5do Proceedings of Societies . [July, 
entire scale. This is the case with those who are very deaf, as 
well as with those who hear readily. The effeCt of filling the 
chest and holding the breath makes a difference in listeners. 
The capacity for hearing is for a few seconds increased by holding 
the breath. Holding the breath with the chest not full fails to 
produce the same result. As a rule, the hearing of persons who 
are right-handed is most refined in the right ear, and as most 
persons are right-handed it is found that the right ear is the best 
ear. This rule is, however, attended with many exceptions, 
since, for various reasons, some persons who use the right hand 
exclusively, practise for some particular purpose the use of the 
left ear, upon which that ear becomes more acute. Connected 
with the last-named faCt is another, namely, that by this instru- 
ment the deaf are found to fail in capacity of hearing not only 
by reason of physical defeCt, but also by failure of memory of 
sounds. Thus in a youth who had suffered serious defedf of 
hearing for seven years, owing to partial destruction of the tym- 
panum, and who in the right ear could only detect sound at 107°, 
there was an inability to catch all the sound lying between 130° 
and 107°, until he could remember what he had to listen for. 
By practising him then to detect the lowest sound that he was 
physically capable of receiving, the author got him to detect this 
one sound more readily than those which came higher up. By 
further practice all the intervening sounds became audible with 
equal facility. These facts, which have been confirmed by ano- 
ther observation on a different person, seem to indicate that 
deafness from imperfection of the tympanum or other parts of 
the organ of hearing may be increased, beyond the mere phy- 
sical failure, either from some lost power of automatic adjust- 
ment in the auditory apparatus or from failure of receptive power 
in the cerebrum itself, so that the memory rendered imperfect is 
slow to assist the listener until by exercise of function its readi- 
ness is restored. By use of the audiometer the influence of 
atmospheric pressure on hearing is detectable. In the author’s 
own case, when the barometer is at 30° he can hear on both sides 
close down to zero, but below 30° he fails by 2 0 on the left side 
to reach zero. Dr. Richardson has tried to determine in some 
of the lower animals whether there is the same sense of hearing 
as in man. In most animals it is difficult to obtain sufficient 
quietude to enable the observer to gather from expression or 
movement of the animal the information sought for. In two 
dogs — one a terrier, the other a field spaniel — he succeeded in 
making some good observations, and in them the range of 
hearing power seemed to be distinctly lower than it is in the 
human subjeCt who has perfect hearing. In both these animals, 
which were healthy and in the prime of life, the first indication 
of the detection of sound commenced at io° on the scale. The 
detection was evidenced by the sudden expression of listening, 
by a slight change of position, and a slight dilatation of the 
