VOLUME XVn JULY, 1938 NUMBER 3 



THE BELL SYSTEM 



TECHNICAL JOURNAL 



DEVOTED TO THE SCIENTinC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



Hertz, the Discoverer of Electric Waves — Julian Btanchard . 327 



Instruments for the New Telephone Sets — W. C. Jones . . 338 



Transmission Features of the New Telephone Sets 



—A. H. Inglis 358 



Spectrochemical Analysis in Communication Research 



— Beverly L. Clarke and A, E. Ruehle 381 



High Speed Motion Picture Photography — W, Herriott . . . 393 



An Optical Harmonic Analyzer — H. C. Montgomery .... 406 



Magnetic Shielding of Transformers at Audio Frequencies 



—W. G, Gustafson 416 



Coaxial Cable System for Television Transmission 



—M. E. Strieby 438 



Stabilized Feedback Oscillators — G. H, Stevenson .... 458 



The Discovery of Electron Waves — C. J. Davisson .... 475 



Abstracts of Technical Papers 483 



Contributors to this Issue 486 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



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