It is singular that, among all the orbs which circle around the sun, one only, and that almost the least of the primary planets, should exhibit clearly and unmistakably the signs which mark a planet as the abode of life. We have examined Mercury and Venus, the only other orbs which belong, like the earth and Mars, to the scheme of the minor planets, and we have found little to guide us to any certain conclusion respecting their physical habitudes. When we pass beyond the wide gap which separates the minor planets from the giant members of the solar family, we shall find much to attract our admiration, much to force upon us the belief that these orbs have been created to be the abodes of even nobler races than those which subsist upon our earth; but we shall find little to justify us in asserting that they resemble the earth in those habitudes which seem essential to the wants of terrestrial races. The planet Mars, on the other hand, exhibits in the clearest manner the traces of adaptation to the wants of living beings such as we are acquainted with. Processes are at work out yonder in space which appear utterly useless, a real waste of Nature's energies, unless, like their correlatives on earth, they subserve the wants of organised beings.