HISTORY AND PROGRESS. 



97 



when the stations are corresponding, and when both have 

 done, at a given signal, he re-arranges his commutator for 

 regular work. This signal is given by both stations simul- 



G. 



taneously, and consists in pressing down their keys for the 

 space of one minute, by which the needles of the galvano- 

 scopes are deflected steadily in one direction for that length 

 of time. 



In the second position, by which the intermediate station 

 participates in the messages transmitted by the 

 distant stations, and which are, for the most part, 

 official instructions, time, or information for the 

 employes, contact pegs are put into holes 1 and 6. 

 A current then arriving from the same side will 

 traverse G L , L, 1, R , 2 (coils of relay), 1, R,,, 6, L, 

 G 2 , to the other line. The relay then performs its 

 functions of closing the local circuit and setting the 

 recording instrument in motion. 



Position No. 3 is attained by two different arrangements 

 of the contact pegs, according as the one or the other of the 



H 



61t 



