

VOLUME xn JANUARY, 1933;. ;\ :;; Npi^E^' \, 



u^^vtMv 



THE BELL SYSTEM 



TECHMCAL JOURNAL 



DEVOTED TO THE SCBENTinC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



Pulp Insulation for Telephone Cables — 



H, G. Walker and L. S. Ford 1 



A Recording Transmission Measuring System for 



Telephone Circuit Testing— F. H. Best .... 22 



Probability Theory and Telephone Transmission 



Engineering — Ray S. Hoyt 35 



An Oscillograph for Ten Thousand Cycles — 



A. M. Curtis 76 



Contemporary Advances in Physics, XXV — High- 

 Frequency Phenomena in Gases, Second Part — 



Karl K. Darrow 91 



Abstracts of Technical Papers 119 



Contributors to this Issue 123 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



50c per Copy $1,50 per Year 



