HISTORY AND PROGRESS. 



143 



the circuit breaker. Behind the galvanoscopes B B are fourteen 

 terminal screws, to which the wires leading from the apparatus 



Fig. 80. 



are brought, their arrangement being as follows : L is the 

 line wire, E the earth wire, c copper pole, and z zinc-pole of 

 battery. The local circuit, indicated by dotted lines, shows 

 the terminals between which the local battery is connected. 



