The Black Hills union. [volume] (Rapid City, Pennington County, Dakota [S.D.]) 1889-1904, 1903-12-04
REASONS Why SKY
is or Azure TINT
-
Different Scientists Have Ad-
vancGd Different Reasons
to Explain 1t.
~rYNDALL'S EXPERIMENTS
"Sky Bluc' Produced in Laboratory
Experimentation Caused by
Reflection of Sunlight From
Particles in Air.

Scientific American: Every one no
tees the blue color of the sky.
has grown familiar to us by daily ob.
servation from childhood, yet few per-
sons realize the great scientific and ar
tistic interest attaching to this beau
tiful color.
Sir Isaac Newton tried to explain the
color in the year 1876 by referring it to
the blue colors seen in hin soap hub
bles used in his experiments. He
thought the air above u heads was
filed with small particles Of water.
which reflect the blue portion of the
suns light falling upon our earth, and
thus produce the blue tints Of the fir
mament.
Sir John Herschel explained the col
or of the sky by Newton's theory, but
later writer's have proved that in some
important respects his theory was
wrong.
In 1869 Professor John Tyndall, the
famous British physicist, found that he
could produce "sky blue" by expert
ments in the laboratory.
For this purpose he filled a glass
tube about a yard long and three inches
in diameter with air of one-tenth the
ordinary density mixed with nitrate of
butyle vapor, which is extremely Vola-
tile. Then on passing through the
mixture a powerful beam Of electric
light in a room otherwise dark the
mixture ~precipitated a beautiful blue
cloud, which in color rivaled the finest
Italian sky Further experiments
proved to Tyndall that he had at last
of the sky, which has puzzled the
greatest philosophers Of all ages.
Lord Rayleigh, the famous professor
of experimental physics at Cambridge,
Eng, and one of King Edwards orig
tnal twelve members Of the new Order
of Merit, has investigated Tyndalps
theory of the color of the sky by pro-
found mathematical researches extend-
ing over many years. He confirms
TyndalTs theory that the blue arises
from small particles in the air less
than one hundred thousandth Of an
inch in diameter. Billions and tril-
lions OF these atomic particles fill the
atmosphere, and by rejecting the blue
part of the suns light give the dome
of the heavens a blush tint.
What the Particles Are.
Some of the particles are water, but
most Of them are composed of the oXy-
gen and nitrogen which we breathe.
Professor r. j.. ]. See of the United
States navy is one of the American
scientists who have studied the subject
in another aspect. He has observed the
color of the sky in various attitudes in
high mountains and in dry and moist
countries, such as Egypt and Greece
and Arizona and the Mississippi val
ley. His conclusion is that the beauti-
full red colors of sunsets and sunrises
SO much spoken of by Greek and Rom
an writer's and SO often illustrated in
landscape painting arise from water
vapor in the lower layers Of our atmos-
phere, absorbing the blue and rams
hitting the red light. According to DR..
See the reddish colors come from that
part of our air within five miles of the
earth's surface, while the deep blue of
the sky arises from reflections of mi
mute particles in the higher parts Of our
atmosphere. The water vapor does not
extend very high, clouds never rising
higher than ten miles above the earth.
The blue streaks cast by clouds at sun
set show that the red arises near the
earth, While the blue has it's seat very
high up. Above our atmosphere the sky
has all the blackness Of the darkest
night.
Professor See has watched the dura-
ton Of the blue sky after dark and
found it to continue for about an hour
and fifteen minutes, n from this he
shows tina our atmosphere extends tc
a height of fully 1870 miles. Astronom
ers have usually found the height OF
the atmosphere by computing the
height of meteors, but none ever made
the height OF the atmosphere over 10(
miles.
The study Of the blue color Of the sky
thus proves also that our atmosphere
extends considerably higher har
scientists have heretofore supposed.
On our dark days the blue color Of the
sky is shut out by clouds, n combi'
nations of colors due to rehectingc cloud:
and countless myriadS of particles II
the ethereal regionshigh above the artt
give the bright light which is SO much
relished in daily life. The nature o
the, blue sky so much admired by al
mankind since the days Of Homer ant
Job, now fully explained by modern
science, still preserves its ancien
beauty and will inspire mans mint
through coming ages.