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176 quite applicable to them, as they unquestionably have measurable motions of their own. Those belonging to the latter are called erratic or wandering stars, popularly planets, from a Greek word signifying a wanderer; these include the sun, moon, our own earth, and the other planetary bodies, as well as the comets. The erratic stars constitute, with the sun—about which they move as their common centre or focus, in obedience to the great universal law of gravitation revealed to us by the genius of Newton and his sublime predecessor the illustrious Kepler—the solar system, which, however so infinitesimally small in comparison to the infinite magnitude and extent of the sidereal world, men must naturally regard with greater and more vivid—nay, if the expression may be permitted us, with more affectionate—interest than the universe beyond. Moreover, the bodies composing this system are comparatively near to us, and more within the reach of our observation, than the fixed stars, which are placed at immeasurable distances from us. Let us, therefore, first take, as we are being wafted on with our planet through space, a rapid survey of them, before proceeding to the contemplation of the “world of worlds” beyond.

By a long series of patient observations of a most delicate kind, aided by the telescope and other marvellous instruments devised by human ingenuity, and by refined combinations of theoretical reasoning and logical induction, man has succeeded in