The Columbia herald. [volume] (Columbia, Tenn.) 1850-1873, 1871-09-15
Alfred =. Horsley.
COLUMBIA, TENNESSEE, SEPTEMBER 49, 1871.

'SAcy. = --Ets4i .'- 4, -, ...t. i.
settle down, forcing up the lowe
strata. In descending It meets oant
mingles with the warm, moist ali
beneath, forming cloud. Whatever
latent heat may be evolved by CON
densation is at once reabsorbed by &C.
cessions of cold air from above. The
descending stream, fed by oblique trf.
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 q column Is drawn up
into it. The ascending column also
takes on gyradon, 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 commotion of the
great whirI 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 it rolling up from the
| south. In the mean time the des-
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 diffused as no longer to exhibit the
concentrated power Of the tornado.
The whirl becomes coextensive with
the overhanging cloud, and the me-
teOr is now rain or hail storm Of
tremendous violence. The tornado of
April, 1867, near Tuscaloosa, ragged as
such for about thirty miles, when it
lost its distinctive feature the spout,
and poured such torrents as to cause
great freshet in the Warrior River,
1t has already been stated that the
Natchez tornado expended itself In q
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 of southern winds. AS
the sun advances north, after the
winter solstice, the south winds that
reach US blow from latitudes 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 q
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 this is 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 a uniform tempera-
ture, over a wide extent, is impOssi-
BILE, from tie 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 vio-
lence of storms produced by descend
ing air is not difficult to comprehend.
When downward column becomes
well 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 q great ocean of air superimpos-
ed upon another abnOrmally elevated
in temperature, and therefore abnor-
rarefied. The tornado is 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.
ION the other hand, when the trans
position begins in consequence OF the
Of a definite column, as
from below, the earth's sur.
face presents limit, and the tributa-
ries cannot, as in the other case, flow
In straight lines without
leaving q 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
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-
lize 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
the central line of progression, for
then the blow Is delivered by the
front and rear of the rim, gyrating at
right angles with the row, and every
house must stand or fail, according to
it's own power of resistance. Or, if
firmly built house Withstand the out
ward shock, it may yield to the elas-
tic force of its inclOsed air, expanding,
as 1t must, with sudden and power
full effect, the instant the vortex,
which is partial vacuum, passes over
It.
"Again, pointed pieces of wood or
iron pierce or penetrate wherever they
strike foremost, and pebbles are i'm
beded i'm soft wood by the force Of the
blast. This is not so remarkable
when we reflect that the velocity of
yyration Is three hundred feet Sec
Dnd-aud 1t may go far beyond that
which is greater than the speed Of an
arrow shot from bow. On the track
Of the Pickens County tornado rafter
Of a house was driven through a pine
tree"
Dro1ouOAi Ti~fIa