POWER OF HEARING OF FISH. 225 



when the watch is brought close to the ear, but if 

 we convey the watch to a greater distance from 

 the ear and press it against the teeth, or if we 

 rest one end of a rod of wood against the watch 

 and the other against our head, we hear the tick- 

 ing with remarkable distinctness. In the language 

 of science, solid and dense bodies vibrate with 

 greater intensity than lighter media, such as the 

 atmosphere. When the watch is held nigh to the 

 ear the atmosphere is the conductor ; when the 

 watch is connected with the ear, by the interven- 

 tion of a rod of wood, or the solid parts of the 

 head, these are the conductors. Now the appa- 

 ratus of hearing of the fish presents conditions of 

 the latter kind ; water, a denser body than air, is 

 the conducting medium; and the solid mass of 

 the head, and, in fact, of the entire body, com- 

 pletes the conduction to the vital apparatus. 

 Hence in fishes, an humble contrivance is capable 

 of effecting the same end as the high-toned in- 

 strument of terrestrial animals. Fishes must, 

 therefore, hear with moderate acuteness, particu- 

 larly such sounds as occasion a vibration of the 

 element in which they reside ; for example, an 

 approaching footstep ; while the sounds which 

 proceed from musical instruments, being less 

 easily conveyed, are probably unknown to them ; 

 certainly this is the case with regard to tone. 

 Those curious porcelain-like bodies, which are 

 Q 



