Masterpieces of Science 



of vibration in the other, for the intensity of the 

 induced current is determined by the amplitude 

 of the inducing vibration, and the amplitude of 

 the vibration at the receiving end depends upon 

 the intensity of the attractive impulses. When 

 we sing into a piano, certain of the strings of the 

 instrument are set in vibration sympathetically 

 by the action of the voice with different degrees 

 of amplitude, and a sound, which is an approxi- 

 mation to the vowel uttered, is produced from the 



Fig. 3 



piano. Theory shows that, had the piano a very 

 much larger number of strings to the octave, the 

 vowel sounds would be perfectly reproduced. 

 My idea of the action of the apparatus, shown 

 in Fig. 3, was this: Utter a sound in the neigh- 

 bourhood of the harp H, and certain of the rods 

 would be thrown into vibration with different 

 amplitudes. At the other end of the circuit the 

 corresponding rods of the harp H would vibrate 

 with their proper relations of force, and the 



