VOLUME xrx JANUARY, 1940 number 1 



THE BELL SYSTEM 



TECHNICAL JOURNAL 



DEVOTED TO THE SCIENTIFIC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



The Physical Basis of Ferromagnetism — R. M. Bozorth . . 1 



Contact Phenomena in Telephone Switching Circuits 



—A. M. Curtis 40 



Effect of the Quadrature Component in Single Sideband 

 Transmission — H. Nyquist and K, W. Pfteger .... 63 



Low Temperature Coefficient Quartz Crystals — W. P. Mason 74 



A New Standard Volume Indicator and Reference Level 



— H. A. Chinn, D. K. Gannett, and R. M. Morris 94 



Metallic Materials in the Telephone System 



—Earle E. Schumacher and W. C. Ellis 138 



Technical Digest — 



An Interesting Application of Electron Diffraction — 



L. H. Germer and K. H. Storks 152 



Abstracts of Technical Papers 156 



Contributors to this Issue 159 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



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