the lower regions of the air loaded with moisture and clouds; and were he to see down through the crust of the earth, he would in all probability discover a concentric arrangement of the interior.
In the case of Jupiter and Saturn, it is obvious that we see only the outer shell, within which the bodies of the planets are concealed. The disc of Jupiter presents very singular phenomena. There are indications of constant commotion, and the markings of the belts often present very perplexing forms, of which no account can be given. We only know that the visible disc is not a fixed and solid crust. It is like the visible envelope of the sun, which conceals the solid nucleus in its interior. The shadows of the satellites are seen as dark spots when they cross the disc of the planet, and the satellites themselves can also at the same time be detected by powerful telescopes. Besides these, there are other spots of which no account can be given. They sometimes appear in clusters, as shewn in our figure of the planet. They have a proper motion like the spots on the sun, and, probably, are due to the same general cause—the rotation of the body combined with the higher temperature of the equatorial regions. They will, therefore, correspond with the circular storms or cyclones in the atmosphere of our globe. There is no evidence that we have ever as yet seen the kernel within the outer shell of Jupiter. The usual explanation of the dark belts of Jupiter is, that
