PHYSICS NINETEENTH CENT. SOUND. 



547 



ported on a cylindrical or other grooved surface so that the steel point 

 is always opposite the grooves. When the sounds have been registered 

 on the sheet of tinfoil, they are reproduced by the instrument when 

 the indented sheet is again drawn under the steel point. Phrases in 

 three different languages have been simultaneously spoken into the 

 instrument, and the superimposed sounds have been so reproduced 

 that the words of each language were distinctly recognized. We see, 

 therefore, that the vibrating discs of the telephone and the phonograph 

 can combine different systems of impulses, however numerous and 

 complex, into definite movements, in which all the systems are simul- 

 taneously represented. 



352 



