THE BELL SYSTEM TECHNICAL JOURNAL 



ADVISORY BOARD 



S. BRACKEN, Chairman of the Board, 



Western Electric Company 



F. R. KAPPEL, President, Western Electric Company 



M . J. KELLY, President, Bell Telephone Laboratories 



E. J. McNEELY, Vice President, American Telephone 

 and Telegraph Company 



EDITORIAL COMMITTEE 



E. I. GREEN, Chairman 



A. J. B U S C H F. R. L A C K 



W. H. DOHERTY W. H. NUNN 



G.D.EDWARDS H, I. R O M N E S 



J. B. FISK H.V.SCHMIDT 



R. K. HON AM AN G. N. T H AY E R 



EDITORIAL STAFF 



J. D. T E B O, Editor 



M. E. STRIEBY, Managing Editor 



R. L. SHEPHERD, Production Editor 



THE BELL SYSTEM TECHNICAL JOURNAL is published six times 

 a year by the American Telephone and Telegraph Company, 195 Broadway, 

 New York 7, N. Y. Cleo F. Craig, President; S. Whitney Landon, Secretary; 

 John J. Scanlon, Treasurer. Subscriptions are accepted at $3.00 per year. 

 Single copies are 75 cents each. The foreign postage is 65 cents per year or 11 

 cents per copy. Printed in U. S. A. 



