M A N 
MAN 
and infenfible, they can receive and refieft founds 
only while the nerves poffels the power of produc- 
ing fenfation. Now, in the organ of hearing, the 
only nervous part is a portion of the fpiral lamina ; 
all the rell is folid : hence this part may be re- 
garded as the immediate orga.T of hearing, as may 
be proved by the fubfecjuent refleftions. 
rhe external ear is only an acceffory to the in- 
ternal: it's Concave windings may augment the 
quantity of found; but we can hear very well 
without the external ears, as appears from dogs 
and other animals v/hich have thefe organs ampu- 
tated. Nor is the membrane of the tym.panum 
niore elTcntial to the perception of found than the 
external ear; for-many have heard diitin(5lly after 
this organ was either totally or partially deftroved. 
The f^micircular canals, hov^^ever, appear to be 
more necefiary : thefe are a kind of winding tubes 
in the os petrofum, that feem to dire6l and con- 
duct the fonorous particles to the membranous 
part of the cochlea, on which found ads, and it's 
fenfation is produced. 
One of the rnoft common diforders incident to 
old age, is deafnefs, which probably proceeds from 
the rigidity of the nerves in the labyrinth of the 
ear. This diforder alfo fometim.es arifes from a 
ftoppage of the wax, which art may eafily remedy. 
In order to difcover whether the defefi: be an in- 
ternal or an external one, let the deaf perfon put 
a repeating Vv'atch into his mouth; and, if he hears 
it ftrike, he may be aflured that his diforder pro- 
ceeds from an external caufe, and is in fome mea- 
iure curable : for there is a paffage from the ears 
into the mouth by what anatomifts call the eufta- 
chian tube; and by this paflage people often hear 
founds when they receive none through the larger 
channel; and this alfo is the reafon why we often 
fee perfons Vv^ho liften with great attention, hearken 
with their mouths open, in order to admit the 
found by every aperture.' 
It has often been remarked, that thofe who have 
unmufical ears, and bad voices, hear better with 
one ear than the other. Buffon, who made many 
experiments on perfons of this defcription, aUvays 
found that their defeft in judging properly of 
founds proceeded from the inequality of their 
ears; for as they receive by both unequal fenfa- 
• tions at the fame time, they muft neceiTarily form 
an tmiufl: idea. In this manner, as thole people 
■ hear falfcly, they alio, v/irhout being confcious of 
it, fing faliely. Such perfons are alfo frequently 
deceived with regard to the fide from whence the 
found arrives, generally ilippCfing it to come on 
the part of the belt ear. 
Trumpets or funnels, employed in afllfting the 
hearing, anfwer the fame end as convex glaffes to 
old or decayed eyes. The parts neceffary to hear- 
ing, as well as thofe elTential to vifion, become ob- 
tufe and infenfible through age; and therefore 
each of them equally requires the affiftance of art 
to augment the quantity of the medium through 
which their peculiar ienfations are tranfmitted. 
Trumpets for facilitating hearing might be ren- 
dered as extenfively ufeful to the ear as telefcopes 
are to the eye: but thefe trumpets would not be 
employed to advantage except in folitary and 
filent places; for neighbouring founds are uni- 
formly collefted and blended with thofe at a dif- 
tance, and produce in the ear nothing but a con- 
fufed noife. 
Hearing is a m.uch more neceffary fenfe to Men 
than to other animals. To the latter it is only a 
warning againft danger, or an encouragement to 
mutual affiilance ; but to Man, it is the fource of 
moft of his pleafures, and without it the reft of his 
fenfes would be of little fervice. A perfon born 
deaf muft necelTiirily be dumb; and his whole 
fphere of knowledge muft be bounded only by 
fenfual objeds, Wc have an inftance, in the Me- 
moirs of the Academy of Sciences, of a perfon 
who, though born deaf, was reftored to perfed 
ihcaring at the age of twenty-four years. The ac- 
count runs thus: 
' A young Man, of the town of Chartrcs, about 
twenty-four years of age, who had been deaf from 
his birth, began all at once to fpeak, to the utter 
aftonilhmient of all who knew him. He informed 
his friends that, for three or four months preceding, 
he had heard the lound of bells ; and that he was 
extremely furprized at this new and unknown fen- 
fation. Some time after, a kind of humour ilTued 
from his left ear, and then he heard diftindly with 
both. During thefe three or four months, he liften- 
ed to every thing; and, widiout attempting to 
fpeak loud, he habituated himfelf to utter foftly the 
words fpoken by others. After labouring hard in 
acquiring the pronunciation of words, and in learn- 
ing the ideas annexed to them, at length thinking 
himfelf qualified to break filence, he declared that 
he could fpeak, though ftill imperfedly. Soon 
after, he was interrogated by fome able divines 
concerning his former condition : their principal 
queftions turned on God, the foul, and moral good 
and evil; but of thefe fubjeds he feemed not to 
have the fmalleft conception. Though he was 
born of Catholic parents, attended mafs, and was 
inftruded to make the fign of the crofs, and to 
affume all the external marks of devotion, he had 
no comprehenfion of their real meaning. He had 
formed no diftind idea of death ; and feemed to 
exift purely in an animal ftate. Wholly occupied 
about fenfible objeds, and with the few ideas he 
had acquired by the eye, he drew no conclufions 
from them. He was by no means deftitute of abi- 
lities; but the underftanding of a Man, when de- 
prived of the intercourfe of fociety, ha fo little 
exercife or cultivation, that he never th nks but 
when fenfible objeds obtrude themfelves on his 
mind : the great fource of human ideas arifes from 
the reciprocal intercourfe of fociety.' 
Notwithftanding, it is very poffible to commu- 
nicate ideas to deaf Men which they previoufly 
wanted, and even to give them very precife no- 
tions of fome abftrad fubjeds by means of figns 
and letters. A perfon born deaf may, in time, 
with fufficient pains, be taught to write and read; 
to fpeak; and, by the motion of the lips, to un- 
derftand what is faid to him: however, it is pro- 
bable, that as mcft of the motions of fpeech are 
made within the mouth by means of the tongue, 
the knowledge arifing from the motion of the 
lips is very confined; and perfons labouring under 
the defed of hearing have always a harlli and dif- 
fonant articulation, becaufe they can form no idea 
of mufical founds, or the harmony of juft elocu- 
tion. Indeed, deaf perfons who had acquired any 
tolerable fhare of learning, were formerly regarded 
as prodigies; but there have been fo iriany in- 
ftances of fuccefs lately, and fo many Iiave gained 
celebrity in this mode of inftrudion, that, though 
ftill a matter of fome cuiiofity, it ceaies to be aa 
objed of wonder. 
'Of all the fenfes pofTeffed by Man, perhaps 
there is none in which he is more inferior to other 
animals 
