HISTORY OF PHYSICAL ASTRONOMY.

place conventionalities of ordinary minds; and, guided by the eagle eyeof genius, explored the secret springs which animate a whole system ofworlds. We cannot convey to the general reader a more adequate idea ofthe merits of the incomparable work just mentioned, than byciting the judgment pronounced upon it by the most illustrious ofNewton ’s followers. Laplace, after enumerating the various astronomicaldiscoveries first announced in the Principia, concludes in the followingterms:—“ The imperfection of the Infinitesimal Calculus, when first dis-covered, did not allow Newton to resolve completely the difficult problemswhich the system of the world offers, and he was often compelled to givemere hints, which are always uncertain until they are confirmed by arigorous analysis. Notwithstanding these unavoidable defects, the numberand generality of his discoveries relative to this system, and many of themost interesting points of the Physico-mathematical sciences, the multi-tude of original and profound views, which have been the germ of themost brilliant theories of the geometers of the last century, all of whichwere presented with much elegance, will assure to the Principia a pre-eminence above all the other productions of the human intellect.” *

CHAPTER II.

Newton ’s Intellectual Cliaracter considered in connexion with his Scientific Researches.—His Inductive Ascent to the Principle of Gravitation.—Motion of a Body in anOrbit of Variable Curvature.—Attraction of a Spherical Mass of Particles.—Develope-

ment of the Theory of Gravitation.—General Effects of Perturbation_Inequalities of

the Moon computed_Aid afforded by the Infinitesimal Calculus.—Figure of the

Earth_Attraction of Spheroids_Precession of the Equinoxes —General accuracy of

Newton ’s Results.—Anecdotes illustrative of his Natural Disposition.'—His Death andInterment.

Newton was singularly endowed with all those qualities which enable themind to unfold the laws of the material world. He could detect with aglance the distinctive features of natural phenomena, and with mar-vellous sagacity divine the principles on which they depended. Withthese valuable qualities he combined a proneness to generalization, whichconstantly led him to connect together the facts he was contemplating,and advance from them to more comprehensive views of the operations ofnature. He possessed also powers of mathematical invention adequate onall occasions to surmount the difficulties he might encounter, either inascending by induction to general laws, or in subsequently redescendingfrom them to the explanation of their various consequences. When weconsider, moreover, that he was imbued with an extreme love of truth,which induced him to reject all speculations, however ingenious andbeautiful, that were not reconcileable with facts—that his whole soul waswrapped up in the study of nature and her works, and that he possessedin an extraordinary degree the power of concentrating the whole energiesof his intellect upon the object of his researches, we may form someconception of the advantages under which he approached the examinationof physical questions. It is, in fact, in consequence of his possession of

* Exposition du Systeme du Monde, liv. v. chap. v.

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