THE BELL SYSTEM TECHNICAL JOURNAL 



ADVISORY BOARD 



8. BRACKEN, President, Western Electric Company 



F. R. K A P P E L, Vice President, American Telephone 

 and Telegraph Company 



M. J. K E I.L Y, President, Bell Telephone Laboratories 



EDITORIAL COMMITTEE 



E. I. GREEN, Chairman 



A. J. BUSCH F. R. LACK 



W. H. DOHERTY J. W. McRAE 



G. D. EDWARDS W. H. NUNN 



,. B. FISK H. I. ROMNES 



[. K. HONAMAN 



EDITORIAL STAFF 



H. V. SCHMIDT 



J. D. T E B O, Editor 



M. E. 8 T R I E B Y, Managing Editor 



R. L. SHEPHERD, Production Editor 



THE BELL SYSTEM TECHNICAL JOURNAL is published six time* 



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

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

 Alexander L. Stott, 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. 



