THE BELL SYSTEM 



TECHNICAL JOURNAL 



VOLUME XVIII, 1939 



Table of Contents 

 January, 1939 



Electrostatic Electron-Optics — Frank Gray 1 



Equivalent Modulator Circuits — E. Peterson and L. W. Hussey . . 32 

 An Improved Three-Channel Carrier Telephone System — 



J. T. O'Leary, E. C. Blessing and J. W. Beyer 49 

 Crossbar Dial Telephone Switching System — 



F. J. Scudder and J. N. Reynolds 76 

 A Twelve-Channel Carrier Telephone System for Open-Wire Lines 



—B. W. Kendall and H. A. Affel 119 

 Recent Developments in the Measurement of Telegraph Trans- 

 mission — R. B. Shanck, F. A. Cowan and S. I. Cory 143 



Contemporary Advances in Physics, XXXII. Particles of the 



Cosmic Rays — Karl K. Darrow 190 



Hurricane and Flood — September 1938 — W. H. Harrison 218 



A Terrain Clearance Indicator — 



Lloyd Espenschied and R. C. Newhouse 222 

 Transcontinental Telephone Lines — /. /. Pilliod 235 



April, 1939 



Some Ceramic Manufacturing Developments of the Western 



Electric Company — A. G. Johnson and L. I. Shaw 255 



The Production of Ultra-High-Frequency Oscillations by Means 



of Diodes — F. B. Llewellyn and A . E. Bowen 280 



A Representation of the Sunspot Cycle — C. N. Anderson 292 



The Number of Impedances of an n Terminal Network — 



John Rior dan 300 

 Copper Oxide Modulators in Carrier Telephone Systems — 



R. S. Caruthers 315 

 3 



