VOLUME XVn APRIL, 1938 NUMBER 2 



THE BELL SYSTEM 



TECHNICAL JOURNAL 



DEVOTED TO THE SCBENTinC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



Studies of Telephone Line Wire Spacing Problems 



— y. A. Carr and F. V, Haskell 195 



Variable Equalizers — H. W. Bode 229 



An Explanation of the Common Battery Anti-sidetone Sub- 

 scriber Set— C. O. Gibbon 245 



The Occurrence and Effect of Lockout Occasioned by Two 



Echo Suppressors — Arthur W. Horton, Jr 258 



Characteristic Time Intervals in Telephonic Conversation 



— A. C. Norwine and O, J, Murphy 281 



Radioactivity — Artificial and Natural — Karl K. Darrow . . . 292 



Abstracts of Technical Papers 319 



Contributors to this Issue 324 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



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