Burlington weekly free press. [volume] (Burlington, Vt.) 1866-1928, 1877-06-01
The Telephone.
THE HUMAN VOICE CARRIED HUNDRED AND
FORTY MIIFs

The HUMAN VOICE CARRIED HINDhEb AND
FORTY MILES.
Professor A. Graham Bell, the inventor of
the telephone, comes from the staid old city
of the witches Salem, Mass. He is pro-
fessor of vocal physiology" III the Boston
University. About five years ago he first be-
gan to think about the possibility of the
transmission of sound by telegraph, and the
idea took possession of him completely.
The first time the practical success of the
telephone was demonstrated to the satisiac-
ton of others was on Oct ., 1876, when an
experiment was made over the private wire
OF the Walworth Manufacturing Company, of
Cambridge. The telephone then spoke for
itself, and the conversation OF the operator
in Cambridge could be distinctly heard at the
Boston end of the line. An interesting din
logue took place, the speakers talking in
their ordinary key. The experiments were
continued almost constantly. Onel of the
experiments, between Boston and Salem,
which occurred on January 2lst, was emi-
nently gratifying i'll its results. Not only
every word spoken in Boston, but even the
tones and infections of the several voices
were accurately transmitted and readily re-
cognized by those at the Salem end of the
line. Other experiments demonstrated the
fact that n lady IN Maiden could sing 1.-The
Last Rose of Summer, and every note could
be heard IN the room at . Exeter Place, Bos-
ton. The sound was perfectly clear, and had
about the same effect as if the listener Were
at the rear of a concert hall. say 100 feet
away from the singer. Subsequent TRIALS
showed that laughter, applause or instru-
mental music could be equally well trans
mitted. In the case OF the latter not only
the key could be transmitted, but also the
quality OF the music.
he. list he,
quished by the telephone is lI3 miles from
Boston to North Conway, y. ii. The most
recent improvements made on the instru-
ment do away with batteries altogether, and
permanent magnets are now employed III
stead, tho electric wave used i'll transmitting
the sounds being generated 10y the voice IL
self. This is regarded ms very important
step in advance, as the bother and expense of
keeping batteries III order has been the great
drawback to the employment OF the mstru
ment for private purposes.
al haven't the slightest doubt, MIR. Wat
son says. that in IL few months things will
he that II man can make lecture here III
Boston, and be heard by Rn audience III any
part of the country"
The wonderful little instrument consists of
u powerful compound permanent magnet, to
the poles of which are attached ordinary
Telegraph coils Of insulated wire. In front
of the poles, surrounded 10y these coils Of
wire, IL IL diaphragm of iron. mouthplece,
whose function IL To- converge the sound
upon tins diaphragm. substantially completes
the arrangement. The operation of the i'll
strument is thus described by Prof Bell: The
motion of steel or iron i'll front of the poles
of magnet creates current of electricity
in coils surrounding the poles of tue mag
net and the duration of this current of clec-
tricity comedies with the duration OF the mo-
tion Of the steel or iron moved OF vlbrnted
in the proximity OF the magnet When the
human voice causes the diaphragm to vi
brnte, electrical undulations are induced III
the coils around the magnets precisely simi-
lar to the undulatiuns OF tho uIr produced 10y
the voice The coils ARE connected with the
line wire. and the undulntions produced III
them travel through the wire. and passing
through the coils OF another instrument OF
similar construction ut the other end OF the
line, are again resolved into air undulations
by the diaphragm of this instrument. The
voltaic battery is entirely dispensed with.
The line wire may ho of any given length.
provided the insulation bo good Professor
Bell further says that soft tones can he heard
across the wires even more distinctly than
| loud uttcrances. even whisper being audi
| bile. thriStdIt OJSpru.