5LUME XV 



APRIL, 1936 



NUMBER 2 



THE BELL SYSTEM 



TECHNICAL JOURNAL 



DEVOTED TO THE SCIENTIFIC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



The Reliability of Short- Wave Radio Telephone Circuits — 



R, K. Potter and A. C. Peterson, Jr. 181 



Spontaneous Resistance Fluctuations in Carbon Microphones 

 and Other Granular Resistances — 



C. J. Christensen and G. L. Pearson 197 



Contemporary Advances in Physics, XXX — The Theory of 



Magnetism — Karl K. Darrow 224 



The Proportioning of Shielded Circuits for Minimum High- 

 Frequency Attenuation — 



E. I. Green, F. A. Leibe and H. E. Curtis 248 



Hyper-Frequency Wave Guides — General Considerations and 



Experimental Results— G. C. Southworth 284 



Hyper-Frequency Wave Guides — Mathematical Theory — 



John R. Carson, Sallie P. Mead and S. A. Schelkunoff 310 

 A Magneto-Elastic Source of Noise in Steel Telephone Wires — 



W. O. Pennell and H. P. Lawther 334 

 An Extension of Operational Calculus — John R. Carson . . 340 



Technical Digest — 



Determination of the Corrosion Behavior of Painted Iron and the 



Inhibitive Action of Paints — R. M. Burns and H. E. Haring . . 343 



Abstracts of Technical Papers 349 



Contributors to this Issue 351 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



