The times-herald. [volume] (Burns, Harney County, Or.) 1896-1929, 1914-08-15
LIGHT OF THE sun
In Its Pure State We on the Earth
Have Never Seen It.
SOME RAYS DO NOT REACH US.
n They Did They Would Probably De-
strey Life 40 II Esists on Our Planet
Daylight and Sunlight Differ Almost
as Much 90 Do Wine and Water.

payiloht and Sunlight Differ Almost
as Much 90 Do Wine and Water.
"As clear as daylight" expresses In
ordinary language maximum OF plain
ness and obvlousness Nevertheless
daylight is cue Of the most complicat-
ed and capriciously variable Of all nat
ural phenomena.
Almost everybody you meet viii tell
you that daylight and sunlight are DIFF
ferent names for the same thing. They
think they know that much OF astron-
omy anyway. but astronomy does not
teach anything OF the kind. Astronomy
simply tells US that the sun is the pri-
mary cause or source Of daylight, but
st does not say that daylight and sun
light are identical. In fact, they diff
fer almost as much us do water aud
wine.
But the degree OF difference varies.
Daylight is a mixture Of two kinds OF
light, and Its quality is continually
changing, as everybody who has ever
had anything to do with photography
knows. The proportions OF the two
kiads OF light that make daylight are
not the same from hour to hour aud
hardly from minute to minute.
In clear weather. under an open sky,
with the sun high In the heavens, day
Hight, says Professor Nichols OF Cor
nell, Is almost entirely sunlight. A
white surface exposed to an unobscur-
ed sky receives directly from the sun
50 per cent Of the light that illuminates
Il and only IS per cent from other
parts of the sky dome.
This other part OF the illumination
is called skyllght. and It consists OF
light. nearly all Of which came orig
inally from the sun. but which has
been changed In quality by reflection
from the earth. from the clouds and
from dust and vapor In the air. Many
OF the rays that characterized the orig
inal sunlight have been absorbed by
the rejecting substances. so that what
remains Is no longer the same thing
as before.
On a completely overcast day there
is no sunlight, properly so called. but
OniI lhkhh w NhNthGh NhG ohy -
overcast or not the intensity OF day
light varies with the hour OF the day
and with the season. This Is due to
differences In the elevation OF the sun.
These variations IN the intensity OF
daylight are surprisingly great. The
intensity Is on the average ten times
as great in midsummer as In mldwin.
AaH hnk from
expressing the utmost difference that
can exist, for investigation has shown
that between the clearest summer day |
and the darkest day OF winter the ra-
tio Of the intensity OF daylight may be |
as great as 800 to !.
Besides, the quality OF daylight IL
changing on account OF the
tho different rays of the spectrum that
are mingled In It. The spectrum OF
light Is a gamut of vibrations, and the
result of the selectlve action exercised
by the substances aud vapors. from
which the light has been reflected and
through which II has passed Is to pro
duce variations Of color and OF intensi-
Va tSttAs 10 WC&i 10 VA thC |
of invisible radiations present. aud
these variations are not the less real
md important because the eye Is not
always fully aware OF them.
As to pure sunlight, we never see II
IN the earth. The light that arrives to
10 from the sun has neither the color
Tor the intensity that II possesses be-
'ore II enters the atmosphere. The
Ultraviolet rays especially are almost
completely screened OF by the atmos.
here. and II they reached US In their
ull force It is probable that life as
low organized on this planet would be
destroyed by them.
Every different world has its own
laylight, although all may be illumi-
ated by the same sun. Not only does
elative distance affect the intensity OF ,
aylight on different planets. but the
OF their various atmos- I
heres has an equally great effect. J
'eDus has daylight twice as Intense !
$ ours; Mars half as intense. On i,
upiter the intensity is 1-25 OF that on :
be earth; on Saturn. 100; on Nep- :
Inc. 1000.
But each Of these planets has an at =
losphere peculiar to itself, and thus 7
,e differences OF daylight upon them
re made still more remarkable. This !,
one Of the first things to be taken =
ito account In all speculations about a
,e habitabllity OF those other worlds. :,
Garrett =. Servlss In Spokane spokes- =
an-Revlew. y