The southern sentinel. (Winnfield, La.) 1883-1910, 1885-05-08

This is especially true If the Their
mometers are at different levels and
there is no wind. We treat of air I'M
der the head of pneumatics, whereas it
sometimes comes rather under the
head OF hydraulics, for cold air foes IN
currents the same Is fluids. In the abb
sence of wind which mixes up the
strata of air of different temperatures,
and consequently of different specific
gravity, the cold air of the night will
flow in streams and gather in ponds or
lakes the same as water. Under such
circumstances the temperature will
vary with the level, and the subject OF
thermal levels becomes matter OF i'm
portance. l have made many observa-
tons to determine the difference OF
temperature with slight differences OF
elevation. An open air thermometer
hangs at the north door of my labora-
tory, adjusted to avoid accidental va
riations of temperature. Aravine runs
through the college lawn near the lab
oratory. A thermometer was placed
in he ravine $50 feet from the one by
the laboratory door and twenty-five
feet below its level. In very cold
weather, when the air was very still. |
have occasionally seen the thermome-
ter in the ravine mark eight degrees
below the thermometer at laboratory
door.
During the cold weather of last
month I again examined the relative
temperature at these two points, select
| ing mornings W tn little wind for such
observations and reached the following
results:
February D, at e:45 a. m. laboratory. .-15o
February -, q As a. m, ravine.
February 3, at $50 a. m, laboratory....-i5SS
February q, at $50 a. m, ravine
A slight breeze with velocity of two
miles an hour was blowing on both
mornings. The lowest temperature on
the preceding nights at my meteorO-
logical station (about forty rods dis
tant and on higher ground than the
laboratory was IA deg.
February "a, at $50 a. m, laboratory....-1o
February "A, at $50. a. m. ravine.
I then carried the thermometer from
the ravine and hung it by the side Of
the one at the laboratory, and they
soon marked the same temperature
1 deg. I carried the thermometer
("Green's Standard'') back to the
ravine and placed it about two feet
lower, and in the narrow channel of
the ravine, and it soon reached deg.
The minimum temperature at my sta
ton for the night was deg.
These Investigations show that Their
NAL levels, or marked changes of tenn
perature with slight differences of
elevation, are facts of great import
ance to the farmer and fruit-grower
where the difference of few degrees
of temperature makes the difference
between success and failure. A very
intelligent fruit-grower in the Traverse
region had on his farm a long narrow
valley of sandy soil which descended
somewhat rapidly into another deeper
valley below; about half way down
this upper valley was bank or dam of
sand cutting across the valley like a
mill dam across stream. The soil being
a warm quick sand was cultivated, and
good crops secured save in the air pond
| above the dam. No frost troubled the
crops in other parts of the valley. Tir-
ing of this dam and weary of thefrosts
he removed the dam and opened up
the valley for its full length. He had
| no more frosts in his former frost pond,
the aerial torrent now left its frost
marks in the lower part of the valley,
where the crops had never been
troubled before the dam was re-
moved. Aerial drainage is subject
that will demand more attention in
the future. Kedzie, in N. Y.
Tribune.