The adjacent air, both on the north and south, being cooler, and, of course, heavier, would rush in to supply the place of the heated air.

This air coming from the regions beyond the tropics would, in its turn, be heated, and rise on reaching the warmer equatorial regions, giving place to a fresh supply, which, it is easy to see, must be furnished by the descent of that portion of air formerly heated at the equator, raised into the cold regions of the sky, and forced into a regular circuit by fresh elevations of heated air.

All these and many other interesting results are clearly developed in Daniell's Meteorological Essays, a book which every one at all interested in such inquiries will find it advantageous to study.

The first edition of this work was published in 1823, some years after these speculations had been forced upon my notice by a long course of service between the tropics.
It will be understood, that, as long as we imagine the globe at rest while this circulation is going on, the course of the lower air along the surface would be directly towards the equator, from due north in one hemisphere, and from due south in the other; while in the upper regions the currents would follow the opposite directions, and stream towards the poles.

But the instant we conceive the earth put into rotatory motion from west to east, a change would take place in the course of these aerial currents, both above and below.