The most extraordinary feature of these bodies is the proximity of the inner satellite to the planet, and the consequent rapidity of its motion. The distance of the inner satellite from the centre of Mars is about 6,000 miles, and from surface to surface it is less than 4,000 miles, or a little more than the distance from New York to San Francisco. The shortest period of revolution of any satellite previously known, is that of the inner satellite of Saturn, which is a little more than 22½ hours; but the inner satellite of Mars accomplishes its revolution in 7h. 38m., or in 17 hours less than the period of rotation of the planet upon its axis. The period of revolution of the outer satellite is greater, of course, and equals 30h. 7m. From this rapidity of motion of the inner satellite of Mars, a very curious result follows, which at first sight may appear in contradiction with the fact that this body has a direct motion, like that of all the planets of the solar system, and moves around Mars from west to east. While the outer satellite of this planet, in company with all the stars and planets, rises in the east and sets in the west, the inner satellite, on the contrary, rises in the west and sets in the east. Since the period of rotation of Mars is greater than is the period of revolution of this satellite, it necessarily follows that this last body must constantly be gaining on the rotation, and, consequently, that the satellite sets in the east and rises in the west, compassing the whole heavens around Mars three times a day, passing through all its phases in 11 hours, each quarter of this singular Moon lasting less than 3 hours. It has been shown above that Mars has many points of resemblance to the Earth. It has an atmosphere constituted very nearly like ours; it has fogs, clouds, rains, snows, and winds. It has water, or at least some liquids resembling it; it has rivers, lakes, seas and oceans. It has also islands, peninsulas, continents, mountains and valleys. It has two Moons, which must create great and rapid tides in the waters of its seas and oceans. It has its days and nights, its warm and cold seasons, and very likely its vegetation, its prairies and forests, like the Earth. On the other hand, its year and seasons are double those of the Earth, and its distance from the Sun is greater. Is this planet, which is certainly constituted very nearly like our globe, and seems so nearly fitted for the wants of the human race, inhabited by animals and intelligent beings?