THE BELL SYSTEM 



TECHNICAL JOURNAL 



VOLUME XXIX, 195 



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Table of Contents 

 January, 1950 



Traveling- Wave Tubes — /. R. Pierce 1 



Communication in the Presence of Noise — Probability of Error for Two 



Encoding Schemes — S. 0. Rice 60 



Realization of a Constant Phase Difference — Sidney Darlington 94 



Conversion of Concentrated Loads on Wood Crossarms to Loads Dis- 

 tributed at Each Pin Position — R. C. Eggleston 105 



The Linear Theory of Fluctuations Arising from Diifusional Mecha- 

 nisms — An Attempt at a Theory of Contact Noise — /. M. Richard- 

 son 117 



April, 1950 



Error Detecting and Error Correcting Codes — R. W. Hamming 147 



Optical Properties and the Electro-optic and Photoelastic Effects in 



Crystals Expressed in Tensor Form — W. P. Mason 161 



Traveling- Wave Tubes [Second Installment] — /. R. Pierce 189 



Factors Affecting Magnetic Quality — R. M. Bozorth 251 



JULY, 1950 



Principles and Applications of Waveguide Transmission — G. C. South- 

 worth 295 



Memory Requirements in a Telephone Exchange — C. E. Shannon .... 343 



Matter, A Mode of Motion— 7^. V. L. Hartley 350 



The Reflection of Diverging Waves by a Gyrostatic Medium -R. V . L. 



Hartley 369 



Traveling- Wave Tubes [Third Installment] — /. R. Pierce 390 



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