THE BELL SYSTEM " 



TECHNICAL JOURKfAL 



A JOURNAL DEVOTED TO THE 



SCIENTIFIC AND ENGINEERING 



ASPECTS OF ELECTRICAL 



COMMUNICATION 



EDITORS 



R. W. King 



J. O. Perrine 



P. B. Jewett 

 O. E. Buckley 

 S. Bracken 



EDITORIAL BOARD 



W. H. Harrison 

 A. B. Clark 

 M. J. Kelly 

 W. Wilson 



O. B. Blackwell 

 H. S. Osborne 

 F. A. Cowan 



TABLE OF CONTENTS 



AND 



INDEX 



VOLUME XX 



1941 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



