CONQUEST OF DISTAXCE BY WIRE TELEPHONY 365 



when long switching trunks were involved at the two ends. Consequently, 

 as soon as the subsequent developments in telephone repeaters would per- 

 mit, experimental repeaters were j)ut into use on the New York-Denver 

 connections. 



The Denver line was not a through or terminal circuit, ready for use on 

 call. It was built up when needed, with switches at Morrell Park (Chicago) 

 and Omaha. When it became necessary to use side circuit portions as sub- 

 stitutes for the phantom circuit portions, the over-all transmission was 

 several db worse than w^hen the phantoms were used. This was partly a 

 result of the higher attenuation of the side circuits, and partly because one 

 of the side circuits was arranged for telephone connections and leased wire 

 telegraph at several intermediate points between Omaha and Denver. 



There was a heavy use of grounded d-c telegraph service on the composited 

 line wires. At times, serious impairment to the telephone transmission was 

 caused by non-linear distortion resulting from transient magnetization of the 

 loading coil cores by the superposed telegraph currents. This effect became 

 known as "Morse flutter" and later on as "telegraph flutter." It had 

 previously been noticed on shorter loaded lines, but as the composited 

 loaded lines became longer and longer, the flutter interference became more 

 and more serious. Subsequent developments, first used on the transcon- 

 tinental line, resulted in a considerable reduction of telegraph flutter per 

 unit length of line, but there always was an appreciable amount on long 

 loaded lines when they were used for composite telegraph circuits. 



Boston-Washington Loaded Duplex Cable Project 



As previously indicated, a main purpose of this project as planned in 

 1909-1910 was to provide storm-proof communications between the prin- 

 cipal eastern cities. This project is historically significant as being the first 

 long-distance cable system to use quadded cable and phantom group load- 

 ing. It was also the longest telephone cable system ever designed for use 

 without repeaters. Fortunateh", a satisfactory t^-pe of telephone repeater 

 became available for commercial use before the project was completed, and 

 its value w^as thereby greatly enhanced. 



General: The over-all length, Boston to Washington, was about 455 

 miles, with New York close to the half-way point. Underground conduit 

 already existed for about half of the total distance — Boston to Providence, 

 and New Haven to New York to Philadelphia to Wilmington. Heavy- 

 loaded, non-quadded, 16, or 14, or 13-gauge cables were already in com- 

 mercial use in different parts of the route but, in general, since they had been 

 designed for shorter distances, they were not sufficiently eflicient to be used 

 in tandem connections with new cable as portions of Boston-New York or 

 New York-Washington all-cable facilities without also using telephone 



