Laplace, Pierre Simon

la-plass, Pierre Simon (1749-1827), a French mathematician and astronomer. He was a native of Normandy. His father was a peasant farmer of small means. Laplace was educated by persons of means who recognized his genius. He gained a position first as a teacher of mathematics in a military school. He wrote a letter on the principles of mechanics to one in authority,' and secured an appointment as professor of mathematics in the Military School of Paris. This position gave him opportunity for study and investigation. He is called sometimes the Newton of France. Though Laplace is considered one of the most brilliant scientists the world has known, his discoveries are of interest to the astronomer rather than to the public. He investigated, for instance, the irregularities in the movements of the planets. The attraction of planets for each other draws them out of their courses slightly. Through the influence of the one on the other, Jupiter and Saturn, for instance, leave their courses by half a degree. There were astronomers who predicted that sooner or later collisions would occur, and that our planetary system would go to ruin. Laplace, cooperating with a friend of nearly equal note, Lagrange, established the fact that, although the planets get out of their orbits slightly, they accomplish their trips with mechanical regularity. Even the variations can be computed with exactness, and are completed with fixed cycles of years. The perturbations, as they are called, of Jupiter and Saturn run through a period of 913 years, at the end of which time these planets are exactly where they began. A similar period of disturbances between Uranus and Neptune is completed in each 4,000 years. The sum and substance of Laplace's announcement is that the world may rest easy. There is no danger of a clash between the different members of the solar system. His greatest work, Celestial Mechanics, appeared in 1799-1825. It has been translated into English. The fame of Laplace as a scholar brought him an appointment as minister of the interior. His incapacity was such that Napoleon dismissed him at the end of six weeks with the remark that he was trying to run France on the principles of infinitesimal calculus. He was a member of the French Academy. His life was free from the poverty and worry that has overtaken many eminent scholars. His name is associated prominently with a theory of the solar system known as the Nebular Hypothesis. See Astronomy; Nebular Hypothesis