"A Napoleon-le-Grand.-Sire, La bienveillance avec laquelle V.M. a daigne accueillir l'hommage de mon traits de Mecanique Celeste, m'a inspire le deair de lui dedier cet ouvrage our le calcul dee Probe bilites. Ce calcul delicat s'etend aux questions lee plus importantes de la vie, qui ne sent en effet pour la plupart que des problbmes de probabilite. B doit sur ce rapport interesser V.M., dont le genie sait ei bien apprecier et si dignement encourager tout ce qui peut con tribuer au progres dee lumieres et de la prosperite publique. Jose la supplier d'agreer ce nonvel hommage diets par la plus wive recon naissance, et par les sentimene profonde de radmiration et de respect avec lesquele ye Sire, de V. M. le tres humble et tree obeissant serviteur et &del° sujct, Laplace." As if to make such a suppression as striking as possible, Laplace had said, ten years before, in the dedication of the third volume of the '316canique Celeste,' to the First Consul, "Puisse cct ouvrage, consacre h la plus euhlime des sciences naturelles, etre un monument durable de la reconnaissance quo votre accueil et lee bienfaits du gouvernement inspirent hoeux qui les cultivent. Do tonic., lee verites qu'il renferme, l'expreesion de ce sentiment sera toujoure poor moi Is plus precieuse." Laplace did not live to publish the second edition of the • 316canique Celeste.' After the final Restoration Laplace's only public employments were of a scientific character, and he died on the 5th of May 1827. His last words were, "Ce que nous connaissons cat pen de chose; ce que g nous inorons eat immense." "The Anther of the Mecanique Celeste," to use a common synonyme for Laplace, must be an object of the admiration of posterity as long as any record of the 18th century exists. With the exception of some experiments made in conjunction with Lavoieier, to determine the quantity of heat in different bodies, we do not find that Laplace was employed in sane' experiment. But for many years he was the head, though not the hand of European astronomy ; and most of the labours of observation were made in directions pointed out by him, or for the furtherance of his discoveries iu the consequences of the law of gravitation. Before however we begin to speak of them, there is an important caution, for the want of which a reader of the ‘Mecanique Celeste' might even overrate Laplace, great as he is.
The French school of writers on mathematical subjects has for a long time been wedded to the reprehensible habit of omitting all notice of their predecessors, and Laplace ie the most striking instance of this practice, which be carried to the utmost extent. In that part of the ' Mecanique Celeste' in which ho revels in the results of Lagrange, there ie no mention of the name of the latter. The reader who has studied the works of preceding writers will find him, in the Theorie des Probabilitds,' anticipated by De Moivre, James Bernoulli, etc., on certain points. But there is not a hint that any one had previously given thoao results from which perhaps his sagacity led him to his own more general method. The reader of the 'MCcanique Celeste • will find that, for anything he can see to the contrary, Euler, Clairaut, D'Alembert, and abovo all Lagrange, need never hove existed. The reader of the Systeme du Monde' finds Laplace referring to himself in almost every page, while now and then, perhaps not twenty times in all, his predecessors iu theory are mentioned with a scanty reference to what they have done; while the names of observers, between whom and himself there could be no rivalry, occur in many places. To such an absurd pitch is this sup
pression carried, that even Taylor's name is not mentioned in con nection with his celebrated theorem; but Laplace gravely informs his readers, " Nous donnerons quelques theoremes gCneraux qui nous eeront utiles dons la suite," those general theorems being known all over Europe by the names of Maclaurin, Taylor, and Lagrange. And even in his Theory of Probabilities,' Lagrange's theorem is only "la formula (p) du rumen) 21 du second livre " de la Mecanique Celeste. It is true that at tho end of the Mecanique Celeste' he gives historical accounts, in a condensed form, of the discoveries of others ; but these accounts never in any one instance answer the question Which pages of the preceding part of the work contain the original matter of Laplace, and in which is he only following the track of his predecessor 3 The consequence is, that a student who has followed the writings of Laplace with that admiration which they must command, is staggered when he comes afterwards to find that in almost every part of the work there are important steps which do not belong to Laplace at all. He is then apt to imagine that when be reads more extensively he shall find himself obliged to restore more and more to the right owner, until nothing is left which can make a reputation such as is that Laplace with the world at large. Such an impression would be wholly incorrect; but it would be no more than the just reward of the practice of suppression. Nevertheless the researches on the figure of the planets in the Mecanique Celeste,' and the general method of the Theorie des Probabilites ' for the approxima tion to the values of definite integrals, are alone sufficient, when all needful restoration has been made, to enable us to say, that Laplace was one of the greatest of mathematicians.
The first two volumes of the Mecanique Celeste' appeared in the year VII. of the Republic (which lasted from the 22nd of September 1798, to the 21st of September 1799), and may have been the induce ment of the First Consul to make Laplace a member of the govern ment. The third volume appeared in 1802, the fourth in 1805, and the fifth in 1825. A posthumous Supplement has appeared. The headings of the chapters throughout will be a more useful appendage to an article in a work of reference than any account which we could find room for, especially with regard to a philosopher whose dis coveries are, like those of Newton, dwelt on in every popular work.
In vol. 1. are found Boole I. On the General Laws of Equilibrium and Motion.-Chap. 1, On the Equilibrium and Composition of Forces which act on a Mate rial Point; chap. 2, On the Motiou of a Material Point ; chap. 3, On the Equilibrium of a System of Bodies ; chap. 4, On the Equilibrium of Fluids; chap. 5, General Principles of the Motion of a System of Bodies; chap. 6, On the Laws of Motion of a System of Bodies, for all Relations between the Force and Velocity which are mathematically possible ; chap. 7, On the Motion of a Solid Body of any Figuro; chap. S. On the Motion of Fluids.