PHE BELL SYSTEM 



Jechnical ournai 



»E VOTED TO THE SC I E N T I F IC^^^ AND ENGINEERING 

 SPECTS OF ELECTRICAL COMMUNICATION 



OLUME XXXI SEPTEMBER 1952 NUMBERS 



^&- ' 



Auotmatic Switching for Nationwide Telephone Service 



A. B. CLARK AND H. S. OSBORNE 823 



Fundamental Plans for Toll Telephone Plant J. J. pilliod 832 



Nationwide Numbering Plan w. h. nunn 851 



Automatic Toll Switching Systems f. f. shipley 860 



Mathematical Theory of Laminated Transmission Lines — ^Part I 



SAMUEL p. morgan, JR. 883 



Electrical Noise in Semiconductors h. c. Montgomery 950 



important Design Factors Influencing ReUabihty of Relays 



J. R. FRY 976 



Lnpedance Bridges for the Megacycle Range n. t. wilhelm 999 



Abstracts of Bell System Papers Not Published in this Journal 1013 

 Contributors to this Issue 1020 



COPYRIGHT 1952 AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



