VOLUME XVra APRIL, 1939 NUMBER 2 



THE BELL SYSTEM 



TECHMC AL JOURNAL 



DEVOTED TO THE SCIENTinC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



Some Ceramic Manufacturing Developments of the Western 

 Electric Company — A. G. Johnson and L, I, Shaw . . . 255 



The Production of Ultra-High-Frequency Oscillations by 

 Means of Diodes — F. B, Llewellyn and A. E. Bowen . . 280 



A Representation of the Sunspot Cycle — C. N, Anderson . . 292 



The Number of Impedances of an n Terminal Network 



— John Riordan 300 



Copper Oxide Modulators in Carrier Telephone Systems 



—R. S. Caruthers 315 



Some Applications of the Type "J" Carrier System 



— L. C. Starbird and J. D. Mathis 338 



Line Problems in the Development of the Twelve-Channel 

 Open-Wire Carrier System 



— L. Af. Ilgenfritz, R, N, Hunter and A, L. Whitman 363 



Abstracts of Technical Papers 388 



Contributors to this Issue . 391 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



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