84-4 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1952 



Fig. 10 — Microwave radio relay tower at Cotoctin Mountain, Marj-land, on a 

 New York-Washington radio route. There are 300 message circuits in service with 

 more planned. 



on the type of carrier system (Fig. 8) . Coaxial cable transmission systems 

 currently provide up to 600 telephone channels per pair of coaxials 

 (Fig. 9). A new coaxial system, under development, is expected to pro- 

 duce about 1,800 telephone channels per pair of coaxials. 



Most of the applications of radio for toll telephone service now contem- 

 plated, involve the use of pomt-to-pomt microwave systems. By employ- 



