The mirror., 1919-04-24
PHENOMENA OF LIGHT
An Instructive Paper Dealing With That So Little Under
stood Physical Energy-Light
Read Before the Prison Chautauqua, by Il. K. s.

discovered. Today we have mod
ern instruments of great accuracy
which measure the velocity of
light. Yet the result is the same,
a little in excess of 1876, 900 miles
per second. Science accepts 1885,
$50 miles as correct.)
The planet Jupiter has several
moons or satellites which revolve
around the planet. One of these
moons is eclipsed by Jupiter every
forty eight and half hours. On
a certain day in each year as the
earth travels in it's orbit around
the sun we are at point directly
opposite Jupiter. The almanac
will tell us the day. With the tele-
scope we observe Jupiter and note
the exact time the eclipse takes
place. Six months later the earth
has travelled halfway around its
orbit. We are now exactly op-
posite the place where we made
our first observation. But a dis
tance of 1876, 900, 900 miles separ-
ates us from that place. since the
orbit of the earth has diameter of
1856, 900, 900 miles. We now note
the time the eclipse of Jupiter and
his satellite takes place and find it
to be just Is minutes and 38 Sec
onds later than it occurred at our
first observation. This gives us a
simple problem in arithmetic, and
the solution of the problem shows
us that light travels approximately
10000 miles in one second of
time.
The word reflect means to
throw back. When the light waves
strike an object some of them are
reflected and render the object
visible. Others are absorbed by
the object and this gives color to
the object. The word absorb"
means to suck in. The amount of
reflection and absorption depends
upon the nature of the object. Re-
Election and absorption of light
causes the color of all objects. and
l wish to emphasize the fact that
color is not a property of matter
but of light. Thus, an object that
reflects nearly all the light it re-
ceives would be white. An object
which absorbs nearly all it's light
would be black. A flower would
be red in color if it absorbed all
the light but the red light. This
it reflects to the eye, causing US to
see the flower as red in color. The
color does not belong to the flower
but to the light. The matter of
colored light will be more fully
dealt with in our description of the
spectrum. In case an object is
highly polished it not only reflects
most of the light it receives but
also causes an appearance of an
image of the object reflected. If
the reflection occurs upon a plane
surface then it gives an erect
image of the object. but the image
appears to be formed as far behind
the rejecting surface as the object
is before it. The image likewise
undergoes another change called
lateral inversion, being reversed
from right to left.
The word s'refract" means to
bend. and refraction of light is
that change which takes place in
the direction of light rays when
they pass obliquely from one trans.
parent medium into another ot
different density. We have all
witnessed the following simple
phenomenon:
A long. straight stick stuck into
a barrel filled with water and
viewed from one side appears to
be bent or broken where it extends
beneath the surface of the water;
likewise a fishline suspended from
a pole in still water. The line
hangs straight from the end of the
pole to the surface of the water.