Index of content:
Volume 11, Issue 5, 01 May 1940
11(1940); http://dx.doi.org/10.1063/1.1712778View Description Hide Description
Forces created when loads are applied to the platforms of automatic weighing mechanisms are frequently balanced by the rotation of pendulums. In certain types of pendulum‐controlled scales it is desired that the relationship between the load applied and the angle turned by the pendulums be essentially linear. Even though the cams used for pendulum rotation are sectors of circles, it has been found experimentally that by the proper adjustment of various pendulum parameters, linear performance can be approximated to within less than 0.025 percent of scale capacity. An analysis of the forces involved in such systems leads to a mathematical statement of pendulum performance. Furthermore, experimental results confirm quantitatively the operation predicted by analysis. A method of selecting parameters for optimum performance is presented.
11(1940); http://dx.doi.org/10.1063/1.1712779View Description Hide Description
From the Cooper‐Hewitt mercury lamp of 1902, operating at a pressure of 0.0003 atmosphere and an efficiency of 18 lumens per watt, there have been developed lamps in hard glass and in fused quartz with pressures up to 200 atmospheres and efficiencies of 40 lumens per watt and above. At the highest pressures water‐cooling is required, and a careful coordination of the designs of lamp, jacket, and ballast is required for successful operation. Brightness‐distribution and spectral‐energy data are given for the A‐H6 and two experimental water‐cooled lamps. Photoengraving, television, and searchlight applications of the A‐H6 water‐cooled lamp are discussed.
11(1940); http://dx.doi.org/10.1063/1.1712782View Description Hide Description
11(1940); http://dx.doi.org/10.1063/1.1712783View Description Hide Description
From a survey of available data on the density of fluid lubricants as a function of pressure and temperature, the following empirical equation has been derived:ρ is the density at a given pressure (gage) p and temperaturet; ρ0 is the corresponding density at atmospheric pressure. The constants a and b are evaluated over a temperature range extending from 20° to 220°F and the density equation is valid over a pressure range of 50,000 lb./in.2. While the equation was derived from data on mineral oils it has been found to hold equally well for animal, vegetable, and fish oils. The variation of density with pressure is independent of the nature of the oil.
11(1940); http://dx.doi.org/10.1063/1.1712784View Description Hide Description
11(1940); http://dx.doi.org/10.1063/1.1712785View Description Hide Description
Some uses of radioactive phosphorus in soil and fertilizer studies have been investigated. The necessary apparatus, the technique, and the accuracy of determining radioactive phosphorus in soils, solutions and plant ashes are described and discussed, and several examples of its application in agricultural problems are given. These include measurements of the rate of sorption of phosphorus by soils, fertilizer‐placement studies, and measurements of the movement of applied phosphorus through a soil.