The equatorial zone of Jupiter is occupied most of the time by a broad, prominent belt 20° or 30° wide, limited on each side by a very dark narrow streak. Between these two dark borders, but seldom occupying the whole space between them, appears an irregular white belt, apparently composed of dense masses of clouds strongly reflecting the Sun's light, some of these cloudy masses being very brilliant. The spaces left between the cloudy belt and the dark borders, usually exhibit a delicate pink or rosy color, which produces a very harmonious effect with the varying grayish and bluish shades of some of the belts and streaks seen on the disk. Quite often the cloudy belt is broken up, and consists of independent cloudy masses, separated by larger or smaller intervals, these intervals disclosing the rosy background of this zone. On each side of the equatorial belt there is usually a broad whitish belt, succeeded by a narrow gray band; the space left on each hemisphere between these last bands and the limb being usually occupied by two or three alternate white and gray bands. A uniform gray segment usually forms a sort of polar cap to Jupiter. When observed under very favorable conditions, all the lighter belts appear as if composed of masses of small cloudlets, resembling the white opaque clouds seen in our atmosphere. This, as already stated, is particularly noticeable on the equatorial belt. It is not unusual, when Jupiter is in quadrature, to see some of the most conspicuous white spots casting a shadow opposite to the Sun; a fact which sufficiently indicates that these spots are at different levels. They probably form the summits of vast banks of clouds floating high up in the atmosphere of Jupiter. What we see of Jupiter is chiefly a vaporous, cloudy envelope. If our sight penetrates anywhere deeper into the interior, it can only be through the narrow fissures of this envelope, which appear as gray or dark streaks or spots. That most of the visible surface of Jupiter is simply a cloudy covering, is abundantly proved by the proper motion of its spots, which sometimes becomes very great.