24. Before the planetary bodies have attained a degree of coolness sufficient for solidification, smaller bodies, veritable liquid globules, are detached from some in the equatorial plane, — a plane in which the centrifugal force is the greatest, — and which by virtue of the same laws have acquired a movement of translation around their planetary generatrix, like theirs around their central astral generator.
Thus the Earth has given birth to the moon, the body of which, being smaller, has cooled in a shorter time. Now the laws and forces which presided at its detachment from the terrestrial equator and its movement of translation in this same plane, act in such a way, that this world, in place of being invested with the spheroid form, takes that of an ovoid globe; that is to say, having the elongated form of an egg, the center of gravity in the inferior part.
25. The conditions by which the distinctive form of the moon was effected would permit it scarcely to quit the Earth, and constrain it to remain perpetually suspended in its sky like an ovoid figure, of which the heaviest parts form the lower face turned toward the Earth, and of which the least dense parts occupy the summit, which is the side opposed to the Earth, elevating itself towards the heavens. This is the reason that this body presents continually the same face to us. It can be likened, in order to better comprehend its geological state, to a globe composed of cork, of which the base, turned towards the Earth, is formed of lead.
Hence two essentially distinct natures are found upon the surface of the lunar world, — one without any possible analogy with ours, for fluid and ethereal bodies are unknown to it; the other, relatively analogous to the Earth, since all the least dense substances are found upon this hemisphere. The first, perpetually turned towards the Earth, is without atmosphere or water, except maybe at the boundaries of this sub-terrestrial hemisphere; the other, rich in fluids, is perpetually opposed to our world. *
* This entirely new theory of the moon explains, by the law of gravitation, the reason why this body always turns the same face toward the earth. Its center of gravity, instead of being in the center of the sphere, is to be found upon one of the points of its surface, and, consequently, attracted to the earth by a greater force than are the lighter parts. The moon produces the effect of figures called Poussahs, which constantly stand upright upon their base, while the planets, whose centers of gravity are at equal distances from the surface, turn regularly upon their axes. The vivifying fluids, gaseous or liquid, on account of their specific lightness, would be found accumulated in the superior hemisphere constantly opposed to the earth. The inferior hemisphere, the only one we see, must be destitute of them, and consequently incapable of sustaining life, whilst life would reign on the other. If, then, the upper hemisphere be inhabited, its inhabitants have never seen the earth, unless by excursions into the other hemisphere, which would be impossible for them, since it lacks the necessary conditions of vitality. However rational and scientific this opinion may be, as it has not yet been confirmed by any one direct observation, it can be accepted only as an hypothesis; and as such it serves as a beacon-star to science. But one has to agree that up to the present, it is the sole satisfactory explanation of the particularities presented by this satellite.
26. The number and condition of the satellites of every planet have been carried according to the special conditions of their formation. Some have given birth to no secondary body, — Mercury, Venus, and Mars25, for instance; whilst others have formed one or many, like the Earth, Jupiter, Saturn, and others.
27. In addition to its satellites, or moons, the planet Saturn presents a special phenomenon of the ring, which seems from afar, to surround it like a white aureole. This formation is to us a new proof of the universality of the laws of nature. This ring is surely the result of a separation which took place in primitive times in the equator of Saturn, just as an equatorial zone has been thrown off from the Earth, and formed its satellite. The difference consists in this that the ring of Saturn was found formed in all its parts of homogeneous molecules, probably already in a certain state of condensation, and enabled in this manner to continue its rotary movement in the same way, and in a time nearly equal, to that which revolves the planet. If one of the points of this ring had been denser than another, one or many agglomerations of substance would have been suddenly expelled, and Saturn would have counted many satellites more. Since the time of its formation, this ring has been solidified, as well as the other planetary bodies.