DEVELOPMENT OF THE TELEGRAPH 



Salva pointed out that if double wires were laid from 

 the city of Barcelona to Mataro, and a man at Mataro 

 should hold the ends, he could be given a shock from a 

 Leyden jar from the Barcelona end, and messages pre- 

 viously determined communicated to him. But such 

 simple signaling would not suffice, as any telegraph to be 

 practical must be able to send communications of every 

 kind, and this, Salva thought, could be done with no 

 great difficulty. 



With eighteen letters every word in the language may 

 be expressed. Thus by having eighteen or twenty 

 wires, and a corresponding number of Leyden jars, 

 with a man holding each jar and representing a letter of 

 the alphabet, it would be possible to communicate 

 definite messages to a distant city. This, of course, 

 could be simplified, and Salva suggested that by reduc- 

 ing the number of men to six or even less, each man 

 interpreting three or more signals as certain letters, 

 definite messages could be sent. 



But as even this number of wires, no matter how high 

 they might be mounted above the ground, would be 

 likely to be injured, Salva suggested insulating them 

 and putting them into a single cable. He even went 

 further than this and suggested the submarine use of 

 the cable probably the first suggestion of this kind re- 

 corded. In this suggestion the double wire was to be dis- 

 pensed with, the water being used for the return circuit. 



Shortly after the time of Salva's telegraph a French- 

 man by the name of Alexandre seems to have perfected a 

 practical telegraph which worked on the principle of an 

 indicator that pointed to the letters marked on a dial 



[9] 



