SOUND. 121 



sound with great facility and distinctness. Two Danish phi- 

 losophers* have shown this by a curious experiment. 



What is it? 



MRS. F. v 



Having stretched a metallic wire 600 feet long, in a hori- 

 zontal direction, they suspended at one end a plate of sono- 

 rous metal; and when this was slightly struck, the auditor, 

 at the other end, with the wire in his teeth, heard, at every 

 stroke, two distinct sounds, one conveyed almost instantly 

 along the wire, and the other transmitted more slowly 

 through the air. By some experiments made in the pipes of 

 Paris, it was ascertained, that sound travels along cast-iron 

 about 10 J times quicker than in air. Glass, iron, and woods 

 are the solids which convey it with the greatest velocity. | 

 There are several other curious points connected with sounds, 

 such as ventriloquism, &c., which I must leave for the 

 present. 



FREDERICK. 



Do ventriloquists really speak from their stomachs] 



, MRS. F. 



No; I believe it is now generally agreed that all these 

 sounds are practised in the throat. 



ESTHER. 



In what, then, does the art of ventriloquism consist? 



MRS. F. 



It is founded upon that property of sound, by virtue of 

 which, the human ear is unable to judge with any accuracy 

 of the direction in which sounds reach it. The art, then, 

 consists in the power of imitating sounds, not only in their 

 ordinary character, but as modified by distance, obstruction, 



* Messrs. Herliold and Rafn. f About 18,530 feet a second. 

 11 



