512 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1954 



Steeneck, W. R.^ 



Nl Carrier Equipment Design, Commiiii. Eng., 13, pp. 26-28, Sept- 

 Oct., 1953. 



Progress in telei)hone apparatus and in radio equipment design seem to 

 follow convei-ging ]iatlis, eacli contril)uting something to the other. Bell 

 Laboratories started in the telejihone field and adopted radio as an accessor}' 

 means of transmission. More recently, radio manufacturers have boiTowed 

 telephone-circuit techniques for remote controls and multiplexing. The Nl 

 equipment, while it looks more like radio than telephone apparatus, is a 

 most interesting example of economy in manufacture, testing, service, and 

 also in cubic contents. And those gains have been achieved, it should be 

 noted, as part of a program to increase reliability and to reduce the dura- 

 tion of outages. 



Tanenbaum, M} and H. B. Briggs.^ 



Optical Properties of Indium Antimonide, Letter to the Editor, Phys. 

 Rev., 91, pp. 1561-1562, Sept. 15, 1953. 



Thaeler, C. S., see A. J. Aikens. 



Tien, P. K} 



Traveling-Wave Tube Helix Impedance, I.R.E., Proc, 41, pp. 1617- 

 1623, Nov., 1953. 



The impedance parameter of a circular helix, from which the gain of a 

 helix-t^-pe traveling wave amplifier is computed, is investigated for a "Tape- 

 Helix" model. Results obtained in this paper indicate that the impedance 

 has a smaller value than for the "Sheath-Helix" model, and is considerably'' 

 reduced at larger values of ka, the ratio of the helix circumference to the 

 free space wavelength. A tape helix surrounded by a dielectiic medium is 

 analyzed. It is shown that tlie results obtained from the theor}- can be used 

 to evaluate the helix impedance for usual tj-pes of travehng wave tubes. 

 The}' have been found to be in agreement with measurements on many 

 tube designs. 



Walker, L. R., see J. R. Pierce. 



Wilkinson, R. I.^ and H. G. Romig.^ 



Random Picture Spacing with Multiple Camera Installations, 8. INI. 

 P.T.E. J., 61, pp. 605-618, Nov., 1953. 



When several high-speed cameras are operated simultaneously, but in- 

 dependently, it is possible that the aggregate of pictures obtained will 



1 Bell Telephone Laboratories, Inc. 



