Evening star. [volume] (Washington, D.C.) 1854-1972, 1913-09-07
SOUND THAT is NOISELESS
BY DONALD CAMERON SHAFER

beat upon the ear The vibrations of a can
non discharge are slow; yet they crash
against the ear with considerable force, pro
duc1ng great volume of noise.
EVERY day dozens of people in New York
talk with business associates or friends in
PARKWAY Chicago. Few know that it is not
actually our friends voice we hear when we
use the telephone. 1t is merely an accurate
reproduction of that voice faithfully copied
remembered, and repeated by that marvel
electricity.
If the telephone was only medium to
transmit sound waves, it would be far in
deed from the convenience it is now. Sound
travels slowly when compared with cleo
tricity or light, as the speed of sound waves
through the air is only one thousand and
ninety feet second. 1t is nine hundred and
seventy miles from New York to Chicago;
therefore it would take sound wave four
thousand seven hundred seconds to travel
the distance-supposing of course, it was
possible for sound to travel that far and be
audible This equals seventy-eight min
utes, or an hour and eighteen minutes
Therefore, if you said "Hello!' in this end
of sound wave line. you would have to wait
two hours ana thirty-six minutes to get an
answer from Chicago. AT this rate of speed
if a man had much to say, he might better
take fast train and go to Chicago-not to
mention what the tolls would be for ordinary
conversation at the usual rates.
Without electricity it would be impossible
to talk from New York City to Chicago or
Denver, as we can very easily do today
Sound waves would not carry outside the
great metropolis. What really happens is as
follows: The voice causes a thin metal
diaphragm in the telephone to vibrate in
sympathy with the voice. This vibrating
disk oscillates in front of a small magnet
which sends little currents of electricity
along the wires, which are in turn repeated
to a similar magnet on the other end of the
line. This second magnet, influenced by the
electricity from the first diaphragm. causes
the diaphragm in its receiver to vibrate Just
as the first one did, and of course in vibrating
it repeats in Chicago what was said to it in
New York in exactly the same tone.
Electricity travels at a speed of hundred
and eighty-six thousand miles second This
issonearly instantaneousth that it can be meas
ured only with most delicate Instruments
The time it takes electricity, carrying the
human voice, to GO from New York to Chi
cago is so infnitesimally small that it can
hardly be recorded in comprehensive figures
Therefore, the modern telephone is nearly
instantaneous.
THE human voice is produced mechanic
ally. Edison proved this when he made
a machine out of wood, wax, and iron that
would talk. Words are nothing but vibra-
tons in the air produced by similar vibra,
tons of cords in the larynx; therefore, a
common metal disk can be made to make
these same vibrations and actually repeat
the human voice.
The speaking tube is the only telephone
that actually transmits sound waves in the
air. Sound will also travel through metal,
water, gases, and mostly any other solid or
gaseous substances, and is greatly muffled
by soft fibers, such as wool, cotton, sawdust,
dirt, etc.
In many respects sound waves are like
light waves. They may be reflected, re-
fracted, or bent out of their natural course,
or diffracted, sent through an open window,
or hole in building; but they travel very
slowly, because their way through the air
is SO difficult, and they soon lose their force
and die out.