22 CHELTENHAM COLLEGE NATURAL HISTORY SOCIETY, 
40,000 , but the power of hearing high notes is rapidly lost with age, 
and few persons over 50 can hear the cry of a mouse or a bat. 
The essential part of the human ear where the hearing nerve 
comes in contact with the sound vibrations lies deeply buried in the 
bony structure of the skull, and sound may be brought to it from 
without either through the solid bone, as happens when the head is 
under water, or by the conducting apparatus which we call the Ear. 
This may be divided naturally into the Collecting portion, the 
Conducting portion, and the Receiving portion. 
We have only to observe a nervous horse to understand the use to 
which the outer ear is put in collecting sound. Our own ears do not 
move, but we instinctively increase the collecting area by our hollow 
hand when sounds are indistinct. 
Sound thus collected strikes the drum which takes up the vibra- 
tions and transmits them by three small bones,—the mallet, the anvil, 
and the stirrup bones, (which serve the double purpose of transmitters 
of sound and dampers to the drum) across the air-space of the middle 
_ ear to a second membrane by which the vibrations are passed on to 
“the fluids immediately surrounding the auditory nerve fibres in the 
_ semicircular canals and the Cochlea. 
The connection of the semicircular canals with the power of main- 
| taining the equilibrium of the body was explained, as well as the in- 
its first appearance in birds. How the vibrations conveyed to the 
/nerve fibrils, and carried by them to the brain, are there interpreted 
‘and converted into ideas, it is impossible even to conjecture ;—but it 
is in the brain that the true organ of hearing lies, and excitement from 
“duce sounds as real to us as any heard from without ; and voices thus 
roduced are not an uncommon experience, as many as 1 in go per- 
The Ear is by far the most complicated of all the organs of Special 
| Sense, and presents a fertile field for further investigation. 
On the conclusion of the Lecture a most hearty vote of thanks to 
r. Wilson was proposed and carried unanimously. 
