4:88 CLASS MAMMALIA. 



Every natural philosopher is aware, that the more the 

 luminous radii fall obliquely on the surface of a diaphanous 

 body, the more they are refracted in traversing it. He also 

 knows, that the refraction of the rays of light is greater 

 through a sphere, than through a flatted lens. Now the 

 crystalline of the Whale, presents a degree of sphericity, 

 of density, and inflammability, occasioned by the oily sub- 

 stance with which it is impregnated ; in a word, it has such 

 a degree of refracting force, that it compensates the defect 

 of refraction in the water. 



The Whale can hear sounds or noises comparatively fee- 

 ble, at a great distance. The meatus auditorius, is very 

 wide, and the Eustachian tube of great diameter. When 

 the animal swims along the surface of the ocean, the ear 

 is often eight or nine feet below the level of the water ; it is, 

 therefore, through the watery medium that the sonorous 

 vibrations arrive at the acoustic organ. The aqueous fluid 

 is a most excellent conductor of such vibrations, for by 

 means of currents it transmits even the most feeble sounds 

 to the greatest distances. 



When the Whale ejects by its spiracles a quantity of 

 water which falls around it with a tremendous noise, it can 

 no longer distinguish other sonorous vibrations, and 

 the whalers generally take advantage of this temporary 

 deafness, to fall upon the animal and harpoon him more 

 effectually. 



The internal ear is composed of a labyrinth, three semi- 

 circular canals, a cochlea, a cochlearian orifice, a vestibu- 

 lum, a vestibulary orifice, a tympanum, a membrana tym- 

 pani, articulated osselets, placed in the tympanum from the 

 membrane to the vestibulary orifice, a Eustachian tube, a 

 canal, which from the membrane of the tympanum opens in 

 a small hole externally, and is terminated by no vestige of 

 conch. 



On the first consideration of the spiracles of the Balsense, 



