"Resistance of the wire, when
heated by the current," lie explajned,
"alternately is increased and reduced
by sound. The fluctuating current
represents sound waves, which n,jsre
transmitted to reproducing machines,
and so made audible to the human
ear."
Successful recordings already had
been made above the limits of audi
bility, he said, and the highest notes
of the violin and flute had been re
produced with perfect clarity and
fidelity to pitch.
While experiments had not been
made on insects of animals, be ex
pressed belief that any inaudible
sounds they might make could be
recorded.
Dr. De Forrest asserted that the
principle of the thermophone which
he developed in conjunction with T.
W. Case of Auburn, N. Y., was en
tirely new, while that of the ultra
audible microphone had been used
20 years ago in a radio telephone,
on which he himself held a patent.
Its present perfection, he said, was
due largely to the use of amplifiers
in connection with the discharge be
tween electrodes.
Refinement of the process to the ex
tent of recording Inaudible sound
vibrations, he said, was'a remarkable
achievement.
PI\ DROP A •‘CRASH*’
LONDON, Dec. 30.—You could have
heard a pin drop, my dear—a familiar
utterance. Now science has found a
way to make a pin drop with a crash.
Dr. J. H. T. Roberts, giving a prac
tical demonstration along with his
lecture on "the wonders of wireless"
At the Westmister Central Hall, em
ployed amplifiers, and magnified the
sound of a pin dropping to the floor
to that of a crowdbar. Salt was poured
out, and sounded like rocks falling.
1, ,\ PLEASANT TRUTH
The teacher, a woman of uncertain
age, was having a hard time getting
Johnny to memorize the name of the
Presidents.
