TRANSATLANTIC TELEPHONE CABLE — AFFEL 295 



the high frequencies of the speech channels find free access to their 

 respective terminal equipments. 



The repeatered cable on the Clarenville-Oban section will require 

 initially a total voltage of about 3,700 volts, increasing with later years 

 perhaps to about 4,450 volts, or even up to about 4,700 volts if it is 

 necessary to introduce additional repeaters after repairs. 



Since these voltages are divided between the two terminals, the 

 maximum voltage on the cable is only half the above figures. For the 

 repeaters on the Clarenville-Sydney Mines section, the necessary total 

 driving voltage will be only about 2,300 volts and, if necessary, it will 

 be possible to feed this from one end only since the cable and other 

 circuit elements will withstand this voltage. 



There are some differences in the makeup of the constant-current 

 generators used on the two sections but these are incident to the par- 

 ticular problems involved and not generically unportant. 



Every effort will be made to insure continuity of tlie direct-current 

 power supply to each cable. In order to assist this, the alternating 

 current supplied to each constant-circuit power-feed miit will be de- 

 rived via alternating-current — direct-current — alternating-current 

 machines. These machines will normally be driven from commercial 

 power-supply means. In the event of power-supply failure, a storage 

 battery continues to drive the direct-current machine. If the failure 

 is of long duration, d,iesel engines will be started up. 



CABLE-LAYING ARRANGEMENTS 



All the cable is being laid by the cable ship Monarch. This ship, 

 which was built for the British Post Office in 1945, has a gross tonnage 

 of some 8,000 and, with full oil bunkers, can carry between 5,000 and 

 6,000 tons of cable.5 



The Monarch is the only ship afloat capable of laying the whole of 

 the deep-water part (about 1,600 nautical miles) of each cable between 

 Newfoundland and Scotland in one operation. It is obviously desir- 

 able to avoid any sequence of operations which will make it necessary 

 to pick up a cable end and make a splice in deep water. Such opera- 

 tions will have to be carried out if repairs are necessary after the cable 

 has been laid, but inevitably at some risk of the cable's kinking. All 

 repeaters are joined into the cable before it is loaded into the ship. 



A period of 12 days during which continuously good weather condi- 

 tions may be anticipated is necessary in order to carry out the main 

 operation without undue hazard to the repeatered cable. In the North 

 Atlantic such conditions are unlikely except during the period mid- 

 May to mid-September, and it has not been practical to lay both the 



' The tons referred to here and elsewhere in the paper are long tons of 2,240 

 pounds. 



370930 — 56 20 



