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THE POPULAR SCIENCE MONTHLY. 



The transmitter in Fig. 1 consists of a conical tube, a, closed at 

 the smaller end by a collodion membrane, o, on the center of which 

 rests the end of a very light bent lever, c d, supported at e, and thrown 





Pig. 1. 



forward into contact with the spring g by the delicate spring n. The 

 spring g is adjustable by the screw h. The electric connections will be 

 easily traced. In the description, g is explicitly described as a spring / 

 and the essential feature to be observed in this type is the current 



