.

The sense of hearing becomes diminished, and often entirely
abolished; and this may arise from various causes, such as an
original defect in the external ear, or the meatus auditorius, or
both; the meatus auditorius is often blocked up with wax or other
substances, which being removed, the hearing becomes perfect.
Deafness may likewise arise from a rigidity of the membrane of the
tympanum, from its being erodedor ruptured, or from an obstruction
of the Eustachian tube. It may likewise arise from a paralysis or
torpor of the auditory nerve, or from some diseased state of the
labyrinth, or from a vitiated state of the brain and nerves. There
is a kind of nervous deafness which comes on suddenly, and often
leaves the patient as suddenly.

There are various instances, however, in which the membane of the
tympanum has been lacerated or destroyed, without a total loss of
the sense of hearing, or indeed any great diminution of it. A
consideration of these circumstances induced Mr. Astley Cooper to
think of perforating it, in cases of deafness arising from a
permanent obstruction of the Eustachian tube, and he has often
performed this operation with great success. Of this he has given an
account in the last part of the Philosophical Transactions. This
operation ought however only to be performed in case of the closure
of the Eustachian tube. Cases of this kind may be distinguished by
the followingcriteria. If a person on blowing the nose violently,
feel a swelling in the ear, from the membrane of the tympanum being
forced outwards, the tube is open; and though the tube be closed,
if the beating of a watch placed between the teeth, or pressed against
the side of the head, cannot be heard, the operation cannot relieve,
as the sensibility of the auditory nerve must have been destroyed. In
a closed Eustachian tube, there is no noise in the head, like that
accompanying nervous deafness.

There is one species of deafness, which occurs very frequently, and
happens generally to old persons, though sometimes to the delicate
and irritable in the earlier periods of life. Anxiety and distress of
mind have been known to produce it. Its approach is generally
gradual, the patient hears better at one time than at another; a
cloudy day, a warm room, agitated spirits, or the operation of fear,
will produce a considerable diminution in the powers of the organ. In
the open air the hearing is better than in a confined situation; in a
noisy,