i 879-1 
Proceedings of Societies . 
501 
pupils. This detection was clearly made on the instant, as it 
the sharp line of hearing were the same in them as it is in the 
higher animal. 
The following practical memoranda are given by the author : — - 
“ 1. The audiometer will, I think, be an essential in all phy- 
sical examinations of men who are undergoing examination as 
to their fitness for special services requiring perfect hearing, such 
as soldiers, sentries, railway officials, and the like. 
“ 2. The instrument will be of great use to the physician in 
determining the value of hearing in those who are deaf, and in 
determining the relative values of the two organs of hearing. 
In one instance, already, I have been able by its means to detect 
in a person who was supposed to be equally deaf on both sides, 
that on one side the hearing is perfect close up to zero, while on 
the other side nine-tenths of the hearing is lost. 
“ 3. In other forms of diagnosis I have found the instrument 
useful. In a young person suffering from acute anaemia the 
hearing was so defective that on the right side it failed to detect 
sound at 18 0 , and on the left side at 15 0 . In ten days, during 
which, under a new regimen, great improvement took place in 
strength and general condition, the power of hearing had so 
much improved that the right ear was good down to 12 0 , and the 
left to 3 0 , — an improvement of 6° on the right, and of 12 0 on the 
left side. In another person, who was subject to repeated ver- 
tigo, the giddiness occurring three or four times a-day, the 
hearing was so defective that although the external ear on each 
side was clear and the tympanum natural, no sound could be 
heard below 30°. Under complete rest and attention to diet the 
vertiginous attacks were in a few days removed altogether, and 
with that removal there was gain of hearing, on both sides 
equally, up to 5 0 on the audiometric scale-. 
“ 4. The instrument may be used to differentiate between 
deafness through the external ear and deafness from closure of 
the Eustachian tube — throat deafness. In my own case I fail to 
detect sound by the mouth at 170°, and this I find is a fair ave- 
rage in those who are healthy. It represents the comparative 
value of communication by sound through the Eustachian canal 
and the external ear. 
“ 5. The instrument promises to be very useful in detecting 
the effedts in the body of those agents which quicken or excite 
the circulation, such as alcohol and other similar chemical sub- 
stances. 
“ 6. The instrument promises to be of great service in deter- 
mining the value of artificial tympanums in instances of deafness 
due to imperfedtion or destruction of the natural tympanum. 
The cotton artificial tympanums introduced originally by the late 
Dr. Yearsley, and the membranous tympanums introduced by the 
late Mr. Toynbee, F.R.S., have proved of much service; and by 
means of the audiometer I have been able very accurately to test 
their respective merits, and to compare both with tympanums 
