St. Tammany farmer. [volume] (Covington, La.) 1874-current, 1889-06-29
WONDERS OF SCIENCE.
6tatoments Which Read Almost
Like . Fairy Tale.


To many the teaching OF science
within the last few years is as inter-
esting, il not Is startling. as were
Grimm's fairy tales to our youthful
fancy. Time-honored notions and re-
vered fctions. around which the hal
lowed associations of our early scien-
tific training fondly and firmly cling.
are being weighed in the balance; and
with reluctance we have to part with
them. The freshness of the stories Of
scientific research is only equaled by
their b0ldness. Yet. when grasped by
a clear mind open to accurate instruc-
ton, the new theories are fascinating
In their grandeur and comprehensive
ness; and whether We wander in the
painless woods or by the lonely shore
we can rapturously nourish not only
our youth sublime but our maturer
age, with the fairy tales OF science.
and the long results of time"
Some of these beautiful stories we
will glance at in this paper; but little
more than the contents can be given in
the space allowed to us. One OF the
most interesting of the tales is on the
formation Of der. Until very recent
" fairy-like charm was attached
to this beautiful phenomenon. for
the poet described the ORR
emit dew rs ''shed from the
bosom of the morn into the glowing
roses" But no longer can it be truly
said that on any sweet spot ''early fa's
the dew;" though the tender song will
not suffer by the altered Interpretation
of science. For it is now held by the
best physicists that instead of falling
from above, the dew rises from the
earth. The generally received opin-
ion that the dew is formed OF vapor
existing at the time in the atmosphere
must be given up for the established
fact, that the vapOr which rises from
the heated earth is trapped by the cold
surface-earth. Besides. when We i'm.
agine that, on a cool evening after a
sultry day in summer. our feet are be-
ing wet by the dew on the grass. we
make q grave mistake. For that
moisture on the grass is not new at all;
it is false dew-in reality the transpired
humor of the plants. The drops ut the
tips, which glisten diamond-like. arc
not dew; close examination shows that
the crystalline spheres are all situated
Mt the points where the veins of the
leaves cut the outer edges. These
drops only give evidence of the vitality
of the plant The difference between
the true dew on the grass and the
exuded drops through the veins from
within the grass can be easily distin.
guished; for the former is distributed
all over the blade in a moist film;
whereas the latter are of some size.
and are situated near the tips OF the
blade.
So important is the part played by
dust in the phenomena of nature that
without it there ewould be no fogs.
no mist, no clouds. no rain at all.
Particles of water-vapor do not CON-
bine with each other to form a cloud
particle. Before such q combination
is possible it is essential to have some
solid body on which the vapor par.
ticles are to condense. The particles
of dust, then. are the free-surfaces or
which the change takes place from
water-vapor to fog. When there is al
abundance of dust in the air and little
water-vapor is present. there is Al
over-production of dust-particles, and
the fog-particles are in consequence.
close packed. but light in form. ana
take the lighter appearance OF fog
If, therefore. dust is increased in the
air in fine particles. fogs are increased
But if the particles of dust are fewe
and larger. in proportion to the mole
cules of water-vapor. each particle
gets weighted. becomes visible. an
speedily falls in mist or rain. With
out dust however. every blade Q
grass and every branch of trees wOul'
be dripping with moisture; there woul
be no use then for umbrellas. but on
feet and lower clothing would be a
WAYS wet. Better is it for the house
keeper to bear without frettins the al
moving dust in her rooms, than to hav
the walls always running with mois
ure! Without dust there would be n
clouds to shield us from the sun
burning rays; yet if the suns heat
rs is prophesied by our best authorit
should diminish. nature may hav
the compromising decrease OF tn
quantity of atmospheric dust; so tina
with the less cloud. the suns heat ma
reach the earth through q less dens
medium. to compensate for the d
crease at the initial heat This fol