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ANNUAL REPORT SMITHSONIAN INSTITUTION, 1955 



For those who are unfamiliar with an amplifier of this sort, it may 

 suffice to note that, in basic principle, it is not unlike that which forms 

 part of any radio receiving set in order to amplify the speech waves 

 from a minute amount to that which finally radiates from the loud- 

 speaker. In the case of the cable, the amplifiers are designed to be 

 effective over a very wide frequency band so that they have carrying 

 capacity for many voice channels when used with terminal equipment 

 of the proper type. The vacuum tubes involved must necessarily be 

 very special and have lives many times that of conventional tubes. 



In pursuing this problem of amplification in long cable circuits, 

 British engineers later devised amplifiers that are housed in long tank- 

 like structures. These are suitable for relatively shallow water condi- 

 tions and are laid by somewhat different tecliniques. 



In the new transatlantic cable, whose route is shown in figure 1, the 

 major deep-sea portion of about 2,000 miles is equipped with the 

 flexible amplifiers. The shallower section from Newfoundland to 

 Nova Scotia — some 330 miles — is being equipped with tank-type 

 amplifiers having somewhat greater chaimel-carrying capacity. This 

 route is partly overland. 



Figure 1. — Transatlantic cable route. 



In the case of the long deep-sea portion, a separate cable is laid for 

 each direction of transmission. In the shallow-end section a single 

 cable suffices for both directions of transmission. 



The whole transatlantic circuit, from working terminal to working 

 terminal, is a splendid example of the adaptability of modern com- 

 munication practices. For example, from Nova Scotia to New York, 

 where most of the circuits will terminate, the circuits are largely over 

 repeatered microwave radio links. 



The cable techniques being used, particularly the deep-sea portion, 

 have previously had a tryout in other installations. No apprehension 



