NFJV YORK-CUICACO CABLE 



77 



can be accomplished 1)\' tlie use of telephone repeaters connected to 

 the loaded conductors. 



Telephone repeaters have been developed to a high state of per- 

 fection and are completely described in a paper presented by Messrs. 

 Bancroft Gherardi and Frank B. Jewett at a joint meeting of the 

 A. I. E. E. and the Institute of Radio Engineers in New York, October 

 1, 1919. Briefly, the purpose of a telephone repeater is to receive 

 small telephone currents, amplify them and send them on, preserving 



Fig. 20 — Vacuum Tube 



all the while the original wave shape. Therefore, if one or more tele- 

 phone repeaters are properly inserted in circuits adapted to their use, 

 the range of satisfactory transmission can be greatly extended. As 

 many hundreds of vacuum-tube repeaters are in operation on the 

 Philadelphia-Pittsburgh cable and connected cables, and as a great 

 many more are planned for future installation, we will briefly consider 

 the elementary features of some of the types of repeaters used. 



Fig. 20 shows the structure of the vacuum tube which is an essential 



