ADVANCES IN TELEGRAPHY 327 



In actual practice messages are not ordinarily sent long 

 distances over a direct line, but are automatically transferred 

 to new lines at definite points. For example, a message from 

 New York to Chicago does not travel along an uninterrupted 

 path, but is automatically transferred at some point, such as 

 Lancaster, to a second line which carries it on to Pittsburgh, 

 where it is again transferred to a third line which takes it 

 farther on to its destination. 



