THE 



POPULAR SCIENCE 

 MONTHLY. 



AUGUST, 1873. 



ELECTRIC TELEGRAPHS. 1 



By Pbof. A. P. DESCHANEL. 



THE discovery that electricity could be transmitted instantaneously 

 to great distances at once suggested the idea of employing it for 

 signalling. Bishop Watson performed several experiments of this 

 kind in the neighborhood of London, the most remarkable being the 

 transmission of the discharge of a Leyden jar through 10,600 feet of 

 wire suspended between wooden poles at Shooter's Hill. This was in 

 1747. A plan for an alphabetical telegraph to be worked by electricity 

 is minutely described in the Scot's Magazine for 1753, but appears to 

 have been never experimentally realized. Lesage, in 1774, erected at 

 Geneva a telegraph-line, consisting of twenty-four wh*es connected 

 with the same number of pith-ball electroscopes, each representing a 

 letter. Reusser, in Germany, proposed, in the same year, to replace 

 the electroscopes by spangled panes exhibiting the letters themselves. 

 The difficulty of managing frictional electricity was, however, suffi- 

 cient to prevent these and other schemes founded on its employment 

 from yielding any useful results. Volta's discoveries, by supplying 

 electricity of a kind more easily retained on the conducting wires, 

 afforded much greater facilities for transmitting signals to a distance. 

 Several suggestions were made for receiving-apparatus to exhibit 

 the effects of the currents transmitted from a voltaic battery. Som- 

 mering, of Munich, in 1811, proposed a telegraph, in which the signals 

 were given by the decomposition of water in thirty-five vessels, each 

 connected with a separate telegraph-wire. Ampere, in 1820, proposed 

 to utilize CErsted's discovery by employing twenty-four needles, to be 

 deflected by currents sent tln*ough the same number of wires ; and 

 Baron Schilling exhibited, in Russia, in 1832, a telegraphic model, in 



1 Abridged from Deschanel's "Natural Philosophy," Part III. : " Electricity and Mag- 

 netism." 



tol. in. 20 



