the earth nor air exceed the temperature of
84 deg.. And yet the hot air of the desert does not ascend, but blows into
this cooler central belt; and when it is felt as it blows off the western
coast by the mariner, or even in Guinea, when the belt of rains has gone
south in winter, as it often is as the _harmattan_, it is suffocating and
intolerable. There, then, not only is it untrue, that the land and the air
over it under the rainy belt are hotter, but it is true that intensely
heated air blows horizontally from the Desert of Sahara. Nay, as it will
appear in the sequel, this hottest of all surfaces not only can not have a
vortex, but it can not induce a monsoon, and scarcely a sea breeze. The
same is true in a great degree of the surface, and the air over it, on
either side of the supposed vortex of the rainy belt upon South America.
See the description of Humboldt, already given, where the thermometer
stood as high as 115 deg. of Fahrenheit in the shade, while the N. E. winds,
the regular trades, were blowing over the land. And it is equally true of
Arabia, and indeed of every portion of the earth. There is not a spot upon
the globe where the land and the air are cooler _by the side_ of the
central belt of rains, than _under it_. _And the opposite is true every
where upon the land._

How much hotter is the ocean and air under this supposed vortex? But
little hotter than they are on the side where the sun is not vertical,
_and none on the other_. Let us be a little more particular. The
temperature of the Atlantic under the belt of rains in our winter, and on
the south of the belt at the latitude of 3 deg. south, and down to 9 deg. or more
south, is 82 deg.. The air may range a degree, or possibly two, higher than
the water at either point. On the north this difference is from nothing at
the meeting of the trades and belt of rains, to about 4 deg. at their northern
limit. This is too _trifling_ to be worth one moment's consideration. It
is less, far less than the difference between the water and air of the
Gulf Stream which runs along our coast, and the adjoining waters and air
over them. While on the south side of the belt of rains the _difference is
actually against the theory_--and the same state of things is reversed in
summer, when the sun is vertical at the north.

From the log of an intelligent shipmaster, found in the wind and current
charts of Lieutenant Maury, I abridge the following, which will illustrate