122 SOUND. 



and other causes, and also, in the power of executing these 

 imitations by muscular exertions which cannot be seen by 

 the spectators. These sounds, then, are produced by the 

 muscles of the throat, assisted by the action of the tongue 

 upon the palate, the teeth, and the inside of the lips all of 

 them being movements perfectly compatible with the abso- 

 lute expression of silence in the countenance, and which may 

 be performed without the movement of the lips themselves. 



But, how does the ventriloquist contrive to give the voice 

 the effect of proceeding from the direction he requires] 



MRS. F. 



If you observe a ventriloquist, you will perceive that he 

 always manages to place himself in the same direction as 

 that in which he wishes the sound to come from. If it be a 

 watchman in the street, that he attempts to represent, he will 

 station himself at the window whence the sound of the real 

 watchman would have entered; or, if he pretends to make a 

 child sing, he will place his head as near as possible to the 

 child's chest, in order to assimilate more closely the real and 

 fictitious direction of the sound. 



ESTHER. 



Then were he, in the first case, to place himself at a win- 

 dow on the opposite side of the room, or, in the other, to 

 sing six or eight feet from the child, he would soon be de- 

 tected. 



MRS. F. 



Exactly so. It is curious to find how acutely sensible is 

 the human ear. Mons. Savart, who has been engaged in ex- 

 periments on its sensibility, has ascertained that this organ 

 is capable of appreciating sounds which arise from about 

 42,000 vibrations in a second; and, consequently, that we can 

 hear a sound which lasts only the 24,000th part of a second. 



FREDERICK. 



Talking of sound, aunt, I have heard that the famous ear 



