A SUBMARINE TELEPHONE CABLE WITH SUBMERGED REPEATERS 



73 



ments — condensers, resistances, and coils — especially where they are subject 

 to long continued application of electrical potentials, as in the case of power 

 separation filters. The factors that determine the life and performance of 

 these elements are not completely under control. It was felt, however, that 

 the best assurance on dependability could be obtained by careful, conserva- 

 tive design and by manufacturing and assembling the elements into repeaters 

 under the best possible conditions of cleanliness. An air conditioned space 

 was provided for this purpose at the Murray Hill Laboratory. In addition to 

 cleaning the air in this space, precautions were taken against the entrance of 

 dirt by other means, for example, on the clothing or persons of operators. 



Fig. 5 — Assembly of the repeater. 



The humidity of the air was carefully controlled to prevent contamination 

 from perspiration during handling of the parts. Manufacture was carried out 

 by selected workmen, and the product was inspected at various stages by 

 engineers. A view of one of the operations is given in Fig. 5. 



Field Trials 



Simulated laying tests in the laboratory covered a period of several years. 

 Special pains had been taken to include as far as possible all aspects of the 

 laying operation, even those which were judged to be free of hazard to the 

 repeater. Tests were also made to determine the effect, if any, of the laying 

 operation upon the electrical transmission characteristics of the cable. Like- 

 wise, comprehensive electrical tests had been made to insure that no unex- 



