The theory, as extended by Col. Reid, rests on a simple rotation around
a progressing centre, and is found sometimes supported by evidence of
the most violent action at the centre, and sometimes by showing that the
central portion is often in a state of calm. We do not attempt to
reconcile these views; but would merely observe, that an atmospheric
vortex must be subject to the same dynamical laws as all other vortices;
and inasmuch as the medium cannot differ greatly in density, from the
centre to the circumference, the periodic times of the parts of the
vortex, must be directly as their distances from the axis, and
consequently the absolute velocities must be equal. If Mr. Redfield
resorts to a spirally inward current, it would be a centripetal instead
of a centrifugal current, and therefore could not cause the barometer to
fall, which was the best feature of the theory in its primitive form.
The absolute velocity of the wind is the important element which most
concerns us. In the case of a tornado of a few yards in diameter, there
is no doubt a circular motion, caused by the meeting of opposing
currents; but this may be considered a circle of a very small diameter.
The cause is due to a rapid escape of electric or ethereal matter, from
the crust of the earth, called forth by the progressing, disturbed space
above; this involves the air, and an ascending column in rotation begets
the rush on all sides to that column in straight lines: consequently,
the velocities will be inversely as the distances from the axis, and the
force of the current as the squares of the velocities. On the circular
theory, no increase of velocity would be conferred by the approach of
the centre, and consequently no increase of power.