The Harrison times. (Harrison, Boone Co., Ark) 1876-1938, 1886-08-07

both the light and heat of the sun
pass unimpeded through glass, ar
tiiicial heat is intercepted by this
transparent medium, 1t is n little
strange that the heart of an ordin-
any fire should pass freely through
u layer of rock salt when it is UNI
able to penetrate pane of common
glass; and it il worth observing
that while the hot rays of the sun
pass through glass with such per
feet freedom, they cannot find their
way back by the Same channel.
The warmth once enclosed i'll q
hot-house, cannot escape by the
process that allowed il to enter
the building; it must first heat the
glass panes in the roof, as it would
any other substance, in order to
get out again.
At first thought it is difficult to
see why the rays of the sun should
pass through the atmosphere
without heating it all; and yet, if it
were not so. the temperature on
the top of Mount Blanc would be
higher than it is in the valley of
of Chamounix. But is still more
extraordinary that the rays of the
sun should pass through a cake of
ice without melting it all, as is the
case when the thermometer
stands little above zero. That
the rays of heat actually penetrate
the ice is shown by the fact that a
lens of ice may be used for setting
fire to inhammable substances.
If it were possible for us to rise
above the atmosphere which sur
rounds the earth, we should see
nothing but an intense and sharp
ly-defned ball of fire, while every
thing else would be wrapped in
total dark ness. There could be
no diffusion of light without an
atmosphere, or some similar medi-
UNI for it to act upon; but if the
air about us extended to height
of 700 miles. the rays of the sun
could not penetrate it, and we
should be left in darkness. AT the
depth of 700 feet in the ocean, light
ceases altogether one half of it
being absorbed in passing through
only seven feet of the purest wa
ter.
Light itself is colorless, and
therefore, strictly speaking, 1t
is never seen. The process by
which it makes objects visible,
when it falls upon them, 10 very in
teresting and wonderful, and yet
it is matter about which COM
paritively few persons ever con-
Germ themselves. Why is that in
room in which evely thing was
absolutely destitute of color 80
long as the .hutters were closed,
the moment that the sunlight is
introduced we see such Varieties
of crimsons and greens and browns
and yellows, elaborate patterns on
the walls and carpeted floors and
draperies and pictures of every
shade and hue? Chat is simple
} enough" you may replys when
the room was dark of course there
was nothing to be seen; but rs
aoon Us it is light, everything be-
comes visible, and each in its own
special color" But why is one
thing red and another blue?
This red had no redress
about it when the room was
dark it was absolutely without
any color at all. 1t had
nothing more or less but a capaci-
ty for redness, and that capacity
was determined by the singular
fact that when the suns rays fell
upon the curtain it at once alb
sorbed all but the red rays, and
if these were excluded from enter
ing the room, while all the other
rays were allowed admittance,
there would not be red thing to
be seen. Why it is that certain
substances absorb one set of colore
and other substances another sort
nobody can tell.
1t seems to be very common
place thing to say that the light