so insignificant, appeared to be moving in the opposite direction, so that it would ultimately be absorbed into the incandescent matter of the sun. Finally, it seemed that the moon would one day precipitate itself upon the earth. There was nothing doubtful or speculative in these sinister forebodings. The precise dates of the approaching catastrophes were alone uncertain. It was known, however, that they were very distant. Accordingly, neither the learned dissertations of men of science nor the animated descriptions of certain poets produced any impression upon the public mind. The members of our scientific societies, however, believed with regret the approaching destruction of the planetary system. The Academy of Sciences called the attention of geometers of all countries to these menacing perturbations. Euler and Lagrange descended into the arena. Never did their mathematical genius shine with a brighter lustre. Still the question remained undecided, when from two obscure corners of the theories of analysis, Laplace, the author of the 'Mécanique Céleste,' brought the laws of these great phenomena clearly to light. The variations in velocity of Jupiter, Saturn, and the moon, were proved to flow from evident physical causes, and to belong in the category of ordinary periodic perturbations depending solely on gravitation. These dreaded variations in orbital dimensions resolved themselves into simple oscillations included within narrow limits. In a word, by the powerful instrumentality of mathematical analysis, the physical universe was again established on a demonstrably firm foundation.