HE BELL SYSTEM 



Uechnical ournal 



[voted to the scientific^^^ and engineering 

 pects of electrical communication 



ADVISORY BOARD 



A. B. GoETZE M. J. Kelly 



E. J. McNebly 



EDITORIAL COMMITTEE 



B. McMiLLAX, Chairman 

 S. E. Brillhart E. I. Green 



A. J. BUSCH H. K. HONAMAN 



L. R. Cook H. R. Huntley 



A. C. DicKiEsoN F. R. Lack 



R. L. DiETzoLD J. R. Pierce 



K. E. Gould G. N. Thayer 



EDITORIAL STAFF 



J. D. Tebo, Editor R. L. Shepherd, Production Editor 



KANSAS CITY, MO. 

 INDEX PUBl/- y 



FFR 1 '^ 1Q57 

 VOLUME XXXV I i^u ±o \^ut 



1956 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



