We can here do no more than mention the analysis of the phenomena of the tides, one of the most important and most brilliant of Laplace’s performances. Indeed there is no branch of Physical Astronomy, we might almost say of physics in general, which is not materially indebted to him. Superior to Euler in the power of conquering analytical difficulties, he is almost his equal in the universality of his labours. The great work of Laplace is the ‘Mécanique Céleste,’ a collection of all that had been done by himself or others, concerning the theory of the universe. It is far above the reach even of the mathematical reader, unless he has given a degree of attention to the subject, which few, at least in our day, will exert. But Laplace was an elegant and clear-headed writer, as well as a profound analyst. He has left, we will not say for the common reader, but for those who possess the first elements of geometry, a compendium of the Mécanique Céleste, in the ‘Système du Monde.’ This work is free from mathematical details, and, were it his only production, would rank him high among French writers. We recommend it as the best exposition of the present state of our knowledge of the solar system. But if it be said that Laplace was much indebted to the labours of Lagrange and others, for the methods which form the basis of the Mécanique Céleste, which is undoubtedly true, we have a splendid instance of what might have been expected from him under any circumstances, in the ‘Théorie des Probabilités.’ The field was here open, for though the leading principles of the science had been laid down, and many difficult problems solved, yet some method was still wanting by which sufficient approximation might be made to problems involving high numbers. In the theory of chances the great complexity of the operations required, soon renders the application of the clearest principles practically impossible; or, we should rather say, would have done so had it not been for the researches of Laplace. His work on this subject is, in our opinion, even superior to the Mécanique Céleste, as a proof of the genius of the author. The difficulties above described disappear under an analysis more refined and artificial than any other which has ever been used. The mathematician may or may not read the Mécanique Céleste, according to whether he would wish or not to turn his attention to physical astronomy; but the analyst must study the Théorie des Probabilités, before he can be said to know of what his art is capable. The philosophical part of his work, with its principal results, was collected by the author in the ‘Essai Philosophique sur les Probabilités,’ in the same manner as those of the Mécanique Céleste were exhibited in the Système du Monde.