributions along the bases and the velocity distribution along the inflow faces were found for 5 other cases, in 4 of which the outflow fluid head was zero. The heights of the surfaces of seepage and the total fluxes were calculated for all six cases. These calculations show that the Dupuit-Forchheimer theory of the free surface and velocity distributions in gravity flow systems is definitely wrong, and that the extension of the empirical results of Wyckoff, Botset and Muskat, obtained with radial gravity flow systems, to linear systems is unjustified. The fluxes, however, given by this extension or the Dupuit-Forchheimer theory turn out to be in close agreement with those calculated by the exact theory. The evaluation of the fundamental integral over the argument of the modular elliptic function involved in the calculations is extended beyond the range given by Hamel and Gunther so as to include all real values of the modular elliptic function.
The Viscosity of Mixtures of Liquids at High Pressures
Authors: Dow R. B.
Published: January 2005

The effects of pressure and temperature change on the viscosity of organic, binary mixtures have been investigated by methods developed and used by P. W. Bridgman. Six mixtures have been examined over the entire concentration range at two temperatures, 30° and 75°C, and at pressures extending to 12,000 kg/cm2. The isobaric, log viscosity-concentration curves for n-hexane carbon disulphide, and n-hexane n-decane are linear at both temperatures, indicating that these mixtures obey Arrhenius' empirical equation for the viscosity of a binary mixture. It is believed that a comparatively simple type of interlocking among molecules occurs in these mixtures due to the effectively linear structure of the molecules and the absence of non-uniform molecular fields such as would cause some sort of association. For the remaining mixtures: n-hexane diethyl ether, n-hexane chlorobenzene, n-pentane benzene, and eugenol carbon disulphide, the corresponding viscosity isobars are more complex; irregularities occur in certain regions of concentration which vary with temperature and pressure. In these latter mixtures, the interlocking at high pressures is complicated by the structural differences of the component molecules and their effects. The viscosity of n-decane as a function of pressure and temperature has also been investigated. Density data at atmospheric pressure and 30° are included in the paper.
Internal Dissipation in Solids for Small Cyclic Strains
Authors: Wegel R. L. , Walther H.
Published: January 2005

This paper presents the results of investigations of dissipation of energy in vibrating solids, mostly metals, by means of longitudinal and torsional vibrations of cylindrical rods. The amplitudes of strain used have been kept between 10−5 cm/cm and 10−8 cm/cm, in which range the dissipation of energy is proportional to the square of the strain. The specific dissipative property of a material is expressed in three different ways: (1) Equivalent viscosity or the ratio of stress to dissipative component of strain rate; (2) hysteretic constant defined as the area in ergs of the cyclic stress-strain diagram; and (3) elastic phase constant defined as the ratio of specific elastic reactance to equivalent viscosity. Within a range of frequencies 100 to 100,000 cycles per second the results show that the hysteretic constant is proportional to some power Δ of the frequency, the numerical value of the exponent Δ varying between the limits − ⅓ and + ½, depending on the kind of material and its internal structural condition. Measurements made with longitudinal and torsional vibration indicate that dissipation is associated with dilatation as well as with pure shear. Preliminary studies are described showing the correlation between internal dissipation in metals and temperature hardness effects of annealing and aging.
Theory of Photoelasticity in Amorphous Solids
Authors: Mueller Hans
Published: January 2005

The photoelastic effect in amorphous solids is caused by two effects. The elastic deformations alter the Lorentz-Lorenz interaction between the dipoles, and in addition produce optical anisotropy of the atoms. For pressure the first effect creates positive birefringence, while the second effect gives negative birefringence. In most cases the second effect is larger. With increasing index of refraction the first effect increases faster than the second effect, and hence the photoelastic constants decrease and reversal of sign occurs. Measurements on glasses verify the theory. A uniform volume expansion of 1 percent increases the refraction of the oxygen ions by 0.4 percent and a strain of 1 percent creates an optical anisotropy of the 0 ion of about 0.7 percent. For the positive ions these effects are somewhat smaller.
The Determination of Arc Temperature from Sound Velocity Measurements. I
Authors: Suits Chauncey Guy
Published: January 2005

