The appearance of Saturn, I conceive, establishes the fact, that the principle of concentric spheres, or hollow planets, does exist, at least in one instance, in the solar system. And if the fact be established that it exists in one case, is it not fair, nay, is it not almost a certain and necessary consequence, that the same laws of matter which formed one planet into concentric spheres, must form all the others on a plan more or less the same? If we draw any conclusion, or form any opinion at all, respecting the formation of the planets, whose inner parts we cannot see; or if we form any opinion in relation to our own planet in particular, whose poles have never been explored, would not reasoning from analogy bring us to the conclusion, that all bodies of matter are formed similar to that of Saturn, unless we have positive proof to the contrary? But it is not in Saturn alone that we find proof of the principles contended for by Captain Symmes. Most, if not all of the other planets, belonging to our system, whose relative situation afford us an opportunity of observation, appear to exhibit strong proofs that the same principles prevail throughout. The planet Mars, exhibits concentric circles round one or the other of his poles, according as either is more or less in opposition to us. These circles appear alternately light and dark, exactly as they should, supposing the planet to be constituted of concentric spheres, (such as Symmes believes of the earth) the light being reflected from their verges on which it falls; and in which case the vacant space between the spheres would necessarily appear dark. Sometimes he appears to us with a single ring at each pole. At such times his axis is at right angles, or nearly so, with a line drawn from the earth to his centre. This, I conceive, can be accounted for by the great refraction, occasioned by the increased density of his atmosphere around the poles, which appears to throw out the further sides of the verges so as to make them appear like rings, in the form they present themselves to our view. That such is the natural appearance may be evidenced by taking a small wooden sphere with open poles, and immerse it in a circular glass vessel filled with water; when viewed horizontally through the side of the glass, with the plane of the openings at a right angle with the visual ray, the refraction occasioned by the water, answering to the dense atmosphere of Mars, will apparently throw out the polar openings, and present you with a view, similar to the appearance of Mars, when his axis is at right angles to us.