8 THE ELECTRIC TELEGRAPH. 



length of wire that has been tried hitherto, yet, as that has never 

 exceeded some thirty or forty yards, it may be reasonably supposed 

 that in a far greater length it would be remarkably diminished, and 

 probably would be entirely drained off in a few miles by the sur- 

 rounding air. To prevent the objection, and save longer argument, 

 lay over the wires from one end to the other with a thin coat of 

 jewellers' cement. This may be done for a trifle of additional 

 expense ; and as it is an electric per se, will effectually secure any 

 part of the fire from mixing with the atmosphere. 



I am, &c., 



" C. M." 



This is one of the most interesting documents to be found 

 in the whole history of Telegraphy. The writer was, evidently, 

 not acquainted with Watson's experiments, or he would not 

 probably have suggested insulation by "jewellers' cement ; " 

 but the suggestion was an ingenious one. The idea which 

 we find of keeping his lines charged with electricity, and 

 giving the signals by discharging them, as well as that of 

 reading signals by sound of bells, both of which, long years 

 afterwards, were brought, with certain modifications, into 

 practice, deserve to be remembered to his credit. 



12. To Lesage,* however, belongs the honour of having 

 established, in practice, the first telegraph wire for the trans- 

 mission of intelligible signals. His system was almost the 

 realisation of the idea of the Scotchman, " C. M." He erected 

 at Geneva, in 1774, a telegraph line of twenty- four metallic 

 wires, insulated from each other. Each wire was connected 

 at the further end to a separate pith-ball electroscope, and 

 corresponded to one of the letters of the alphahet. In this 

 way any letter could be indicated hy bringing to the end 

 of the wire corresponding to the letter to be sent, a source of 

 static electricity produced by friction, which would imme- 

 diately cause the divergence of the pith balls of that par- 

 ticular electroscope. 



13. The electroscopes used in these experiments consisted 

 of two small pith balls suspended from a common metallic 

 support, by cotton threads or fine wires. It will, without 



* Moigno's " Telegraphic Electrique," p. 59. 