The dependence of the velocity of sound on gas temtemperatures is utilized to determine the temperature of the copper arc in air at atmospheric pressure. The sound ``wave'' produced from a condensed spark discharge in air is passed through the stabilized arc column and received by a second spark discharge, acting as a microphone. The time interval is measured on the cathode-ray oscillograph. When the arc length and, hence, sound path, are varied, the time interval varies approximately linearly. The resultant sound velocity free from end corrections is 1.39×105 cm sec.−1, for which the arc temperature is calculated to be 4100±300°K when corrections for dissociation and changes in specific heat are taken into account. Time intervals are measured for a constant arc length of 9 cm for currents between 3 and 26 amperes, and it is found that the velocity (and temperature) is independent of current within the experimental error. Conclusions based on the results are: (1) The electron density is 0.6×1012; (2), the partial pressure of Cu vapor is 7.5×10−7; and (3), the ``effective ionization potential'' of the arc gas is 12.3 volts.
The Temperature Variation of the Photoelectric Emission from Thorium Oxide
Authors: Marchant J. H.
Published: January 2005

The photoelectric emission from a platinum filament coated with thorium oxide seems to be due chiefly to that part of the spectrum lying between 2500A and 3100A. An increase in the photoelectric emission from the thorium-oxide-coated platinum filament was observed with increasing temperature from 23°C up to about 200°C, and a decrease from the same filament with increasing temperature from 200°C to about 400°C. A definite photoelectric emission was observed from this filament whether the corresponding thermionic current was saturated or not. No photoelectric fatigue was observed.
Magnetic Hysteresis at Low Flux Densities
Authors: Ellwood W. B.
Published: January 2005

The energy loss per cycle in a ferromagnetic material subjected to small alternating fields is sometimes separated into three parts; the first due to eddy current loss, the second to hysteresis presumed to follow Rayleigh's laws at these flux densities. The origin of the remainder is unknown and is the subject of much controversy; it has been variously termed ``magnetic viscosity,'' ``after effect'' and ``square law hysteresis.'' In studying energy loss in a ring of compressed iron dust, hysteresis loops have been measured ballistically by a new method with a relative error in Bm as low as 0.01 percent. The range in maximum flux density is from 2 to 100 gauss. The loops are lenticular and very slender, Bm being about 1500 times the remanence for the smallest loop. The smaller loops are at flux densities considerably below those investigated by Rayleigh. His findings as to variation of area, of remanence, and of permeability with loop amplitude are confirmed and extended through the new range of flux densities, though the shape of the loops is not as simple as that he proposed. The energy loss per cycle is proportional to Bm3 while the remanence is proportional to Bm2. The ballistic measurements have been compared with a.c. bridge measurements on the same specimen. The loss of unknown origin is not included in the hysteresis loss measured ballistically. Comparison is made between the third harmonic induced voltage computed by a Fourier series analysis of the ballistic loops and the harmonic actually generated by the specimen. Agreement is found between the measured and the computed values. Possible explanations of the discrepancy between the ballistic observed energy losses and a.c. findings are discussed.
The Motion of a Viscous Fluid Under a Surface Load
Authors: Haskell N. A.
Published: January 2005

A formal solution is given for the motion of a highly viscous fluid when a symmetrical pressure is applied at the surface. This is applied to the subsidence of a cylindrical body of constant thickness and to the recovery of the fluid after removal of a load. Applying the latter case to the plastic recoil of the earth after the disappearance of the Pleistocene ice sheets, it is found that the geological data imply a kinematic viscosity of the order of 3×1021 c.g.s. units.
Heat Treatment of Magnetic Materials in a Magnetic Field I. Survey of Iron-Cobalt-Nickel Alloys
Authors: Dillinger Joy F. , Bozorth Richard M.
Published: January 2005

