The Savannah morning news., 1901-08-27
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RAINFALL AND COMFORT.
Atmosphere May Be TOO Dry or Too
Moist for Health.


From the London (Ontario) Advertiser.
Few natural phenomena are of great
er practical importance than rainfall
and evaporation. They concern closely
both our health and our personal COM
fort An arid condition of air on earth
Is highly annoying and injurious. Air
Tar below saturation point has an in
furious effect upon the skin, which it
dries, roughens and cracks, while dur
ing the winter the body heat is too rap
idly distracted, causing a sensation of
chilliness, II no more severe symptoms
or cold. Air nearly or quite saturated
is equally unpleasant during the sum
mer season. The perspiration instead
OF being conveyed away in the form of
Napor from the body as rapidly as it
is secreted, stands in beads upon the
skin, and the body heat deprived of its
chief outlet and source of loss-the lat
ent heat of poration-accumulates
and causes discomfort.
Besides these, a dust-laden air or a.
Undiscovered earth may be mentioned
as real inconvenience. But of more
vital concern is the unfavorable effect
upon plant development which a water
saturated soil has.
proper balancing of rainfall and
evaporation is essential to our COM
forta BILE existence upon earth When
active condensation has set in, the wa
ter vapor furnishes a welcome shade
from over-ferce solar rays, and al
ways water vapor in the air checks
the loss of heat from the earth's sur
face. In higher realms of our compo-
site nature the phenomena connected
with evaporation and condensation of
water rouseS the reasoning and the
imagining capabilities of our being We
naturally inquire what is evaporation?
What are the forces producing this
change? What are its effects? The I'M
romantic dweller on lowland plains
may see on his horizon splendid noun
tain submits, and Cordilleran ranges
represented in cloudland by billowy
masses of minute water drops.
Phenomena of Evanoraffon.
The nature of the phenomena occur
ring during evaporation, concerning
as they do the ultimate molecules of
which the substance is composed can
not be easily understood. One theory
is that the molecules of a liquid move
on the average more slowly than those
of its corresponding vapor. but that
some molecules move more rapidly
than others, and these rapidly moving
particles are constantly escaping from
the liquid to lead for a time a free ex-
istence in the gaseous state. There are
objections to this theory, one being
that most fluids will entirely evaporate,
and it does not appear how under GER
tain circumstances the speed of the
motion of their particles is increased.
Neither does the theory explain why
evaporation is more rapid under de-
creased pressure. Late experiments
seem to point to the conclusion that all
bodies are giving off streams of par
ticles much smaller than atoms would
appear to be. If this be the case when
water evaporates ii is interesting to
imagine under what conditions and i'm
PEELED by what forces they again unite
and reform liquid. Heat undoubted-
ly has something to do with the pro-
cess. but other molecular forces are
probably acting In conjunction TO pro-
duce the phenomena of evaporation.
In the case of our three upper lakes
Superior, Huron and Michigan-the wa
ter surface is $1,000 square miles. the
area of land draining into them 100000
square miles. In the Caspian basin the
ratio of water to land is l to 4, and
the balance OF rainfall and evapora-
ton is being maintained without any
discharge. Would IT not also be MAIN
tanned in the Great Lakes basin with
one Square mile OF water to two square
miles of land area draining into it UNI
der like conditions? 1t would appear
almost certain that vast subterranean
rivers must find their way into the
lakes from outside their BASIN In
most places throughout the Mississippi
valley underground lakes and streams
are known TO exist, and have been
struck in sinking wells. In Montana
wells often flow with high pressures.
Temperature of Lake Water.
The temperature of the water in the
lake is to low and its color too clear to
suggest that much of il had it's origin
in northern peat boys. The Mediterra-
mean waters vary in temperature from
go degrees Fahrenheit on the surface
to So degrees Fahrenheit in the deeper
portions during the hottest parts of
the year. The Mediterranean in deep
est parts is four times as deep as our
upper lakes. The water in our lakes
is much colder in proportion TO that
of the Mediterranean. Lake Superior
water Is icy cold at all times and Lakes
Michigan and Huron are but few de-
grees warmer. The temperature sug-
gests supplies drawn from far-off
sources and conveyed in subterranean
channels.
The Missouri river loses one-haif its
water while passing around the Great
Bend, in North Dakota. Other large
streams in the western country lost
much of their volume in passing over
| the porous cretaceous strata, and this
probably gives rise to the vast system