Fig. 86. FROMENT'S WRITING TELEGRAPH. 



THE ELECTRIC TELEGRAPH. 



CHAPTEE X. 



212. Operation of Bain's telegraph. 213. Its commutator. 214. Its 

 extraordinary speed of transmission. 215. Obstructions to its 

 practical application. 216. Its prospects. 217. Autograph telegraph. 

 218. House's printing telegraph. 219. Its operation. 220. 

 Henley's magnetic telegraph. 221. Brett's printing telegraph. 

 222. Celerity of telegraphic communication. 223. Circumstances 

 which affect it. 224. Comparative ability of telegraphists. 225 

 Each telegraphist known by his manner of transmitting. 226. Easier 

 to transmit than to receive. 227. Pauses in transmission. 228. 

 Rate of transmission with double needle instruments worked by voltaic 

 current. 229. Rate with magneto-electric current. 



212. Now, let us suppose that the galvanic circuit is completed 

 in the manner customary with the electric telegraph, that is to 

 say, the wire which terminates at the point of the electro-chemical 

 pen is carried from the station of arrival to the station of de- 

 parture, where it is connected with the galvanic battery, and 

 the returning current is formed in the usual way by the earth 

 itself. When the communication between the wire and the gal- 

 vanic battery at the station of departure is established, the 

 current will pass through the wire, will be transmitted from the 

 point of the electro-chemical pen to the moistened paper, and will, 



LARDNER'S MUSEUM OP SCIENCE. K 49 



No. 45. 



