LA.PLACE, PIERRE SIMoN, Marquis de (ante). Laplace's great field was mathemat ical astronomy, and he stands second to 11011C, except Newton, in this highest of all scientific branches. To him we owe the demonstration of the invariability of the major axis of the planetary orbits, as well as the inequality of the motions of Jupiter and Saturn. He also solved the problem of the mean motion of the imm, and those con nected with the moons of Jupiter. It was his knowledge of physical principles to which he owed his wonderful scientific sagacity, which was also shown in ninny depart ments of physics, as in the construction of calorimeters. In his investigation of the discrepancies between theorrical and observed velocity of sound, his calculations for barometrical measurement and for atmospheric refraction, as well as tidal phenomena, he exhibited distinguished pre-eminence. In his numerous works, however, Laplace failed to refer to the labors of his predecessors and contemporaries, which makes it dif ficult for the student to distinguish between his own work and that of others, and on this account some have looked upon him as a compiler quite as much as a discoverer. In one important particular he fails to give credit to his great contemporary Lagrange, and refers to one of his most splendid mathematical solutions as being• a formula (No. 21 of the second book) of the .illecanique Celeste; and the works of other mathemati
cians are overlooked, while references to his own are extremely numerous; but for as this it is remarked by mathematicians that any one of his original researches would place the stamp of mathematical genius upon any man. There is a translation of the Mecanique Celeste, by Nathaniel Eowditch (2 vols., Boston, 18291. See BOWDITCH; and Mrs. Somerville's Mechanism of the heavens is a synopsis of a portion of that work.' Laplace's Theorie Analytique des P ()habitues, the most profound investigation of this important subject which has ever been written was first published at Paris in 1812, and again in 1820. with supplements. He died after a short illness, and it has been said that his last words were: "What we know is of small amount; what we do not know is enormous;" hut this has been denied. and it is said that his last words were spoken in the presence of Poisson, his favorite pupil, to whom his family had appealed to get him to speak. Poisson, after saluting him, delivered some news which had been received from Germany by the bureau of longitudes in regard to some verifications by Bess.fl of theo retical discoveries of Laplace upon Jupiter's satellites. He opened his eyes and said, "Man pursues nothing but chimeras, ' and never spoke again.