Transcontinental Telephone Lines * 



By J. J. PILLIOD 



Late in 1937 a large construction project was completed which 

 added 16 telephone circuits to the transcontinental layout, and 

 the work was so planned that 48 additional circuits can be obtained 

 by the addition of equipment but without stringing additional wire. 

 A brief description of some features of this project and the general 

 development of the transcontinental telephone routes since the 

 first one was opened for service in 1915 is given in this article. 

 Although most of the discussion relates to transcontinental lines, 

 the methods described are generally applicable to other similar 

 situations. 



T ESS than twenty-five years ago, it was impossible to talk by tele- 

 -■— ' phone from coast to coast across the United States. Further- 

 more, it was impossible to talk between points separated by any such 

 distance anywhere in the world. By 1915, technological advancement 

 had reached a point such that telephone service could be established 

 across the country, and three telephone circuits had been built which 

 connected San Francisco and the Pacific Coast with points in the East. 

 Four telegraph circuits were also provided by the new wires. An 

 improved loading system and especially the successful development of 

 the vacuum-tube telephone repeater were outstanding factors which 

 made telephone connections of such length possible for the first time in 

 history. 



Open-wire lines played the major role in the early transcontinental 

 telephone circuits. The transmission losses caused by cable were so 

 great that it was avoided whereever possible. The steady improve- 

 ment of telephone repeaters, types of loading for use on cable circuits, 

 and carrier telephone systems for use on open-wire lines made it 

 possible to provide rapidly and economically more telephone circuits 

 across the continent as use of the service grew. In the cross section 



* This paper has been prepared from an address given before the Communications 

 Group of the A. I. E. E., New York Section, March 22, 1938, and published in Elec- 

 trical Engineering for October, 1938. Since the paper was written, three type J 

 12-channel carrier systems have been placed in service on the new line. Two of 

 these systems operate between Oklahoma City and Whitewater, 1200 miles, and 

 the third between Oklahoma City and Albuquerque, N. M. Twelve additional 

 intermediate repeater stations have been constructed. Three of these are located 

 at such remote distances from primary power that experiments are being made in 

 generating by means of wind-mill power plants part of the power required. One 

 such station is shown in Fig. 8. Editor. 



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