CHAPTER IV.
Arguments in support of Symmes's Theory, drawn from celestial appearances.
That a disposition to hollow cylinders does exist in nature, I think, must be admitted; and that a similar principle exists in the planetary system, at least in some degree, appears to me as certain. Every person has seen or heard of Saturn and his rings. At certain periods of time the appearance of this planet, viewed through a good telescope, represents him to be surrounded with two luminous rings or bodies of matter, concentric with each other, and with the body of the planet. These rings no where adhere to the body of the planet, but are distinct and separate, some considerable distance from him, and from each other, leaving a portion of vacant space between the planet and the rings, through which we see the fixed stars beyond.[4] It is a fact, I believe, admitted by all, and of which we have positive ocular demonstration, that these rings are constituted of some kind of matter, if not solid, at least to all appearance as much so as the body of the planet. Their thickness must be very inconsiderable, for when the edge is turned to the eye it is no longer visible, except to the powerful reflecting telescope of Dr. Herschel.—Thus the rings undergo phases according to the position of the planet in his orbit, which prove them to be opaque, like other bodies in the planetary system, and like them shining by reflection. I am not informed what is the precise velocity of the rotary motion of the rings; probably their varying aspect, or some other cause has prevented a correct observation from being made. However, the planet itself revolves on its axis, with an astonishing velocity; and no doubt the rings also, though perhaps with different degrees of velocity.
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.
Our next neighbour, Venus, between us and the sun, (though her being between us and the sun prevents us from having so favourable an opportunity of examining her poles, as those of Mars, who is our next neighbour on the side opposite the sun) presents appearances at certain times, which seem to lead to the conclusion, that she also is constituted of concentric spheres. At times, when this planet is nearly a crescent, we are able to discover a deficient space near the tip of one of her horns. Admitting Venus to be constituted of concentric spheres with open poles; and supposing one of the vacant spaces, between two of her spheres about the polar openings, to traverse her horn or cusp, at the place where the dark space occurs,—it would present to us exactly such an appearance as does actually occur.
At other times, one of the horns or cusps of Venus is seen to wind inward as it were into the body of the planets, extending about fifteen degrees further than the other horn. This is an appearance which would also be presented, if Venus is formed according to Symmes's theory. And again, supposing one of her horns to terminate around the verge of a polar opening, in such way as to follow the curve of the verge for some distance, (which is of course more curved than the periphery of the planet) and the same appearances, I think, would occur. The axis of the planet not being at right angles with the polar openings, in its revolutions one side of the verge would be thrown much nearer to us than the other; and the different spheres revolving on their axes with different velocities would at different times exhibit to our view the verge of a different sphere.[5]