VOLUME Xn OCTOBER, 1933 number 4 



THE BELL SYSTEM 



TECHNICAL JOURNAL 



DEVOTED TO THE SCIENTIFIC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



Loudness, Its Definition, Measurement and Calculation 



—Harvey Fletcher and W. A. Munson 377 



Effect of Atmospheric Humidity and Temperature on 

 the Relation between Moisture Content and 

 Electrical Conductivity of Cotton — 



Albert C. Walker 431 



Classification of Bridge Methods of Measuring 

 Impedances— John G. Ferguson 452 



Some Theoretical and Practical Aspects of Noise 



Induction— i?. F. Davis and H. R. Huntley . . .469 



Audio Frequency Atmospherics — 



E. T. Burton and E. M. Boardman 498 



Certain Factors Limiting the Volume Efficiency of 

 Repeatered Telephone Circuits- 

 Leonard Gladstone Abraham 517 



Abstracts of Technical Papers 533 



Contributors to this Issue S38 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



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