s so. The south pole may be situated nearer the geographical
pole than the north one--but this is not believed to be so, nor could it
make the difference. The greatest southern depression of the magnetic
equator is found where the lines of greatest intensity, and of no
variation, are found; and at the more intense of these lines exists the
greatest depression. From this, I think, it may be inferred that the
needle is affected by the greater magnetic intensity of the northern
hemisphere, to which it may yet appear the obliquity of the earth's axis
is owing. However this may be, or whatever the cause, no marked effect is
produced upon the trades. The S. E. trades, by reason of the greater
extent of ocean-surface on which they originate, are every where the most
extensive, regular, and forcible. The south polar waters, from which they
rise, are every where trenching upon, and overriding, the north polar
ones; and thus, by a most beneficent provision, the greater portion of the
habitable surface is placed in the northern hemisphere, and the principal
portion of the southern is left open to an extensive, active evaporative
action, which supplies the northern habitable surface with a large excess
of the needed moisture.

The condensation, and consequent precipitation, which takes place at the
passing of the trades, as we have already said, over the ocean and
lowlands, takes place mainly in the day-time. Upon the table-lands and
mountain-ranges, it often continues during the evening and night. The
morning, and early part of the day, however, in tropical countries, are
generally fair at all elevations.

Storms also originate in the equatorial belt, and issuing forth in great
volume and with great intensity of action, find their way up even within
the Arctic circle. Those which pass over this continent, or the northern
Atlantic, generally originate in the West Indies, some of them over the
Caribbean Sea, some over the islands, and some over the open ocean to the
east of them; and, nearly all the most violent, during the months of
August, September, and October. It would seem most probable that the
primary action in such cases was in the trades themselves, but it is by no
means certain that such is the case. This is the class of storms of which
Mr. Redfield has industriously investigated some twenty or more; Mr. Espy
some, and Lieutenant Porter two. Their course, when very violent, is often
more directly north than that of storms