Evening star. [volume] (Washington, D.C.) 1854-1972, 1903-10-31
THE AZURE SKY.
Scientific and Artistic Interest Attach
ing to This Color.


From the Scientific American. .. - t...--
Every one notices the blue color of the
sky. 1t has grown familiar to us by daily
observation from childhood, yet few per-
sons realize the great scientific and ar
tistic interest attaching to this beautiful
color.
Sir Isaac Newton tried to explain the
color in the year 1875 by referring 1t to
the blue colors seen in thin soap bubbles
used in his experiments He thought the
air above our 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 armament.
Sir John Herschel explained the color
of the sky by Newton's theory, but later
writer's have proved that In some lmpor-
tant respects his theory was wrong.
In 1863 Prof. John Tyndall, the famous
British physicist, found that he could
produce SKY blue" by experiments 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 Or
binary density mixed with nitrate of
butyle vapor, which Is extremely volatile
powerful beam of electric light in a room
otherwise dark the mixture precipitated
a beautiful blue cloud. which in color ri
vailed the finest Italian sky. Further ex-
at last discovered the secret Of the blue
color of the sky, which had puzzled the
greatest philosophers Of all ages
Lord Rayleigh. the famous professor OF
exnerimental physics at Cambridge, Eng
land, and one Of King Edwards original
twelve members of the new Order of
Merit, has Investigated Tyndalrs theory
of the color OF the SKY by profound
many years. He confirms Tyndalfs theory
that the blue arises from the reflection
Of the suns light 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 at
mosphere, and by rejecting the blue part
of the SUMS light give the dome OF the
heavens blush tint. -
Some Of the particles are water. but
most Of them are composer of the oxygen
and nitrogen which we breathe.
Prof T. J. j. See s0f 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 valley. Bis conclusion Is that
the beautiful red e9lors OF. sunsets and
sunrises SO much spoken Of by Greek and
Roman writ6sA andcso often illustrated
in landscape painting arise from water
vapor in the Tower layers of our atmos-
phere, absorbing the blue and transmit
ting the red light according to DR.. See
our air within five miles Of the earth's
surface, while the deep blue Of the sky
arises from reflections Of minute 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 sunset show that the
red arises near the earth, while the blue
has its seat very high up. Above our at
mosphere the sky has all the blackness
of the darkest night.
Prof See has watched the duration of
the blue sky after dark and found 1t to
continue for about an hour and fifteen
minutes, and from this he shows that our
atmosphere extends to a height of fully
1870 miles, Astronomers have usually
found the height Of the atmosphere by
computing the height of meteors, but
none ever made the height of the atmos-
phere over 100 miles.
The study of the blue color of the sky
thus proves also that our atmosphere ex-
tends considerably higher than scientists
have heretofore supposed.
On>our dark days the blue color OF the
sky is shut out by clouds, and combina-
tions of colOrs due to rejecting clouds
and countless myriads of particles in the
ethereal regions high above the earth
give the bright light which Is so much
relished in daily life. The nature of the
blue sky so much admired by all man
kind since the days of Homer ana Job.