Soande 



ELECTRICAL APPLIANCES AND MACHINES 265 



increased force because of the local battery which operates 



the sounder. The armature of the sounder clicks when 



it is drawn down by 



the magnet, and also 



when it is drawn 



back up by a strong 1 ~J-o J L 



W Re/ay Xe/: 



spring. The time 

 elapsing between two 

 successive clicks in- 

 dicates to the oper- 

 ator whether it is a 

 dot or a dash. 



The circuit of a telegraph system is kept closed when 

 not in use. When the operator in Pittsburgh wishes to 

 send a message to Chicago, he opens the switch and 



A TELEGRAPH SYSTEM 



AMATEUR WIRELESS RECEIVING AND SENDING APPARATUS 



operates the key which makes and breaks the circuit as 

 the dots and dashes are made. The sounder in Chicago 



