Page:Popular Science Monthly Volume 17.djvu/22

12 intensity and quality as well as pitch of sound by means of an instrument in which the strength of the current could be varied in exact accordance with the tone to be transmitted, and was thus enabled to



reproduce any number of tones simultaneously without losing their specific character—a thing plainly impossible with the Reis instrument. The device used is shown in Fig. 2. T1 is a mouthpiece into which the person transmitting sounds speaks. D1 is a tense thin diaphragm connected with the line joining the two stations. To the center 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