HE BELLSYSTEM 



Jechnical journal 



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



• ."^ ,1 



SPECTS OF ELECTRICAL COMMUNICATION ' /^ . 



^^^« . , — 



OLUME XXXI MAY 1952 "%^UMBER 3 



- Present Status of Transistor Development 



I 



J. A. MORTON 411 



An Experimental Electronically Controlled Automatic Switching 



System w. a. malthaner and h. earle vaughan 443 



New Techniques for Measuring Forces and Wear in Telephone 

 Switching Apparatus 



WARREN p. MASON AND SAMUEL D, WHITE 469 



A Comparison of Signalling Alphabets e. n. gilbert 504 



Principal Strains in Cable Sheaths and Other Buckled Surfaces 



I. L. HOPKINS 523 



A New Recording Medium for Transcribed Message Services 



JAMES Z. MENARD 530 



Introduction to Formal Realizability Theory-II 



BROCKWAY MCMILLAN 541 



Abstracts of Bell System Technical Papers not Published in this 



Journal 601 



Contributors to This Issue 608 



COPYRIGHT 1952 AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



