The theory assumes that both the land and water, under this central belt, where the air is supposed to be rising are _materially hotter_ than the land and ocean are on _either side of it_. Now, how much hotter are the air and the land under the belt of rains and calms, upon Hindoostan, or Africa, or South America, where the former is supposed to be acquiring heat and expansion so rapidly, and to be ascending, than under, and in the dry belts on either side? None; it is cooler by the thermometer--_much cooler_. The central belt of rains in midsummer over Africa, extends up as far as 17 deg. north latitude, and perhaps further. North of this line over the whole surface of the desert, the Barbary States, a part of the Mediterranean, and some portion of Italy, the dry season extends, and from the entire surface the N. E. trade blow into the central belt.[1] Over the desert they all pass. Now this desert is a sea of sand, under a vertical sun, intensely heated, blistering the skin with which it comes in contact, and often acquiring a temperature of 150 deg. to 160 deg. of Fahrenheit. Under the central belt of rains neither 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._