Masterpieces of Science 



For several years my attention was almost 

 exclusively directed to the production of an in- 

 strument for making and breaking a voltaic 

 circuit with extreme rapidity, to take the place 

 of the transmitting tuning fork used in Helm- 

 holtz's researches. Without going into details, 

 I shall merely say that the great defects of this 

 plan of multiple telegraphy were found to con- 



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Fig. 2 



sist, first, in the fact that the receiving oper- 

 ators were required to possess a good musical ear 

 in order to discriminate the signals; and secondly, 

 that the signals could only pass in one direction 

 along the line (so that two wires would be neces- 

 sary in order to complete communication in both 

 directions). The first objection was got over 

 by employing the device which I term a "vibra- 

 tory circuit breaker, ' ' whereby musical signals 

 can be automatically recorded. . . . 

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