TIFIC MISCELLANY.

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THE TELEPHONE.

Great interest in telegraphic subjects has lately been aroused in the
American public by exhibitions of the telephone, an instrument for
transmitting sound vibrations by electricity. Two general forms of this
instrument are known, in one of which a series of tuning forks
communicates with a precisely similar series at the other end of the
wire, and the signals made to one are repeated by the other. A more
interesting form, and the one that has lately attracted so much
attention, is that which receives and transmits ordinary vocal sounds.
The operator talks to a membrane, and at the other end of the wire is a
resonator of some kind which talks to the auditor there. The fundamental
idea of the machine is not new. It was at first proposed to use it for
transmitting electric signals without a wire, and in that view a trial
was made with it during the siege of Paris. The armistice interrupted
the operations, but M. Bourbouze, the experimenter, and other inventors
have continued to study the subject, Mr. A. G. Bell, professor of vocal
physiology in Boston, being among them. M. Bourbouze used a vibrating
needle the movements of which were effected by sound waves, and another
Frenchman, M. Reuss, introduced the sounding box with its membrane. This
is a box with a membrane stretched over the top and a short tube of
large diameter in the side. The operator talks to this tube, and the box
strengthens the sound, which finally affects the membrane, causing it to
vibrate. Resting upon this membrane is a thin copper disc attached to a
wire leading from the electrical battery. Above and very near it hangs a
metallic point, which forms the end of a wire leading to the place to
which the message is to be sent. The membrane rises slightly with every
vibration, and touching the point, a current is established and
communication effected with the distant point; but this communication
ceases as soon as the vibration stops, and the membrane assumes a state
of rest. As every simple note is produced by a definite number of air
vibrations, and every compound sound is made up of the sum of several
simple notes, the apparatus transmits a definite number of vibrations
for each sound which it receives; and if those vibrations can be
communicated to the air at any point, however distant, the original
sounds will be reproduced. In short, the instrument may be expla