46 MAMMALIA-MAN. 



tion, it is true, are less distinctly understood than thost? of light: all we 

 know is, that sound is principally reflected by hard bodies, and that their 

 being hollow also sometimes increases the reverberation. The internal 

 cavity of the ear, which is fashioned out in the temporal bone, like a cavern 

 cut into a rock, seems to be fitted for the purposes of echoing sound with 

 the greatest precision. 



One of the most common complaints in old age is deafness ; which proba- 

 bly proceeds from the failure of the nerves, in the labyrinth of the ear. 

 This disorder also proceeds sometimes from a stoppage by the wax, which 

 art may easily remedy. In order to know whether the defect be an internal 

 or an external one, let the deaf person put a repeating watch into his mouth, 

 and if he hears it strike, he may be assured that his disorder proceeds from 

 an external cause, and may be in some measure cured. 



It often happens that people hear better with one ear than the other ; and 

 these, it is observed, have what musicians call a bad ear. Buffon made 

 many trials on persons thus circumstanced; and he always found that 

 their defect in judging properly of sounds, proceeded from the inequality of 

 their ears, and their receiving, by both at the same time, unequal sensations. 

 In like manner, as such persons hear false, they also, without knowing it, 

 sing false. They also frequently deceive themselves with regard to the side 

 whence the sound comes, generally supposing the noise to come on the part 

 of the best ear. 



Hearing is a much more necessary sense to a man than to animals. In 

 these it is only a warning against danger, or an encouragement to mutual 

 assistance. In man, it is the source of most of his pleasures ; and with- 

 out it the rest of his senses would be of little benefit. A man born deaf, 

 must necessarily be dumb; and his whole sphere of knowledge must be 

 bounded by sensual objects. We have a singular, and perhaps an unex- 

 ampled instance of a young man, who, being born deaf, Avas restored, 

 at the age of twenty-four, to perfect hearing. The account, which is given 

 in the memoirs of the Academy of Sciences, 1703, page 18, is in substance 

 as follows : 



"A young man of the town of Chartres, between the age of twenty-three 

 and twenty-four, the son of a tradesman, and deaf and dumb from his birth, 

 began to speak all of a sudden, to the utter astonishment of the whole town. 

 He gave them to understand that, about three or four months before, he had 

 heard the sound of the bells, and was greatly surprised at this new and un- 

 known sensation. After some time, a kind of water issued from his left 

 ear and he then heard perfectly well with both. During these three months 

 he was sedulously employed in listening, without saying a word, and accus- 

 toming himself to speak softly, so as not to be heard, the words pronounced 

 by others. He labored hard also, in perfecting himself in the pronunciation, 

 and in the ideas attached to every sound. At length, having supposed him- 

 self qualified to break silence, he declared that he could now speak, though 



