llustration we have used.

The vortex passing off from O, (Fig. 20,) although it does not actually
reach the surface of the atmosphere, affects the equilibrium of the
ether, and, for a short distance from the parent vortex, may cause an
ascensional movement of the air. If to this is conjoined a northerly
wind from the vortex, a band of clouds will be produced, and perhaps
rain; but violent storms never occur in the intervals, except as a
steady gale, caused by the violence of a distant storm. Thus, it will
frequently be noticed that these vortices are flanked by bands of
clouds, which pass southward, although the individual clouds may be
moving eastward. Hence, instead of disproving the theory, they offer
strong evidence of its truth; and could we view the earth from the moon
with a telescope, we should no doubt see her beautifully belted.

[Illustration: Fig. 20]

But it may be again asked, why should not the weather be the same
generally, in the same latitude, if this theory be true? If the earth
were a globe of level land, or altogether of water, no doubt it would be
similar; but it must be remembered, that both land and water are very
unequally distributed: that the land is of varying extent and
elevation--here a vast plain, far removed from the ocean, and there a
mountain chain, interposing a barrier to the free course of the
atmospheric currents; sometimes penetrating in full width into the
frigid zone, and again dwindling to a few miles under the equator. One
very important distinction is also to be remarked, in the superficial
area of the different zones, reckoning from the equator, and taking the
hemisphere as 100 parts:

Frigid zone 8 parts.
Temperate " 52 "
Torrid " 40 "

For as the time of rotation in every latitude is the same, the area to
be disturbed in the same time, is less in high latitudes, and there a
greater similarity will obtain, _ceteris paribus_. In lower latitudes,
where both land and water stretch away for thousands of miles, it is not
wonderful that great differences should exist in the electrical and
hygrometric state of the air.

The summer of many countries is always dry--California for instance. In
winter, in the same country, the rains are apparently incessant. This of
course depends on the power of the sun, in diverting the great annual
currents of the atmosphere. As long as the dry north-west trade sets
down the coast of California, the circumstances a