The progress of Astronomical discovery which has now been hastily traced, reminds us of the obligations we owe to those who have gone before us. While supplied with views respecting the constitution of the solar universe—the number, forms, magnitudes, distances, and movements of its members—upon the general accuracy of which the mind may repose with full satisfaction, the mode of its formation has been grappled with, and a theory presented, derived from the study of the sidereal heavens, which—though not demonstrable—is invested with a high degree of probability. The firmament exhibits dimly luminous appearances, like patches of white cloud, displaying various forms and peculiarities of structure, which are not resolvable into closely packed clusters of stars by any telescopic power, and whose phases are at variance with the idea that they are stellar groups, indistinct and blended from their remoteness. The nebulous substance, in one of its states, is evenly diffused, resembling a sheet of fog. Under another aspect, it is seen winding, and we detect a tendency toward structure, in the material congregating in different places, as if under the influence of a law of attraction. Definite structure appears in other cases, generally the spherical form, with great condensation at the centre, like regular stars in the midst of a thick haze. The question has hence naturally arisen, and it is one of profound interest—What do such appearances indicate? What do the differences in their character portend? Are they void and unmeaning substances in a universe of organization and order; or, are they advancing by a principle of progressive formation to share themselves in that order and organization? The idea has been started that, in these phenomena, we have an exhibition of the first state of the now organized bodies of our system, and of their progress to the ultimate conditions of their being, passing from one stage of construction to another, under control of the law of gravitation. This is substantially the nebular hypothesis of Laplace and Herschel: it supposes a diffused nebulosity, rotating with the solar nucleus, and extending beyond the bounds of the farthest planet, to have gradually condensed at the surface of the nucleus, accelerating thereby the solar rotation, and increasing the centrifugal force, by the action of which successive zones were detached, assuming spheroidal masses by the mutual attraction of their particles. This theory enlists a variety of evidence in its behalf. The fact of the projectile motions of all the planets and satellites taking place from west to east, in nearly the same plane—of their axical rotation likewise being all in the same direction, and corresponding with that of the solar body—is an instance of coincidence so extraordinary as strongly to support the theory of their common origin in obedience to a common law. It is no unimportant consideration