HE BELL SYSTEM 



Jechnical fournal 



VOTED TO THE SC I E N T IFIC^W>^ AND ENGINEERING 

 PECTS OF ELECTRICAL COMMUNICATION 



LUME XXXVI MAY 1957 NUMBER 3 



Radio Propagation Fundamentals kenneth bullington 593 



A Reflection Theory for Propagation Beyond the Horizon 



H. T. FRnS, A. B. CBAWFORD, D. C. HOGG 627 



Interchannel Interference Due to Klystron Pulling 



H. E. CURTIS AND S. O. RICE 645 



Instantaneous Companding of Quantized Signals 



BERNARD SMITH 653 



An Electrically Operated Hydraulic Control Valve 



J. W. SCHAEFER 711 



Strength Requirements for Round Conduit g. f. weissmajtn 737 



Cold Cathode Gas Tubes for Telephone Switching Systems 



M. A. TOWNSEND 755 



Activation of Electrical Contacts by Organic Vapors 



L. H. GERMER and J. L. SMITH 769 



Bell System Technical Papers Not Published in This Journal 813 



Recent Bell System Monographs ' *V>v' ^^^ 



Contributors to This Issue \\\' rf iqc7 ^^^ 



COPYRIGHT 1957 AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



