44$ Mr. Cooper's Observations on the 
the vestibule, cochlea, and semicircular canals ; these were filled 
with a substance of the consistence of cheese, instead of the 
fluid which they usually contain. From a defect like this, deaf- 
ness could not fail to arise; for, as the substance occupying 
the place of the watery fluid could not be made to undulate 
by the motions of the membrane of the fenestra ovalis and ro- 
tunda, all impressions upon the auditory nerve were completely 
prevented. 
I have thought it right to describe the foregoing instances of 
deafness, because they are liable to be confounded with that 
which arises from a closed Eustachian tube. Others might per- 
haps have been added; but various professional engagements 
have prevented me from devoting so much time to this subject 
as I am confident it merits. I have, however, the pleasure to 
reflect, that several individuals have been restored to society, 
who were before almost incapacitated from its enjoyments. I 
hope others will be induced, by this success, to second my 
feeble efforts, and to direct their attention to a subject which 
appears to be of the highest importance, and to have been too 
much neglected by medical men ; for a knowledge of the struc- 
ture of the ear is by no means general in the profession, and 
still less are its diseases understood. A prejudice has prevailed, 
that the ear is too delicate an organ to be operated upon, or, as 
it is commonly exprest, tampered with ; and thousands have thus 
remained deaf for the rest of their lives, who might have been 
restored to hearing, had proper assistance been early applied. 
But this prejudice, it is hoped, will now be done away ; since 
it appears, that the part which has been thought most essential 
to hearing, viz. the membrana tympani, may be injured by 
disease, or may be broken by violence, without a deprivation 
