HISTORY AND PROGRESS. 



19 



passed between the gold points corresponding to the ter- 

 minals touched by the poles, and returned through the other 

 line wire to the terminal of the other pole of the pile. 



In doing this, bubbles of hydrogen appeared at the gold 

 point in communication with the positive pole, and bubbles of 

 oxygen at the other one. Thus two signals were given simul- 

 taneously, to which that of the hydrogen took precedence. 

 When it was desired to indicate only one letter, the positive 

 pole of the battery was brought in connection with zero and 

 the negative with the letter to be transmitted. The con- 



ABODE FGHIJKLMNOPQRS TUVVVYZ 1234567 89 OH 



ABCDEFGHIJKLMNOPQRSTUVW1Z12 3456 78 90 



Fig. 7. 



nection wires were well insulated, and, at a little distance 

 from the transmitting terminals at one end, and from the 

 voltameters at the other, were bound up in the form of a 

 cable. Sommering proposed to call the attention of the 

 receiving station by liberating an alarm by means of accu- 

 mulated gas. 



Fig. 7, a copy of that given by Sommering in his descrip- 



c2 



