Now we notice at once how importantly these researches into the sun’s structure bear upon the subject of this treatise. It would be indeed interesting to consider the actual condition of the central orb of the planetary scheme, to picture in imagination the metallic oceans which exist upon his surface, the continual evaporation from those oceans, the formation of metallic clouds, and the downpour of metallic showers upon the surface of the sun. But apart from such considerations, and viewing Kirchhoff’s discoveries simply in their relation to the subject of other worlds, we have enough to occupy our attention. If it could have been shown that, in all probability, the substance of the sun consists of materials wholly different from those which exist in this earth, the conclusion obviously to be drawn from such a discovery would be that the other planets also are differently constituted. We could not find any just reason for believing that in Jupiter or Mars there exist the elements with which we are acquainted, when we found that even the central orb of the planetary system exhibits no such feature of resemblance to the earth. But now that we know, quite certainly, that the familiar elements, iron, sodium, and calcium, exist in the sun’s substance, while we are led to believe, with almost perfect assurance, that all the elements we are acquainted with also exist there, we see at once that, in all probability, the other planets are constituted in the same way. There may of course be special differences: in one planet the proportionate distribution of the elements may differ, and even differ very markedly, from that which prevails in some other planet. But the general conclusion remains, that the planets are formed of the elements which have so long been known as terrestrial; for we can not recognize any reason for believing that our earth alone, of all the orbs which circle around the sun, resembles that great central orb in general constitution.