VOLUME XVm OCTOBER, 1939 number 4 



THE BELL SYSTEM 



TECHMCAL JOURNAL 



DEVOTED TO THE SCIENTIFIC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



Experience in Applying Carrier Telephone Systems to Toll 

 Cables— PT. B. Bedell, G. B. Ransom and W. A. Stevens 547 



The Toronto-Barrie Toll Cable 



— M. J, Aykroyd and D. G. Geiger 588 



The Computation of the Composite Noise Resulting from Ran- 

 dom Variable Sources — E. Dietze and W. D. Goodale, Jr. 605 



Load Rating Theory for Multi-Channel Amplifiers 



—B. D. Holbrook and J. T. Dixon 624 



The Quantum Physics of Solids, I. The Energies of Electrons 

 in Crystals — W. Shockley 645 



DialClutchof the Spring Type— C.F. PTiebusc/i 724 



Abstracts of Technical Papers 742 



Contributors to this Issue . 747 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



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