The home journal. (Winchester, Tenn.) 1858-188?, 1871-09-21
decrease in diameter, and therefore in

decrease in diameter, and therefore IN
circumference, as We go toward the
poles ofthe earth. Ashley all revolvc
In twenty-four hours, 1t follows that
every one, approaching the pole Oh
either side Of the equator, moves
around more slowly than the one
preceding 1t. Therefore, current
moving southwark, to the vortex of a
tornado in the northern hemisphere,
finds that vortex rotating eastward
| with superior velocity, and Is left
behind, or projected to the west, while,
for the same reason, o current blowing
northward to the vortex finds Its rOta-
ton with inferior velocity, and pre-
serving Its own easterly momentum,
Is hurled forward or projected to the
east. Thus the south half of the rim
being impelled eastward, and the
north half westward, the backward or
left-handed gyration is fixed and
maintained. Just the reverse Is true
in the southern hemisphere Of the
earth, while on the equator the gyra-
ton would be free to take either di-
rection.
"The process OF formation is easily
cOmprehended. In All atmosphere
supersaturated and unduly heated at
the surface, let calm prevail over
many miles OF territory. The equili-
brium Is powerfully disturbed. A
great volume OF elevated air begins to
settle down, forcing up the lower
strata. In descending 1t meets and
mingles with the warm, moist air
beneath, forming cloud. Whatever
latent heat may be evolved by con.
densatlon Is at once reabsorbed by ac-
cessions Of cold air from above. The
descending stream, fed by oblique tri-
butaries from all points of the COM
pass, begins to gyrate. From centri-
fugal force result rarefactiOn, cooling
and further condensation. The CEN
ter Of the vortex Is partial vacuum,
and from below column is drawn up
into 1t. The ascending column also
takes on gyration, and the tornado
spout Is created. But this spout, the
effect Of which is so terrific, is never
theless secondary and Incompatible
to the tremendous cOmmotlon of the
great whirl above. The two columns
meeting, vast volumes OF air are
thrown of by centrifugal force in all
directions, and the cloud expands and
enlarges with amazing rapidity. This
expansion Is often mistaken for pro-
gression OF the storm; the cloud ap-
pearing to approach one observer
from the northwest, perhaps, while
another sees 1t rolling up from the
south. In the mean time the dcs-
cending stream has pressed the cloud
down upon the surface, where 1t en-
velops everything along Its path in
almost total darkness. At length the
superior vortex becomes so great in
diameter that the spout is disrupted, or
so difiused as no longer to exhibit the
concentrated power Of the tornado.
The whirl becomes coeXtcnsive with
the overhanging cloud, and the me-
teOr Is now o rain or hail storm Of
tremendous violence. The tornado OF
April, 1867, near Tuscaloosa, ragged rs
such for about thirty miles, when 1t
lost Its distinctive feature the spout,
and poured such torrents as to cause
q great freshet in tho Warrior River
1t has already been stated that the
Natchez tornado expended Itself in u
tremendous rainfall, and this is the
termination Of all these storms.
"The tornado may be looked for In
the winter and spring months, during
the prevalence ofsouthern winds. AS
the sun advances north, after the
winter solstice, the south winds that
reach us blow from latitudcs on the
Gulf. They have then, not only
abundant moisture, but tempera-
ture higher than Is due, at any time
before June, to the effect Of the solar
rays in our own latitude and therefore
answer the necessary condition Of a
stratum heated uniformly over large
area. Our tornadOes consequently do
not grow out Of the heat rays that
penetrate our latitude, but rather from
the heat Of the tropics, transported
hither in the winds; and tbisls the rea-
son of their appearance either in the
daytime or night. We never witness
them in the hot summer, because then
the lower atmosphere Is warmed by
direct rays, and uniform tempcra-
ture, over wide extent, Is impossi-
BILE, from the fact that the cleared
lands and forests, hills and valleys,
are heated unequally, giving rise to
ascending columns and moderate
storms. The cause Of the greater vic.
lence OF storms produced by descend
Ing air is not difficult to comprehend.
When q downward column becomes
we'll defined, it Is fed, as before sug-
gested, by tributaries flowing oblique-
" down from all sides. The very top
Of the atmosphere sinks freely into
the stream. The case Is precisely
that of q heavy body descending an in
clined plane; but the heavy body is
here o great ocean of air superimpOs-
ed upon another abnormally elevated
in temperature, and therefore abnor-
mally rarefed. The tornado is q pro-
cess which the one seeks to settle be-
meath the other, and Is not unlike
what would occur should an opening
be made through the bottom of some
great reservoir of water.
"On the other hand, when the trans
position begins In consequence Of the
movement of q definite column, as
cending from below, the earth's sur.
face presents limit, and the tributa-
ries cannot, as in the other case, flow
obliquely In straight lines without
leaving o vacuum beneath, and that
Is impossible. They must, therefore,
though ever seeking to mount up
ward, still trail along the surface un-
til they converge at the center. An
impediment Of this nature would find
adjustment in many uprising columns
of limited power, capped with cumuli
and resulting in showers, but no ono !
vast, absorbing vortex, could monopo-
lie the whole movement, and shake
the armament with Its might.
1.-THE effects Of the tornado are often
TO all appearances, very anomalous
and extraordinary. 1t strips the
feathers entirely from fowls when the
gust strikes them behind. In q row
Of buildings in line with its direction
it may throw down the middle one
and leave the others standing. This
Is possible when they are located on
tha central line Of prOprpaaion f,,r