THE TELEPHONE AND TELEGRAPH 



215 



that Mr. Smith is calling, and connects herself with his line 

 by inserting one of a pair of plugs in the answering jack. 



The top of operator A's switchboard contains a hole for 

 every number on the Audubon exchange, and an additional 



FIG. 04. Operating Room in a Small City Exchange. 



one for a trunk line. (The operation of the trunk line will 

 be explained later.) 



Should Mr. Smith be calling Mr. Jones, whose line is also 

 on the Audubon exchange, the operator can make the con- 

 nection directly by inserting the other plug of trie pair at 



