The axis of the planet Jupiter is always at right angles with a line drawn to the earth, consequently his poles are never presented to us; but his belts, which we can and do see, seem to speak loudly in favour of a plurality of spheres. The most common appearance of Jupiter is, that he is surrounded by four belts; two bright and two dark, alternate to each other. But they are variable, presenting different appearances; at some times seven or eight belts are discoverable, at other times they appear interrupted in their length, and to increase and diminish alternately, running into each other, and again to separate into a number of belts of a smaller size. If Jupiter be a solid globe, I would enquire, how is it possible to account for those various changes in his belts, or even for their existence at all? Astronomers, I understand, have heretofore considered the phenomena of Jupiter's belts as altogether unaccountable. If he be a simple plain globe, those belts could not exist; or if they did, they must forever remain uniform, and not change their size and shape, or relative positions in respect to each other; neither could the spots on one belt rotate faster than those on another. But if we adopt the doctrine of concentric spheres, and that this planet is composed of a number of them, we can account at once for all the various appearances in a rational manner. The belts would be produced by the shadow cast on the space between the polar opening of one sphere and the adjoining one; that is, a portion of the sunshine, would be reflected from the verges of the spheres on which it fell; and another portion would appear to be swallowed by the intervening space. And if refraction bends the rays of vision between and under his spheres, as it bends a portion of the rays of the sun, so as to produce the apparent belts of comparative shade, then a very complete solution of those appearances, heretofore considered wonderful, would be afforded. The variation which has been observed in their number, shape, and dimensions, can in no way be better accounted for, than by concluding the planet to be constituted of a number of concentric spheres, of different breadths, revolving on different axes, and with different velocities, so as sometimes to present to our view the verge of one sphere, and sometimes that of another: and the rays of the sun falling on the parts of the verges presented to us, would occasion the diversified appearances which we discover. If some sections of both crusts of the spheres be formed of water alone, and become occasionally transparent, it will afford an additional reason for the varying phenomena attendant on these appearances, which may also be increased by alternate regions of water, ice, dry land, and snow.