436 Mr. Cooper’s Observations on the 
a suppuration in the meatus auditorius. In persons of a delicate 
constitution and irritable habit, the wax secreted in the ear is 
liable to be hardened; this, by filling the meatus auditorius, 
gradually occasions deafness, and then excites inflammation 
and suppuration. In this case, if no mode of relief be resorted 
to, not only will the membrane lining the meatus, but also the 
membrana tympani itself be destroyed, the small bones of the 
tympanum discharged, and sometimes considerable exfoliations 
produced. 
The membrana tympani is also not unfrequently injured by 
means of external violence. In Plate XXXIII. Fig. 4, a view 
is given of the membrane lacerated in different directions, by a 
blow upon the side of the head ; an effect which probably was 
occasioned by the air in the meatus having been driven with 
violence upon the membrane. 
The membrana tympani is also sometimes broken by at- 
tempts to remove extraneous bodies, which have been thrust 
into the meatus auditorius. Children, in their thoughtless pranks, 
often introduce small stones, pieces of slate-pencil, and even pins 
into their ears ; in extracting which, I have known considerable 
lacerations made in the membrana tympani. Fig. 5, shews 
the membrane broken perpendicularly, in an attempt to remove 
a pin, which had been accidentally dropped into the meatus. 
The membrana tympani may be easily seen in some persons, 
by directing the rays of the sun, or a condensed light from a 
common lamp, into the ear ; but this is not the case in all ; for 
the meatus differs considerably in different persons, both in its 
depth and diameter. 
If the ear is clear from wax, the membrane has a bright ten- 
dinous appearance; and an aperture in it appears as a dark 
