THE BELL SYSTEM TECHNICAL JOURNAL 



PUBLISHED SIX TIMES A YEAR BY THE 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



195 B R O AD WAY, NEW YORK 7, N. Y. 



CLEO F. CRAIG, President 



CARROLL O. BICKELHAUPT, Secretary 



DONALD R. BELCHER, Treasurer 



EDITORIAL BOARD 



F. R. KAPPEL O. E. BUCKLEY 



H.S.OSBORNE M.J.KELLY 



J. J. PILLIOD A.B.CLARK 



R, BOWN D. A. QUARLES 



F. J. FE ELY 



PHILIP C.JONES, Editor 

 M. E. STRIEBY, Managing Editor 



SUBSCRIPTIONS 



Subscriptions are accepted at $3.00 per year. Single copies are 75 cents each. 

 The foreign postage is 65 cents per year or 1 1 cents per copy. 



PRINTED IN U.S.A. 



