544 BELL SYSTEM TECHNICAL JOURNAL 



nected in tandem giving an overall length of 7500 miles (12,000 

 kilometers) of circuit. Conversations over this 7500-mile (12,000- 

 kilometer) circuit were very satisfactory. In fact, the transmission 

 quality was not greatly impaired even when a 15,000-mile (24,000- 

 kilometer) length of one-way circuit was established by connecting all 

 of the links in tandem. 



While the development of this carrier system is far from completion 

 and it is not clear at the present time how far it can be applied to 

 other than heavy traffic routes, it is certain that wherever this form 

 of construction is justified, distance no longer remains as a limiting 

 factor. 



In the fifty years since the first International Electrical Congress 

 at Paris, the new art of telephone communication has passed through 

 many stages of development and during the past thirty years a new 

 att, making possible communication in cable over long distance, has 

 been born and brought to maturity. This has been made possible by 

 a number of important and fundamental developments such as 

 loading, quadded cable and telephone repeaters. While the develop- 

 ment has been rapid, particularly during the past twenty years, it is 

 not too much to expect that the next twenty or thirty years will 

 witness an even greater and more rapid technical development and 

 expansion in the use of long distance toll cables in all parts of the 

 world, associated with a continued increase in the service rendered to 

 mankind by long distance telephone communication. 



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