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THE BELL -xSYSTEM 



TECHNICAL JOURNAL 



A JOURNAL DEVOTED TO THE 



SCIENTIFIC AND ENGINEERING 



ASPECTS OF ELECTRICAL 



COMMUNICATION 



EDITORIAL BOARD 



J. J. Carty Bancroft Gherardi F. B. Jewett 



H. P. Charlesworth E. H. Colpitis 



L. F. Morehouse H. D. Arnold 0. B. Blackwell 



W. H. Harrison Philander Norton, Editor 



VOLUME VIII 

 1929 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



