The Bell System Technical Journal 



April, 1930 



Developments in Communication Materials^ 



By WILLIAM FONDILLER 



The subject of engineering materials is one of increasing importance, as is 

 evidenced by the expenditure of over a half bilhon dollars annually in new 

 construction by the Bell System. This has led to the concentration of the 

 research and engineering work on materials in a group devoted particularly 

 to this field of activity. Studies of the chemical and physical properties of 

 materials must be combined by the materials engineer with a knowledge of 

 the operating requirements of telephone apparatus. 



The paper covers broadly the materials used in communication engineer- 

 ing and gives instances in which the needs of the telephone plant imposed 

 requirements which were not satisfied by commercially available materials. 

 Some of the instances cited are phenol fiber having improved resistance to 

 arcing for use in sequence switches; a composite molded plastic for use in 

 terminal strips; textile materials for central office wiring treated to improve 

 their electrical insulating quality and non-ferrous metals of more uniform 



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CORRECTION SLIP FOR ISSUE OF JANUARY, 1930 



of the signal, sound or scene to distant points, or their recording. 



Up to about ten years ago the average manufacturer left to his 

 designing engineer the problem of selecting and testing the materials 

 which were to be embodied in a design, and he in turn was dependent 

 on the manufacturers of raw materials as to the variety and quality 

 of the materials available. Without depreciating the ability or ini- 

 tiative of manufacturers of engineering materials, it will be evident that 

 the special needs of a particular industry would, in general, not be as 

 fully appreciated by an outside manufacturer as by an engineer working 



1 Presented before A. I. E. E. on November 13, 1929. 



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