[2] Humboldt has already remarked (Cosmos, i. 95, and iii. 427), that the inner planets as far as Mars, and the outer ones beginning with Jupiter, form two groups having different properties. Also Encke. (See Humboldt's Note.)
[3] Printed Oct. 19, 1853.
[4] Herschel, 540.
[5] It is probable, from the small density of Jupiter's satellites, that they also consist in a great measure of water and vapor. Only one of them is denser than Jupiter himself.—Cosmos.
[6] It has, in our own day, even in the present year, been regarded as a great achievement of man to direct the fiery influences which he can command, so as to cast a colossal statue in a single piece, instead of casting it in several portions.
[7] Herschel, 900-905.
[8] Herschel, 901.
[9] Besides the curious relation of the times of rotation of the planets, just noticed, there is another curious relation, of their distance from the Sun, which any one, wishing to frame an hypothesis on the origin of our Solar System, ought by all means to try to account for.
The distances from the Sun, of the planets, Mercury, Venus, Earth, Mars, the Planetoids, Jupiter, Saturn, Uranus, are nearly as the numbers,
4, 7, 10, 16, 28, 52, 100, 196: