PIERRE SIMON, MARQUIS DE, the greatest of recent physicists, was born March 23, 1749, at Beaumont, near Pont l'Evêque, in Lower Normandy. His father, a small farmer in the Vallée d'Auge, was too poor to send him to school, but some rich friends took an interest in the young scholar and sent him to the college of Caen, and afterwards to the military school of Beaumont. Though mathematics were at this time his favourite study, he seems to have paid a good deal of attention to theology. In his eighteenth year he went to Paris, furnished with introductions to D'Alembert and others. D'Alembert took no notice of his letter, till Laplace sent him an essay involving some of the higher principles of mathematics, when he invited him to his house, and shortly afterwards procured him a mathematical mastership in the military school of Paris. Laplace soon justified his choice by his papers read before the Academy of Sciences, of which, in 1773, he became an associate, and in 1785 a member. Before he was thirty years of age he had begun that career of discovery which only terminated with his life. It is not necessary here to recapitulate the details of his studies and their results, which are given in full in the Preliminary Dissertations of Sir John Leslie and Professor J.D. Forbes. When the Revolution broke out, Laplace became ambitious of political distinction. In 1796 he was one of the deputation which, in presence of the Council of Five Hundred, swore eternal hatred against royalty. A little later he dedicated to this same body his Exposition du Système du Monde. On the return of General Bonaparte from his campaigns in Italy, Laplace paid his court to him and secured his admission into the Institute. His good will was rewarded at a later period with the portfolio of the interior. But, as Napoleon afterwards said, "he carried into government the principles of the calculus," and managed matters so ill, that after six weeks of office it was found necessary to promote him to a sinecure in the senate. This occurred in 1799. Four years later he was made successively vice-president and chancellor of that body. Though he had sworn eternal hatred against kings and tyrants, he cheerfully took the oath of allegiance to Napoleon when he mounted the throne in 1804. His compliance was rewarded with numerous honours. He received the grand-cordon of the Legion of Honour in 1805, the title of count in 1806, the cross of grand-officer of the Legion of Honour in 1813, with many other distinctions. Yet when his benefactor's power began to wane, Laplace was among the first who voted for the overthrow of the imperial throne, and the restoration of the Bourbons. He even displayed a spirit of pusillanimous ingratitude to his fallen patron. He had dedicated to him, in very fulsome terms, his Théorie des Probabilités; in 1814, on the downfall of the empire, he suppressed this dedication. Shame or remorse for this time-serving may perhaps have prevented him from visiting the Tuileries during the Hundred Days. It is all the more creditable to him, however, that he did not go, as he had been assured of a kindly welcome. He carried a somewhat similar spirit into his writings, in which he withheld nearly all mention of any who had preceded him in his own branch of science, though liberal enough of praise to the great names in other departments of inquiry. On this point, however, it is unnecessary to dwell, as it has been already discussed in Professor Forbes' Dissertation. In 1816 Laplace was named by Louis XVIII. president of a commission for the reorganisation of the Polytechnic School, and in the following year became president of the Academy of Sciences. Before this date he had been elected a member of all the leading learned societies of Europe. At the time of his death, March 5, 1827, exactly a century after that of Newton, he had nearly completed his 75th year. The last words he was heard to utter were, "Ce que nous savons est peu de choses; ce que nous ignorons est immense."

The following list of Laplace's works is taken chiefly from La France Littéraire, by M. Quérard, and includes not only his separate publications, but also numerous memoirs, with which, during a period extending to rather more than half a century, he enriched the collections of the Academy and the Institute, and the Journal of the Polytechnic School:

1. Essai Philosophique sur les Probabilités, Paris, 1814, in 4to. Another edition of this work was published the same year in 8vo, and the work was reprinted in 1816, 1818, and 1825. The Essai Philosophique is merely an abstract of the large work on the same subject.

2. Exposition du Système du Monde, in five books, the fifth edition revised and augmented by the author, Paris, 1824, in 4to, and in two vols. 8vo. The first edition of this work appeared in 1796, in two vols. 8vo. In five books the author treats, 1st, of the apparent motions of the heavenly bodies; 2d, of the real motions of those bodies; 3d, of the laws of their motions; and, 4th, of the theory of universal gravitation. The fifth book contains an abridgment of the history of astronomy.

3. Précis de l'Histoire de l'Astronomie, Paris, 1821, in 8vo. This is merely the fifth book of the fifth edition of the Exposition du Système du Monde, published separately.

4. Théorie Analytique des Probabilités, third edition, revised and augmented by the author. The first edition of this work appeared in 1812, in 4to. From 1816 to 1825, M. de Laplace published four supplements, which the publisher, after having sold them for some years separately, added to the volume to which they now serve as a complement. These supplements treat, 1st, of the application of the calculus of probabilities to natural philosophy; 2d, of the application of the calculus of probabilities to geodetical operations; and, 3d, of the application of geodesical formulae of probability to the meridian of France. The fourth contains an abridgment of the theory of probabilities.

5. Théorie des Attractions Sphériques, et de la Figure des Planètes, Paris, 1785, in 4to. This is a memoir extracted from the collection of the Academy of Sciences.

6. Théorie du Mouvement et de la Figure elliptique des Planètes, Paris, 1784, in 4to. This work was printed at the expense of Pre-