5 68 



HISTORY OF SCIENCE. 



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u BII BIT 



B3 



FIG. 284. 



is generated by the machine under conditions less favourable than 

 those which the voltaic pile presents. In 1809 Sommering invented 

 the first telegraph in which a voltaic current was employed. His 

 apparatus displayed much ingenuity ; but, although it was shown in 

 operation, and from time to time short experimental lengths were set up, 

 it never came into actual use. Sommering's apparatus is represented in 

 Fig. 284, where A is the voltaic pile. B, is a frame in which are fixed 

 twenty-four short metal rods, each marked with a letter of the alphabet. 

 Each rod is attached to a wire, and has a small hole drilled vertically 

 through it. Part of this frame is shown on a larger scale in B 2 , and in 

 plan in B 3 . The twenty-four wires, which are insulated from each 

 other by a non-conducting covering, are twisted into a single cable, 

 E E, which reaches to the station to which the messages are to be sent. 

 Here the wires separate, and each passes through the bottom of a 

 trough with glass sides, where it is marked with the corresponding letter 

 of the alphabet. This arrangement is shown at Ci, and part of it on a 



