CONQUEST OF DISTANCE BY WIRE TELEPHONY 389 



pecially on the transcontinental line, such cables were avoided when 

 practicable, and those that could not be avoided were made as short as prac- 

 ticable. In some instances long incidental cables were avoided by locating 

 the repeaters in a test station at the city outskirts — Brushton (Pittsburgh) 

 and Morrell Park (Chicago), for example. 



Several types of treatment were applied to incidental cables that could 

 not be avoided. Short cables havmg capacitances materially less than that 

 of an open-wire loading section were taken into account in the layout of the 

 open-wire loading. This method was also applied to bridle wire at test 

 stations. 



Long cables were provided with a new type of impedance-matching load- 

 ing. The coil inductances and spacings were such that the loaded cable 

 would have about the same nominal impedance and the same cut-off fre- 

 quency as the loaded open-wire circuits, these being the requirements for 

 minimizing the junction reflection effects. This was the first use of im- 

 pedance-matching loading on incidental cables in loaded lines. Previously, 

 it had been the general practice on entrance cables to use some standard 

 weight of toll cable or exchange cable loading, for example on the Boston- 

 Neponset cable described earlier in this story. These former loading prac- 

 tices reduced the cable attenuation and the jimction reflection loss, both 

 being desirable objectives, but resulted in junction impedance irregularities 

 large enough to be objectionable on repeatered circuits. In due time, it 

 was found desirable also to use an extra light-weight impedance-matching 

 loading for incidental cables in non-loaded open-wire lines, when used in 

 conjunction with telephone repeaters. Later on, this need became especially 

 important in lines used for carrier telephone systems, and suitable types of 

 high cut-off, impedance-matching, carrier loading, were developed. 



Line Insulation: Because of the high impedance of the loaded line and 

 its great length, it was particularly important to keep the leakage losses as 

 low as possible. An interesting problem in this connection was the effect 

 of the salt on the line in the vicinity of Great Salt Lake in Utah. The 

 Mountain States Company equipped itself to take care of the situation by 

 using steam from the boiler of an old Stanley steam automobile to clean the 

 insulators, when necessary. 



The First Transcontinental Circuits 



The construction of an entirely new phantom group between Denver and 

 San Francisco began during the summer of 1913 via Rawlings, Salt Lake 

 City, Winnemucca, Sacramento, and Oakland. An interesting account of 

 the construction problems is given in an article, "The Circuits Go Up," 

 by H. H. Nance and R. M. Oram, which is one of a series of articles com- 

 memorating a quarter century of transcontinental service, published in the 



