TELETYPEWRITER EXCHANGE SYSTEM 



527 



has been arranged to operate in conjunction willi the telegraph line 

 facilities. The station loop is a pair of wires such as those used for 

 telephone service. Each inter-toll trunk consists of one or more 

 sections of the same standard types of carrier, metallic, or grounded 

 telegraph line systems that are employed in private line telegraph 

 service. The signaling and supervisory apparatus is all contained in 

 the TWX switchboard equipments. 



Fig. 15 — A built-up connection such as would be used if all direct New York-San 

 Francisco trunks were busy. 



In the example illustrated the New York operator, being the 

 outward operator, supervises the call and times the ticket. The 

 following traffic table shows the important steps taken in setting up 

 and^taking down this connection : 



1 . The New York subscriber calls: Subscriber closes loop and starts teletypewriter 

 by operating switch. Subscriber line lamps light in the New York switchboard. 



2. A New York operator answers with the cord typing key {similar in function to 

 the talking key in the telephone cord circuit) operated: The line lamps are extinguished. 

 The operator and subscriber communicate. 