The changes that occur in the magnetic properties of iron-cobalt-nickel alloys when they are annealed in a magnetic field, have been investigated for a series of these alloys. The maximum change for the iron-nickel alloys occurs between 65 and 70 percent nickel and is evidenced by a large increase in maximum permeability and a hysteresis loop of rectangular shape. All of the alloys with Curie points above 500°C and with no phase transformation have their properties similarly changed. Thorough preliminary annealing enhances the effect. With an extreme preliminary anneal of 1400°C for 18 hours specimens of 65 permalloy have been obtained with the record value of maximum permeability of 600,000. The magnetic characteristics of materials treated in this way are relatively insensitive to stress. These magnetic characteristics are, however, highly anisotropic; the maximum permeability in one direction is as much as 150 times as large as that at right angles.
The Relation Between Absolute Viscosity and Penetration of Asphaltic Bitumens
Authors: Saal R. N. J. , Labout J. W. A.
Published: January 2005

The relationship between absolute viscosity and penetration for asphaltic bitumens has been reinvestigated. With purely viscous materials in a wide range of penetration figures (5 to 250) a general relation exists. It is found, however, that the depth of penetration depends somewhat upon the conditions under which the measurements are made. Inadequate adhesion of the bitumen to the penetration needle increases the penetration. This effect, however, is not great and is the same for all purely viscous bitumens of the same penetration. Penetration depth determinations were also made with elastic bitumens. Here the final penetration depth is increased by interruptions of the determination as a consequence of the dissipation of the elastic tension during interruption. It is concluded that Traxler, Pittman, and Burns in their experiments have overlooked the elastic behavior of some of their bitumens and that therefore their criticism of the relation deduced by us between penetration and absolute viscosity is not valid.
The Rheology of Raw Rubber
Authors: Mooney M.
Published: January 2005

A viscometer of the rotating cylinder type is described which is applicable to rheological measurements of raw rubber. To make the instrument operative with such material the surfaces of the cylinders are fluted, to form rough, gripping surfaces; and pressure devices are added which compress and confine the rubber between the cylinders. At low or moderate stresses the rate of shear in hot, raw rubber follows the equation α̇=Aσ2. At higher stresses the rate of shear increases more rapidly with increasing stress. The elastic recovery of hot, raw rubber requires over 5 hours for completion. During most of this time the recovery angle follows the law α=A+B log t. The modulus of rigidity in small deformations of hot, raw rubber is only slightly less than that of soft, cured rubbers at room temperature. The viscosity of a sample of hot, raw rubber in vibration is many times less than the viscosity of the same sample in continuous shear.
The Double Mobility of Some Non-Newtonian Fluids with Particular Reference to Cellulose Nitrate Sols
Authors: de Waele A. , Dinnis G.
Published: January 2005

The ratio of the mobility of nitrocellulose solutions at high shearing stresses to the mobility at low shearing stresses, where there exists in fact true fluidity, is called the ``mobility ratio.'' This mobility ratio may be very high for certain ``medium'' and ``high viscosity'' nitrocottons, but it does not necessarily prove to be a figure proportional to the usually accepted ``viscosity.'' Thus mixtures of ``high'' and ``low'' viscosity nitrocottons may be so blended that, although showing similar low shearing stress viscosities with the falling ball, one will show at high shearing stresses much higher viscosity than the other. Certain ``low'' viscosity nitrocottons appear to show a nearly constant true viscosity at all rates of shear. The two mobilities show significant differences in technical behavior. Thus under given conditions of use, such as spraying, brushing, roller coating, etc., the high stress mobility determines what may be called the solvent demand of the sol, whereas the viscosity at low stresses indicates the characteristics to be expected after application.
Directional Characteristics of Any Antenna Over a Plane Earth
Authors: Hansen W. W.
Published: January 2005

Simple expressions for the field as a function of direction at distances of many wave-lengths from any antenna above a plane earth are obtained. Except near the surface of the earth the field varies as 1/r. In agreement with results of others it is found that on the surface of the earth for values of kr, (k=2π/λ), large compared to unity and yet small compared to the (complex) dielectric constant, the vertical component of the field varies as 1/r while if the distance is large compared to the dielectric constant the field decreases as 1/(kr)2. The various constants etc., depending on antenna form and ground characteristics, are shown to be connected with quantities previously used for the determination of radiation resistance so that the same numerical work used to find the total radiation from an antenna also determines its directional characteristics.