HEARING. 



421 



1 have endeavoured, in Fig. 390, to exhibit, 

 in one view, the principal parts of this compli- 

 cated organ, as they exist in man, in their rela- 

 tive situations, and of their natural size ; thereby 

 affording a scale by which the real dimensions 

 of those portions, which I shall afterwards have 

 occasion to explain by magnified representations, 

 may be properly appreciated.* 



The Concha, or external ear (c), is formed of 

 an elastic plate of cartilage, covered by inte- 

 gument, and presenting various elevations and 

 depressions, which form a series of parabolic 

 curves ; apparently for the purpose of collecting 

 the sonorous undulations of the air, and of di- 



* In this and all the following figures, the parts of the right 

 ear are shown, and, similar parts are always indicated by th(; 

 same letters. 



