Volume 4, Issue 2, 01 February 1933
Index of content:
Infrared Absorption Spectra of Certain Organic Compounds, Including the Principal Types Present in Gasoline4(1933); http://dx.doi.org/10.1063/1.1745157View Description Hide Description
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.
4(1933); http://dx.doi.org/10.1063/1.1745158View Description Hide Description
Five general properties of steady temperatures in solids of arbitrary shape are derived here. Although the derivations are mathematical they depend almost solely on the very fundamentals of the mathematical theory of heat conduction. The solid has any portion of its surface held at a fixed temperature distribution and the rest exposed to gas. The rate of transfer of heat between gas and surface is assumed to be any function of the position of the point and the temperature of the surface, for a given state of the gas. For a fixed temperature this function is called the emissivity. Briefly stated, the important properties are: I. In two geometrically similar solids exposed to the same surface temperature conditions at corresponding points, except that their emissivities are inversely proportional to their sizes, the temperatures at corresponding points are equal. I(a). If the entire surfaces of two geometrically similar solids are given fixed temperature distributions the temperatures at corresponding points are equal everywhere if they are equal on the surfaces. II. An increase in the size of a solid causes the same temperature change as an increase in its emissivity. IV. An increase in the size of a solid causes an increase in the temperature at each point if the solid is receiving heat from the gas, and a decrease if the solid is losing heat to the gas. V. From Newton's law of surfaceheat transfer there follows a linear relation between the steady temperature at any point and the uniform temperatures of the gas and the fixed‐temperature surface. These properties are discussed at the end of the paper. Some of the results of IV seem contrary to expected results.
4(1933); http://dx.doi.org/10.1063/1.1745159View Description Hide Description
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.
4(1933); http://dx.doi.org/10.1063/1.1745160View Description Hide Description
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 averageanode 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 Depth4(1933); http://dx.doi.org/10.1063/1.1745161View Description Hide Description
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 . 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.
4(1933); http://dx.doi.org/10.1063/1.1745162View Description Hide Description