.V/A' WILLIAM SIEMENS, F.K.S. 13 



electro-motive force ; but nature had imposed its limits in this 

 direction, for if the force became excessive, the discharge would 

 no longer pass through the length of the cable, and back through 

 the earth, but would cross the insulating medium in the form of 

 a spark, and disable the entire cable. It had also been proposed 

 to send a considerable number of waves of positive and negative 

 electricity simultaneously through the cable, but Mr. Siemens 

 asserted, that the number of waves that could in that way pass 

 through long cables, without destroying each other, was limited 

 to three or four. He did not believe that it would be possible to 

 send through the projected Atlantic cable, more than one word 

 per minute. 



Mr. Siemens had carefully investigated this subject, and had, he 

 thought, discovered means of accelerating the passage of an elec- 

 tric wave through a cable to twice its natural velocity, by simply 

 returning the current through a second insulated wire within the 

 cable, instead of through the earth. The two wires being simul- 

 taneously charged, the one with positive and the other with 

 negative electricity, completely neutralized the electric charge of 

 the metallic covering of the wire. Other disturbing causes, such 

 as the magnetization of the surrounding iron covering, which 

 exercised a very considerable retarding effect upon the electric 

 wave, would also be removed. The positive and negative waves 

 in the two enclosed wires, would likewise mutually accelerate each 

 other by voltaic induction. In the experiments of Mr. White- 

 house, the line wires had accidentally been under precisely similar 

 circumstances to those provided by Mr. Siemens ; but, judging 

 from the projected Atlantic cable, it did not appear that the 

 advantages obtained had been appreciated, as otherwise the cable 

 would have been constructed on totally different principles. 



