across a tenth of the face presented to us—a distance, upon the scale of the gigantic image, so great that the motion required no painstaking observation, but forced itself upon the notice of the least attentive spectator. The belief of Martial astronomers is that Jupiter is not by any means so much less dense than the minor planets as his proportionately lesser weight would imply. They hold that his visible surface is that of an enormously deep atmosphere, within which lies, they suppose, a central ball, not merely hot but more than white hot, and probably, from its temperature, not yet possessing a solid crust. One writer argues that, since all worlds must by analogy be supposed to be inhabited, and since the satellites of Jupiter more resemble worlds than the planet itself, which may be regarded as a kind of secondary sun, it is not improbable that the former are the scenes of life as varied as that of Mars itself; and that infinite ages hence, when these have become too cold for habitation, their giant primary may have gone through those processes which, according to the received theory, have fitted the interior planets to be the home of plants, animals, and, in two cases at least, of human beings.
It was near midnight before the manifest fatigue of the ladies overcame my selfish desire to prolong as much as possible this most interesting visit. Meteorological science in Mars has been carried to high perfection; and the director warned me that but three or four equally favourable opportunities might offer in the course of the next half year.
