GENERAL MEETING. 43 
direction of sounds proceeding from points below the observer. In 
this connection he directed attention to experiments relating to 
Binaural Audition which he had communicated to the American 
Association for the Advancement of Science in 1879;* and he 
recommended any one who placed reliance on the testimony that 
had been adduced relating to the direction of the earthquake noises 
to try the following experiment: 
To one end of a long pole attach an ordinary electric call-bell, 
and at the other end place a push-knob, by means of which the ex- 
perimenter can at will ring the bell. Let the person whose credi- 
bility as a witness is to be tested stand with his feet considerably 
apart, with his eyes closed and head still. The experimenter can 
then silently move the call-bell into any desired position before 
ringing, and the observer can indicate his appreciation of the direc- 
tion of the sound by pointing to the place from whence he conceives 
it to have emanated, 
Such being the disposition of the parties the experiment Mr. Bell 
would recommend is the following: Carefully and silently intro- 
duce the end of the pole between the legs of the observer so that 
the bell is directly underneath him. Now ring and ask your wit- 
ness to indicate by pointing the position of the bell. He had tried 
the experiment many times, and had been surprised, and even 
startled, by the result. The observer usually formed a distinct 
judgment as to the direction of the sound, but the one feature that 
was common to all the experiments was that the indicated direction 
was wrong. 
Mr. GitBert remarked that the simultaneous occurrence of deto- 
nations and tremors indicated that the sound waves were identical 
with some at least of the waves constituting the earthquake. It was 
therefore legitimate to compare the velocity of transmission of the 
earthquake waves with the velocity of transmission of sound in vari- 
ous media, and such comparison indicates that the portion of the 
crust traversed by the earthquake waves was characterized by an 
elasticity between that of gold and that of iron. 
Mr. Bex thought that deductions based upon the assumption 
that the disturbance had been propagated with the velocity of 
* The paper was published in extenso in the American Journal of Otology 
for July, 1880, vol. II, p. 169. See also Nature, vol. X XI, p. 310, and vol. 
XXII, pp. 586-7. 
