HISTORY AND PROGRESS. 



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minals T. The continuous current circulates in Line L, R, 2, 

 T of switch, over to the right hand, F, D, L B, Earth, &c. 

 An interruption in this circuit caused the relay to work, 



and therefore the Morse M, which directs a current, corre- 

 sponding to each interruption of Line L, in the circuit E, L B, 

 M, 2, G, to T of switch, 2, to Line II. 



A current from Line II. passes through 2 and T of switch 

 to Morse M, G, 1, coils of relay, R', to earth. The Morse M', 



