Abstracts of Bell System Technical Papers Not 

 Appearing in this Journal 



A Photo-electric Process of Halftone Negative Making Applicable over 

 Telephone Lines} H. E. Ives. The commercial process of making 

 halftone engravings breaks the picture up into a large number of dots 

 by means of a screen. Unless special intermediate processes are 

 adopted this does not reproduce the tones correctly because the size 

 of the dots is not directly proportional to the light intensity. This 

 paper describes an adaptation of the photo-electric system of picture 

 transmission, as an alternative for use of screen, which produces 

 individual dots more accurately proportional in size to the light 

 intensity. 



The method proposed thus affords a means of improving quality in 

 halftone engraving by using an outfit similar to the picture transmitting 

 and receiving outfit. Used in connection with the commercial picture 

 transmission service, it can provide pictures with an accurate tone 

 structure during the transmission process so that the resulting copy 

 is ready for the engraver without the use of any screen process. Full 

 details of several arrangements of the apparatus are given together 

 with engravings produced by the photo-electric method. 



The picture transmission system as used transmits the picture in 

 the form of a continuous strip of varying intensity. By the intro- 

 duction of a synchronized sectored disc this strip is made discontinuous, 

 forming the dots for the halftone process. 



Advance Planning of the Telephone Toll Plant} J. N. Chamberlain. 

 A general review of the commercial studies which precede the design 

 of telephone toll plant is given together with some specific data con- 

 cerning the toll line conditions in the northern California area of the 

 Pacific Telephone and Telegraph Company. Attention is called to the 

 special conditions requiring a large amount of submarine cable plant 

 resulting from the peninsular location of San Francisco. The Pacific 

 Company has plans for about 1,000 miles of toll cable network in its 

 present program which it expects to install at the rate of 100 miles a 

 year. The article places special emphasis on the commercial factors 

 governing the choice between cable and open wire construction for 

 future extensions of the toll plant. 



1 Opt. Soc. Amer. Jl., Vol. 15, p. 96, August, 1927. 



2 Jl. Am. Inst. Kl. Engrs., Vol. 46, ]). 994, October, 1927. 



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