Abstracts of Technical Articles by Bell System Authors (01 July 1947)

Cent nickel), tension (ff) decreases resistivity, and magnetic field (H) increases it. Domain theory predicts the ratio c / H at which the resistivity is equal to that of the unmagnetized specimen, and the theory is accurately confirmed. Measurements are made in transverse as well as longitudinal magnetic fields, and the difference between the resistances so measured is shown to be independent of the distribution of domains in the unmagnetized state; the erratic results reported in the literature are thus explained and avoided. When magnetostriction is positive, the limiting changes of resistivity with field and tension are sometimes found to be different; this is shown to be caused by the variation of magnetostriction with crystallographic direction. 

A Wide-Tuning-Range Microwave Oscillator Tube} JOHN W. CLARK and ARTHUR L. SAMUEL. This paper describes a reflex-type velocity-variation oscillator tube with a wide tuning range in the microwave band. The tube will oscillate from 2000 to 13,000 megacycles, b u t practical tuning considerations limit the band in any one circuit to a two-to-one frequency range. 

The problems involved in the design and a description of the various elements are given. Accelerated Ozone Weathering Test for Rubber.5 JAMES CRABTREE and A. R. KEMP. Light-energized oxidation and cracking by atmospheric ozone are the agencies chiefly responsible for the deterioration of rubber outdoors. Since these processes are separate and distinct, it is proposed to distinguish between them in the evaluation of rubber for resistance to weathering.