Wichita eagle. [volume] (Wichita, Kan.) 1886-1890, 1889-11-26
LITTLE DROPS OF DEW.
TIE TRUE THEORY OF THEIR ORR
GIN AND OTHER FACTS.

Curious Phenomena They Exhibit and Err
roneous Ideas Concerning Them-Won-
derfnl Productions of Nature That Puz-
zled the Ancient Philosophers.
To the ancient philosophers the appearance
of dew and frost was O complete mystery, and
numerous were the theories advanced, by
those scientifically inclined, to account for
their production, and the interesting phe-
nomena they presented. Many, it is said, be-
lieved that the dew was nothing else than the
tears shed by the Almighty upon our earth,
and they regarded it as a sacred substance
that possessed number Of wonderful and in
applicable properties. They also attributed
TO it many strange events and curious mani
festations that occurred in those times, and
some rubbed it over their bodies in order to
protect themselves from the evil spirit, whose
malignant influence was held responsible for
all the marvellous and unaccountable opera
tions of nature observed in the earth and the
heavens above.
STRANGER THAN FICTION.
Among all the numerous truths stranger
than fiction" that the study of natural sci
ence has revealed, there are few more inter-
esting and instructive than those relating to
the phenomena Of dew and frost.
The late Professor J. Dornan Steele in his
excellent work, Fourteen Weeks in Physics, !"
says: Dew was anciently thought to possess
many wonderful properties Baths in this
precious liquid were said to conduce greatly
to beauty. 1t was collected for this purpose,
and for the use of the alchemsts In their
weird experiments, by spreading feeces of
tpn 7 ,,hi
pher OF the middle ages, claimed that dew
was ethereal, so that if we should fill lark's
egg with it and lay it out in the sun, imne-
diately on the rising Of that lunainary, the
egg would fly off into the airI This expert
ment is best performed with goose's egg"
There is considerable Misrepresentation
among the general public concerning the ma
ture and origin OF dew and frost, it being
commonly supposed by the great majority of
people that dew actually falls from the sky,
and how frequently do We hear the ex-
preston 1.-The dew is falling fast" The fact
is, dew never falls. but is formed on the sur
face of the earth, and always at the identical
place where it is seen by the observer. Dew
is simply the moisture of the air condensed by
coming in contact with objects upon the
ground that ara colder than itself. The earth,
heated during the day by the suns rays at
night Goods OFF and raGiates considerable
portion of its heat into space. All bodies left
to themselves, will gradually become cool if
previously heated. This is termed in natural
philosophy, radiation, and it. may be easily
demonstrated by experiment. Take an iron
ball for instance, heat it to incandescence or
until it becomes ''red hot" and then suspend
it by wire. In a little while it will part
with all its heat, and feel quite cold to the
touch. The heat has been thrown of, as it
were, or radiated, and not carried away by
the surrounding air, for precisely the same
effect will be produced if this experiment be
perfected in vacuum. Our earth is con-
stant1y radiating its hest, like the imaginary
ball, in all directions, and at night becomes
so cool that the invisible vapor resting
upon its surface is condensed into water
and deposited as dew" The temperature at
which this takes place is called the "dew
point" as indicated by an accurate and reli-
able thermometer But this point is by no
means constant or invariable, since dew is de-
posted only when the air is saturated with
vapor, and the amount of moisture required
to saturate air of high temperature is much
greater than for air CT low temperature.
LIKE THE SWEATING" PITCHER
All bodies have not the same capacity fol
radiating heat, but some cool much more rap
idly than others. Hence, with the same ex
posture, some bodies will be covered densely
with dew, while others will remain perfectly
dry. Dark objects have more dew deposited
upon them than light ones, because they are
better radiators, and, therefore, part with
larger amount of heat. This fact may also
De demonstrated by placing a black wooden
cloth and a white linen or cotton one upon
the ground over night. Grass, the leaves of
trees, wood, etc, radiate heat very freely;
but polished metals, smooth stones and cotton
cloth part with their heat more slowly, SO
that the former OF these substances will be
completely drenched with dew, while the lat
ter, in the same situation, will be compare
lively dry.
The amount Of dew formed on any night is
greatly Influenced by the condition of the at
mosphere. More dew is formed on clear even
ings than when the SKY is obscUred by clouds,
because they act as shield, and reflect back
the heat rsdiated by the earth into space, be-
sides furnishing that received by them dur
ing the day, which prevents the earth from
cooling off enough to produce large deposit
of dew. But when the sky is free from clouds
the earth radiates larger amount of heat,
there is nothing to intercept that thrown
off from its surface This is the reason why
we always have colder nights when no clouds
obscure the SKY.
The formation Of dew is prevented by a
strong breeze, which removes the layers OF
moisture resting upon the ground before they
have time to cool down to the dew point"
4 Slight breeze, however, is favorable to the
production of dew, as it replaces the layer of
air from which water has been deposited by
another containing more moisture. No dew /
may ever be expected when the sky is OBJ |
scured by clouds, or when there is a strong |
wind
The moisture that appears upon the outside |
Of pitcher when it contains very Geld water |
is nothing but dew, and is produced by the |
same cause explained above. This dampness |
frequently observed upon a cold pitcher, |
even during the hottest weather in summer, |
Is commonly referred TO by saying 1.-The |
pitcher is sweating" anu IN this simple illus
tration We are permitted 10 recognize before /
our eyes, on small scale. the same interest /
ing process OF dew formation that takes place /
over the surface OF the great earth Dew is
alluded 10 in the writings Of many ancient |
philosophers, and the Bible contains = quaint I.
passage in regard to Gideon's fleece tSee
Judges vi. 57-0.l-A- K. Bartlett IN Detroit
Free Press
SOME AUTHORS FULL NAMES.
Bayard Taylor's first name was James
Bret Harte's baptisnal name is Francis Bret