398 



ELEMENTARY LESSONS ON [CHAP. xn. 



In Fig. 161 is shown a Morse instrument (an "em- 

 bosser ") M, joined in circuit with a local battery B, and 



Eartli 



Line 



Line Rtttiexy 



Fig. 161. 



a relay. Whenever a current in the line circuit moves 

 the tongue of the relay it closes the local circuit, and 

 causes the Morse to record either a dot or a dash upon 

 the strip of paper. The key K is shown in an enlarged 

 K. 



Fig. 162. 



view in Fig. 162. The line wire is connected with the 

 central pivot A. A spring /"keeps the front end of the 

 key elevated when not in use, so that the line wire is in 



