ANIMALS. 



167 



diffused, but are frequently reflected. The 

 laws of this reflection, it is true, are not as 

 well understood as those of light ; all we 

 know is, that sound is principally reflected 

 by hard bodies ; and their being hollow; also, 

 sometimes increases the reverberation. " No 

 art, however, can make an echo ; and some 

 who have bestowed great labour and expense 

 upon such a project, have only erected shape- 

 less buildings, whose silence was a mortifying 

 lecture upon their presumption." 



The internal cavity of the ear seems to be 

 fitted up for the purpose of echoing sound 

 with the greatest precision. This part is fa- 

 shioned out in the temporal bone, like a ca- 

 vern cut into a rock. " In this the sound is 

 repeated and articulated ; and, as some ana- 

 tomists tell us, (for we have as yet but very 

 little knowledge on this subject,) is beaten 

 against the tympanum, or drum of the ear, 

 which moves four little bones joined thereto; 

 and these move and agitate the internal air 

 which lies on the other side; and lastly, this 

 air strikes and affects the auditory nerves, 

 which carry the sound to the brain." 



One of the most common disorders in old 

 age is deafness ; which probably proceeds 

 from the rigidity of the nerves in the labyrinth 

 of the ear. This disorder, also, sometimes 

 proceeds from a stoppage of the wax, which 

 art may easily remedy. In order to know 

 whether the defect be an internal or an ex- 

 ternal one, let the deaf person put a repeat- 

 ing watch into his mouth, and if he hears it 

 strike, he may be assured that his disorder 

 proceeds from an external cause, and is, in 

 some measure, curable : " for there is a pas- 

 sage from the ears into the mouth, by what 

 anatomists call the eustachian tube ; and, by 

 this passage, people often hear sounds, when 

 they are utterly without hearing through the 

 larger channel : and this also is the reason 

 that we often see persons who listen with 

 great attention, hearken with their mouths 

 open, in order to catch all the sound at every 

 aperture." 



It often happens, that persons hear diffe- 

 rently with one ear from the other ; and it is 

 generally found that these have what is call- 

 ed, by musicians, a bad ear. Mr. Buffon, 

 who has made many trials upon persons of 

 this kind, always found that their defect in 



judging properly of sounds proceeded from 

 the inequality of their ears ; and receiving by 

 both, at the same time, unequal sensations, 

 they form an unjust idea. In this manner, as 

 those people hear false, they also, without 

 knowing it, sing false. Those persons also 

 frequently deceive themselves with regard to 

 the side from whence the sound comes, gene- 

 rally supposing the noise to come on the part 

 of the best ear. 



Such as are hard of hearing, find the same 

 advantage in the trumpet made for this pur- 

 pose, that short-sighted persons do from 

 glasses. These trumpets might be easily im- 

 proved so as to increase sounds, in the same 

 manner that the telescope does objects ; how- 

 ever, they could be used to advantage only 

 in a place of solitude and stillness, as the 

 neighbouring sounds would mix with the more 

 distant, and the whole would produce in the 

 ear nothing but tumult and confusion. 



Hearing is a much more necessary sense to 

 man than to animals. With these it is only 

 a warning against danger, or an encourage- 

 ment to mutual assistance. In man, it is the 

 source of most of his pleasure; and without 

 which 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 only by sensual objects. 

 We have an instance of a young man, who, 

 being born deaf, was restored at the age of 

 twenty-four to perfect hearing : the account 

 is given in the Memoirs of the Academy of 

 Sciences, 1703, page 18. 



A young man, of the town of Chartres, be- 

 tween 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 great 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 for the first time, 

 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 laboured hard also in perfecting himself 



