The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1894-01-14
A LIGHT TOPIC.
wealth.

TO indicate or describe them. Among them
is the searchlght. As the thing itself is
of comparatively recent origin, so the word
is only found in the latest dictionaries. =
generation ago the searchlight had not
been heard of; now it has very important
uses on sea and on land. IL is an important
factor in naval and military operations. 1t
is used on merchant ships to light up intri-
cate channels at night and on men-of-war
to detect the approaches of torpedo boats
or other enemies On land 1t has uses in
civil as well as N military life. In addition
to its practical application it has come to
have a figurative one. as applied to the
probing of a mystery, the uncovering of
fraud the illuminating of a dark subject
So words born and get new meanings.
The question what is light is more easily
asked than answered. Science define
some OF its conditions, attributes and modes
of action, but it cannot tell what it is any
more than it can tell what electricity is.
Science can generate, store, control, utilize
and apply electricity. but 1t cannot tell
what electricity is. Scientists can write
volumes about the subtle fluid, but they
cannot define it. We know that it exists
as a tremendous and almost universal force
of nature, and that is about ALL Light is
defined as that which makes things visi-
ble," but how? Does it exist in the thing
itself, or is it set in motion by the thing?
By what medium mode of transmission
does it reach the eye? Electricity travels
on or through certain solid substances; how
does light travel? Scientists used to hold
that light consisted Of minute material
particles, which were emitted by the lum-
inous body and travelled through space in
all directions from it with immense veloci-
ty. This was the corpuscular theory of
light. generally accepted theory now
is that light is kind Of undulatory mo-
ton produced by the luminous body in the
particles of an elastic, imponderable me-
dunn called the luminiferous ether, which
is supposed to fill all space. This undula.
tory motion is supposed to be propagated
in waves in all directions from the lurnin-
Gus body and to travel with velocity, in
q vacuum, of about $4,000 miles a second.
When this undulation strikes ones eye
one experiences the sensation called seeing.
babe can see, but the wisest scientist
cannot tell what seeing is beyond defining
it as a sensation caused by the contact of
what is called light with the machinery
of the eye. What would light be without
the eye? If there were no eyes, would there
be any light or any colors?
A strong searchlight in action at night is
beautiful, impressive and instructive
sight. The powerful propulsion of a broad
beam of light across the sky, piercing and
scattering the darkness instantaneously, is
a fine object lesson in the forces Of nature.
1t is noticeable that the light reaches its
furthest point as soon as it does the near
est Why not, when it travels at the'rate of
about $4,000 miles a second? The circum-
ference of the earth being about
$4,000 miles, a ray of light would
encircle it in less than one-seventh
of a second - that is, it would If light
could travel in any other than a
straight line. No wonder. then, that the
rays of searchlight. which only extend a
few miles at furthest, seem instantaneous
in their action AS they sweep across the
sky in Migratory motion they easily be
compared to the tail of some monstrous
comet whose head is buried in space. They
furnish a fine Illustration of the familiar
for nothing breaks or bends them They do
not condescend to turn aside to illuminate
anything Nothing could induce them to
turn corner. Their mission is to dart in
simultaneously on a straight line to the
furthest point they are capable of reaching
and that they do in strict conformity to the
| law of their nature. Whatever stands in
| their path is Illuminated but nothing else
| They travel between walls OF darkness on
| both sides. Natures searchliGht is different
At a distance of ninety-three millions of
miles from the earth the sun has radiant
energy enough to annihilate darkness, and
projectile force enough to illuminate not
| only the planet on which we live, but sew
| eral others besides And still the question
| occurs, how is his light generated and trans
| mitted, and what is it?