VOLUME XV 



JULY, 1936 NUMBER 3 



THE BELL SYSTEM 



TECHNICAL JOURNAL 



DEVOTED TO THE SCIENTIFIC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



A Laplacian Expansion for Hermitian-Laplace Functions of 



High Order— £. C. Molina 355 



The Relation Between Penetration and Decay in Creosoted 



Southern Pine Poles— i?. H. Colley and C. H. Amadon 363 



Tandem Operation in the Bell System— F. M. Bronson . . 380 



A Non- Directional Microphone — 



R. N. Marshall and F. F. Romanow 405 



Oscillations in Systems with Non-Linear Reactance — 



R. V. L. Hartley 424 



Oscillations in an Electromechanical System — 



L. W. Hussey and L. R. Wrathall 441 



A New Type of Underground Telephone Wire— Z>. A. Quarles 446 



Technical Digests — 



Effect of Electric Shock on the Heart — 



I. P. Ferris, B. G. King, P. W. Spence and H. B. Williams 455 



A New High-Efficiency Power Amplifier for Modulated Waves — 



W. H. Doherty 469 



Abstracts of Technical Papers 476 



Contributors to this Issue 480 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



50c per Copy 



$1.50 per Year 



