12 



THE POPULAR SCIENCE MONTHLY. 



intensity and quality as well as pitch of sound by means of an instru- 

 ment in which the strength of the current could be varied in exact ac- 

 cordance with the tone to be transmitted, and was thus enabled to 



i^ 



Fio. 1. 



reproduce any number of tones simultaneously without losing their 

 specific character a thing plainly impossible with the Reis instru- 

 ment. The device used is shown in Fig. 2. T\ is a mouthpiece into 

 which the person transmitting sounds speaks. Di is a tense thin dia- 

 phragm connected with the line joining the two stations. To the cen- 

 ter of the diaphragm is fastened one end of a metal rod N, whose 

 other end dips into a jar J containing acidulated water. A metal plug 



