I3J_ 



VOLUME XXVII OCTOBER, 1948 no. 4 



Public ' ibrary 



Kan&tis City, McS 



THE BELL SYSTEM 



TECHNICAL JOURNAL 



DEVOTED TO THE SCIENTIFIC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



Equivalent Circuits of Linear Active Four-Terminal Net- 

 works L,C. Peterson 593 



A Mathematical Theory of Communication (Concluded) 



C. E. Shannon 623 



Transients in Mechanical Systems J, T, Muller 657 



Maximally-Flat Filters in Wave Guide . .W.W. Mumford 684 



Transient Response of an FM Receiver M.K. Zinn 714 



Transverse Fields in Traveling- Wave Tubes . .J,R, Pierce 732 



Abstracts of Technical Articles by Bell System Authors. . . 747 



Contributors to this Issue 752 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



50^ per copy $1.50 per Year 



