( 
540 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
and efficient. Comparative constancy, wide range, compactness and port¬ 
ability adapt it to testing the hearing of large numbers of persons at 
different times and places, and it has been used in testing the hearing 
of about fifteen hundred deaf-mutes in New York, Washington, New 
Jersey, Illinois, and Arkansas. Comparative tests and subsequent train¬ 
ing demonstrate that not less than 15 per cent, of these possess utilizable 
hearing, requiring systematic education and the judicious use of special 
appliances for satisfactory results. 
Sexton’s binaural conversation tube, Currier’s duplex tube, Maloney’s 
otaphone, an audiphone, and an English conical tube were exhibited. 
In 1888 twenty-four American schools reported 261 pupils under auric¬ 
ular training. Certain cases present interesting and novel phenomena 
for the psychologist and many throw light upon problems in physiology- 
The writer’s notes briefly discussed hypnotic experiments with a view 
to the alleviation of deafness; also European experiments in auricular 
development. 
In certain cases the evidence of improvement in the auditory apparatus 
appears to be conclusive. In the majority of cases the improvement may 
be in sense-perception. It is not claimed that hearing is restored, nor 
that hearing is supplied where none existed, but simply that in certain 
cas'es rudimentary or dormant hearing may be detected and developed to 
a useful extent, thus giving to a large percentage of “ deaf-mutes ” much 
of the profit and pleasure gained through what is to them practically, if 
not scientifically, a new sense. 
337th Meeting. May 11, 1889. 
President Eastman in the chair. 
Twenty-nine members present. 
The Chair announced the election to membership of Mr. 
Wilbur Olin Atwater. 
Mr. Arthur Keith read a paper on The Rocks of the Great 
Smokies and Their Age. 
Mr. D. C. Chapman made a communication on A New. Form 
of Galvanometer. 
[Abstract.] 
This instrument was devised and constructed in response to a demand 
for a cheap and convenient means of comparing heavy currents with a 
fair degree of accuracy. 
Its coil consists of a number of heavy copper rods or bars placed par¬ 
allel to each other and secured by transverse bars or blocks of copper into 
