A SUBMARINE TELEPHONE CABLE WITH SUBMERGED REPEATERS 87 



of barrels and winch line and paid out cable to the point of final splice, 

 which in this case was about four miles from Sand Key. The end of No. 6 at 

 Sand Key was then picked up, a repeater spliced to it and to the end of the 

 cable in the tank, and the latter was paid out to the point of final splice. 

 Within a short time after completing this splice, insulation measurements 

 had been completed on the two cables, the power supply was connected in to 

 activate the repeaters, and conversation over the cable system took place. 



Careful attention was given to the amount of slack paid out, that is the 

 excess of cable length over the actual distance traversed. This latter distance 

 is usually determined by observing the length of a taut wire paid out con- 

 tinuously during the laying. In the absence of taut wire gear other methods 

 had to be devised. Observations on buoys by radar and range finder provided 

 almost continuous information regarding the position of the ship and gave 

 satisfactory information on slack. The conditions for cable laying between 

 Key West and Havana are far from good. The Gulf Stream is swift and er- 

 ratic. The velocity of the current at any particular point as indicated by the 

 stream at the buoys was found to vary considerably over a fairly short period 

 of time. As an indication of the degree of precision obtained by careful navi- 

 gation of the ship, the final results show that in each of the cables the speci- 

 fied length was missed by only .2 n.m., which is quite an unusual achieve- 

 ment. 



Acknowledgment is made to the Western Union Telegraph Company, the 

 owners of the LORD KELVIN, for their cooperation in providing the special 

 equipment for the ship and to the Captain of the LORD KELVIN, his staff 

 and crew, for the very satisfactory performance of the laying operation. 



Since the installation of the new system, it has been subjected to compre- 

 hensive tests involving measurement of noise and intermodulation between 

 channels as well as precise measurements at numerous frequencies of net loss 

 of the repeatered cables at intervals of time. The system has proved to be 

 very stable and has met the requirements laid down for it. This was as ex- 

 pected. Nothing unfavorable to the submerged repeater has made itself felt; 

 but, in accordance with conservative submarine cable tradition, its perform- 

 ance will be critically observed over a period of time. 



Activity in the development of the repeatered cable and the conduct of the 

 Key W^est-Havana project centered in a small group of Bell Telephone Lab- 

 oratories' engineers specializing in submarine cable work and drawing on 

 the advice and help of other groups of various backgrounds. At times, espe- 

 cially when troubles were encountered, the contributions of these groups were 

 of tremendous importance and considerable in extent. The writer, as project 

 engineer, takes this opportunity of acknowledging the assistance of the nu- 

 merous individuals involved in the success of the undertaking. 



