they are the more transparent parts of Jupiter's atmosphere, while the brighter parts are the region of clouds which reflect the light more abundantly. In this hypothesis, we see the body of the planet down through the transparent region of dark belts; but it is more probable that, in the dark belts, we see only a part of an interior shell, and that the real body may He far beneath. The dark belts would, in this way, correspond to the penumbra of the spots in the sun, which is only an micovered part of the stratum immediately under the luminous envelope. Jupiter is by far the largest of the planets, and yet it may have only a small solid nucleus. Though, taken as a whole, Jupiter is not heavier than a sphere of water of the same size, we can readily suppose the real body of the planet to be of much heavier matter. It may be compared to a bullet of lead forming the core of a sphere of cork. Dr Whewell's argument then is of no force, when he holds that Jupiter can only be the abode of molluscs, and other lower forms of life suited to a watery abode. Even though the body of Jupiter had only the density of water, it would not at all be necessary to assume that it must necessarily be fluid, for we know of many solid substances as light as water. But there is no necessity for holding that its density is only that of water. The Jovial ball may be as dense as that of the earth, and may afford to the teeming inhabitants as sure a footing as our roads and streets.
