Destruction of the Memhrana Tympani. 445 
and inferior part of the membrane 5 under the manubrium of the 
malleus, which must not be injured in the operation ; and it is 
therefore necessary that the operator be acquainted with its 
exact situation. 
Though the membrana tympani be vascular, the vessels are 
so small that they bleed but little ; and therefore, if much 
blood is discharged, the operation cannot have been properly 
performed. 
In an ear otherwise healthy, the operation is attended with so 
slight a degree of pain, that when it has been performed in one 
ear, the patient expresses no unwillingness to submitting to it 
in the other. The sensation which it occasions is momentary \ 
and no subsequent inconvenience of any kind arises. * 
As this operation will not afford relief in any cases of deafness, 
except such as arise from a closed Eustachian tube, I am anxious 
that it should be performed in those only which are clearly of 
that description. The criteria by which I judge whether the 
tube is closed or open are the following. 
First, If the person in whom it is suspected to be closed, 
should feel, in blowing the nose violently, a swelling in the ear, 
from the membrane being at that time forced outward, the tube 
is open ; for, when closed, no such sensation is produced. 
Secondly, The Eustachian tube may be closed, yet the beat- 
ing of a watch may be heard, if it be placed between the teeth, 
or pressed against the side of the head; and, if it cannot be heard 
when it rests upon the teeth, this operation cannot relieve, as 
the power of the auditory nerves must have been destroyed. 
* If the ear has been previously irritated by stimulating applications to the meatus, 
the operation will then be painf ul ; it is therefore proper to wait until the inflammation 
has subsided. 
