THE BELL SYSTEM 



TECHNICAL JOURNAL 



VOLUME XXX, 195 1 



Table of Contents 



January 1951 



The Type N-1 Carrier Telephone System: Objectives and Transmis- 

 sion Features — R. S. Caruthers 1 



Television by Pulse Code Modulation — W. M. Goodall ?>2t 



Prediction and Entropy of Printed English — C. E. Shannon 50 



A Submarine Telephone Cable with Submerged Repeaters — J. J. 



Gilbert 65 



Theory of the Negative Impedance Converter — J. L. Merrill 88 



The Ring Armature Telephone Receiver — E. E. Mott and R. C. Miner. . 1 10 



Internal Temperatures of Relay Windings — R. L. Peek 141 



The Evolution of Inductive Loading for Bell System Telephone 



Facilities — T. Shaw 149 



April i951 



The Seventy-fifth Anniversary of the Telephone 213 



Seventy-five Years of the Telephone: An Evolution in Technology — 



W. E. Martin 215 



An Improved Telephone Set — A . H. Inglis and W. L. Tuffnell 239 



Pyrolytic Film Resistors: Carbon and Borocarbon — R. O. Grisdale, A. 



C. Pfister, and W . van Roosbroeck 271 



The Potential Analogue Method of Network Synthesis — Sidney 



Darlington 315 



Zero Temperature Coefficient Quartz Crystals for Very High Tem- 

 peratures — W. P. Mason 366 



Duality as a Guide in Transitor Circuit Design — R. L. Wallace, Jr. 



and G. Raisbeck 381 



Some Design Features of the N-1 Carrier Telephone System — W. E. 



Kahl and L. Pedersen 418 



The Evolution of Inductive Loading for Bell System Telephone Facili- 

 ties (Continued) — Thomas Shaw 447 



July 1951 



Reduction of Skin Effect Losses by the Use of Laminated Conductors 



—A. M. Clogston 491 



111 



