ot ordinarily over one or two hundred miles in
diameter, and often less. There are trades all the way over from Africa,
and S. W. winds also, if they exist, as he supposes, in the West Indies.
How can it happen that this lateral overflow should pass _without effect_,
over 2,500 miles of S. W. wind and trade, and concentrating the overflow
of a continent over one small and chosen spot of the West Indies, _pitch
down_ there, and there only, and crowd the S. W. wind into the trade
below? This is too much for sensible men to believe.

What does Professor Dove mean by the term _impulsion_, as applied to the
winds? How are they _impelled_? It is the fundamental idea of his
calorific theory, that they are _drawn_ by the _suction_ caused by a
_vacuum_, and the vacuum created by expansion and overflow above, in
obedience to the law of gravity; that the S. E. trade is drawn to the
great region of expansion, and the S. W. runs from it as an overflow. But
if the S. W. is driven down into the plane and place of the
surface-trades, how does it continue to be impelled, and why is it not
then subject to the suction of the vacuum which draws the trade? Does that
vacuum _select its air_, and so attract the trade, in preference to the
depressed portion of the S. W. current, that the former runs around the
latter to get to the vacuum, and the latter around the former to get away
from it? And does the trade, when it has got around the S. W. current,
instead of going to the vacuum, continue to gyrate, and the S. W. current,
instead of pursuing its regular course, gyrate also about the trade, and
both move off together, regardless of the vacuum of the great region of
expansion, in a new direction to the N. W., in an independent,
self-sustaining, cyclonic movement, increasing in power and extent,
involving extended and increasing condensation, producing the most violent
electrical phenomena, and thus continuing up, even to the Arctic circle?
Yes, says Professor Dove. No, say all fact, all analogy, and his own
principles.

7. His theory relative to the typhoons is unintelligible. If they
originate near the lateral confines of the great region of atmospheric
expansion, they originate in the region of the trade-winds, for the two
are identical. How the direct pressure of the air from the trade-wind over
the Pacific, in the more expanded air of the monsoon region, can occasion
a typhoon upon any principles, passes my comprehension. If, as Lieutena