The novelty and originality of this theory will perhaps justify us in
dwelling a little longer on what observation has detected. The vortex
(and we are now speaking only of the central vortex) does not derange
every place alike, but _skips_ over large tracts of longitude in its
progress westward. We speak here of the immovable axis of the vortex as
in motion; in reality it is the rotation of the earth which brings every
meridian under its influence in some latitude once every twenty-four
hours. The centre of greatest derangement forms the nucleus, towards
which the surface currents, under certain restrictions, flow. The
strongest current will, however, usually be from the south, on account
of the inclination of the axis of the vortex to the surface of the
earth.[8] These currents continuing onwards by their vires inertiae,
according to the first law of motion, assist somewhat in conveying the
warm surface wind, loaded with moisture, into the region of cloud; and
the diminution of temperature causes the condensation of large masses of
vapor, according to Hutton's views; and the partial vacuum thus
produced, causes a still greater intermingling. But we have already
shown that this is not the sole cause, nor is it ever more than
partially accomplished. The ether of the lower atmosphere, and of the
crust of the earth, is disturbed, and rushes towards the rarefied axis
from the surface, and with the temperature of the surface, thus
conveying the surface atmosphere, in a measure, along with it. In the
upper regions, this ether (or electric fluid) cools down, or parts with
some of its heat, to the air of those regions, and, by its great
specific caloric, necessarily and unduly increases the temperature of
the air. This, by its expansion and ascension will cause a further
influx from below, until the upper atmosphere becomes loaded with vapor.
In twelve hours, at least, a reaction must take place, as that part of
the earth's surface is carried six or seven thousand miles from the
axis, where the ether is more dense. This in turn descends to the
surface, carrying with it the temperature of space, at least 60d below
zero; a great condensation must follow; local derangements of the
electric equilibrium in the centre of large clouds, when the
condensation is active, must now take place, while partially
nonconducting masses intervene, to prevent an instantaneous restoration
of the equilibrium, until the derangement is sufficient to cause the
necessary tension, when all obstacles are rent asunder, and the ether
issues forth, clothed in the power and sublimity of the lightning. It is
a fearfully-energetic fluid, and, when sufficiently disturbed, competent
to produce the most violent tornado, or the most destructive earthquake.
That these two phenomena have simultaneously occurred, seems well
authenticated; but the earthquake, of course, must be referred generally
to derangements of the electric equilibrium of the earth's interior, of
which at present we know but little.
The day or morning previous to the passage of the vortex, is frequently
very fine, calm, mild, and sleepy weather,--commonly called a weather
breeder. After the storm has fully matured, there is an approach of the
clouds to the surface, a reduction of the temperature above, and the
human body feels the change far more than is due to the fall of
temperature. This is owing to the cold ether requiring so much heat to
raise its temperature to that of surrounding bodies, or, in other words,
is due to its great specific caloric. In summer, this falling of the
upper layers in front of the storm is so apparent, that every part is
seen to expand under the eye by perspective,--swelling, and curling, and
writhing, like the surface of water or oil when just commenced boiling.
The wind now partakes of the motion of the external ether, and moves
with the storm eastward (in this latitude), or from N-E. to S-E., until
the action ceases.