Year: 1878

A correspondent requests US u
give description and explanation OF
the telephone. 1t is somewhat diff
ficult to describe without diagrams,
but We viii eDdeavor to comply with
our friends request as far as we can.


If wire from galvanie battery
be wound around a piece of steel and
current of electricity passed through
the wire, the piece of steel will be-
come magnet that will attract and
bold bits OF iron; and if the wire is
extended and wound around another
piece of steel in the same manner,
that also will become magnet sim
liar to the first. If now the two
ends of the wire be joined together,
every time pi,ce Of soft iron is
brought in contact with either of the
magnets, current of electricity will
pass through the wire, although there
is no longer galvanic battery at
tached And this will be the case
though the magnets be one mile or 8
hundred miles apart And, what is
more remarkable, these currents of
electricity may be sent through the
wire without the actual contact Of
the piece of iron with the steel bar
If the iron is brought near to one of
the magnets without touching it, and
then withdrawn, and electric thrill is
felt in the distant magnet, just as if
the contact had been made and bro
ken And so, if piece OF IRON be
moved backward and forward before
the magnet, no matter how rapidly
or slightly, each motion is felt as an
electric pulse in the magnet at the
other end We have here the funds-
mental principle of the telephone
No galvanic battery is employed to
furnish an electrical current, as in the
case of the telegraph, but the cur
rents in the wires are produced by
the emotion of a piece of soft iron
near the magnet.


Of course these motions are not
made by hand, but with delicately
constructed instrument, the import
ant part of which is a thin iron plate
suspended near the magnet, and both
of these encased in a brass tube to
which close fitting mouth piece is
attached.


1t is well known that sounds are
conveyed by waves tina. travel swift
lv from their sources. and we hear
them because these waves strike in
rapid succession upon the drum Of
the ear 1t is also understood that
these waves differ greatly and are
very complex, depending upon the
rapidity of vibration in the sounding
body, and it Is this which causes
such marked peculiarities of tone in
different musical instruments, and the
voices of differen. individuals. Now,
these waves, started by person
talking into the mouth, piece above
described, cause the thin and del
icately hung iron plate to vibrate,
and these vibrations, though they
may be ever SO delicate, will each
affect the magnet and cause move
ment of electricity through the wires,
which will affect the magnet at the
other end and cause the iron plate
there to vibrate in precisely the same
manner This gives out a new set
of air waves which, falling upon the
drum of the ear of the listener, repro
duce the original sound of voice.
The arrangement being the same at
each end, the machine. of course,
works both ways.


The telephone is much more mex
pensive than the telegraph, and easi-
er to operate. The longest distance
at which conversation has been car
ried on through it is about two hun
dred and fifty miles.