unjiiu i-iorary 



Kansas Citv,, M«k 



VOLUME XXIX JULY, 1950 no. 3 



THE BELL SYSTEM 



TECHNICAL JOURNAL 



DEVOTED TO THE SCIENTIFIC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



Principles and Applications of Waveguide Transmission 



G. C. Southworth 295 



Memory Requirements in a Telephone Exchange 



C. E. Shannon 343 



Matter, A Mode of Motion R.V.L. Hartley 350 



The Reflection of Diverging Waves by a Gyrostatic Mediimi 



R. V. L. Hartley 369 



Traveling-Wave Tubes (Third InstaUment) ..J. R. Pierce 390 



Technical Publications by Bell System Authors Other than 

 in the Bell System Technical Journal 461 



Contributors to this Issue 468 



50i Copyright, 1950 $1.30 



per copy American Telephone and Telegraph Company per Year 



