NATURAL THEOLOGY. 69 



the labyrinth, from its being so winding and full of 

 passages. There are some other little internal cavi- 

 ties and passages ; one especially leading into the 

 main barrel with a membrane over it, called the fo- 

 ramen rotundum, or round opening ; another, called 

 the Eustachian tube. This is about the whole of the 

 machinery. 



B. There seems to be an abundance of it, but 

 rather complicated and obscure. 



A.. The waves of the air, and what is called 

 sound, is attributed to a certain peculiar motion in 

 the air, resembling waves, produced by the sounding 

 body, are supposed to enter the ear and strike upon 

 the principal drum head, or membrane of the tympa- 

 num, like a drum-stick, and to be communicated, by 

 means of the little bones and the air on the inside to 

 the other drum heads ; these, in their turn, are pre- 

 sumed to operate upon the fluid contained in the bar- 

 rels they cover, so as to affect the delicate filaments 

 of the nerves which float about in this fluid and 

 thereby produce the sensation of hearing. It is 

 one continued transmission through a complicated 

 chain of conductors most mechanically fitted up for 

 the purpose. The sound is also supposed to be car- 

 ried to the nerve, in some degree, through the solid 

 walls of the ear ; just, as in a stick of timber, we 

 can hear the slightest tap upon one end, by holding 

 our ear to the other. 



B. The little bones seem to be the most curious 

 part of the contrivance. 



