LEVERRIER, URBAIN JEAN JOSEPH ( 181 1-1877 ) , French astronomer, was born at St. LO in Normandy on March II, 1811. His father made great efforts to send him to Paris, where a brilliant examination gained him, in 1831, admittance to the t cole Polytechnique. The distinction of his career there was rewarded with a free choice amongst the departments of the pub lic service open to pupils of the school. He selected the adminis tration of tobaccos, and gave striking proof of ability in two papers on the combinations of phosphorus with hydrogen and oxygen, published in Annales de Chimie et de Physique (1835 and 1837). The place of teacher of astronomy at the Ecole Polytechnique falling vacant in 1837, it was offered to and accepted by Leverrier, who, "docile to circumstance," instantly abandoned chemistry, and directed the whole of his powers to celestial mechanics. Pur suing the investigations of Laplace, he demonstrated with greater rigour the stability of the solar system, and calculated the limits within which the eccentricities and inclinations of the planetary orbits vary. This remarkable debut excited much attention, and, on the recommendation of F. Arago, he took in hand the theory of Mercury, producing, in 1843, vastly improved tables of that planet. The perturbations of the comets discovered, the one by H. A. E. A. Faye in 1843, the other by Francesco de Vico a year later, were minutely investigated by Leverrier. Recalled once more, by the summons of Arago, to planetary studies, he was this time invited to turn his attention to Uranus. Step by step he advanced to the great discovery which has immortalized his name. Carefully sifting all the known causes of disturbance, he showed that one previously unknown had to- be reckoned with, and on Sept. 23, 1846, the planet Neptune was discerned by J. G. Galle (d. 1910) at Berlin, within one degree of the spot Leverrier had indicated. (See NEPTUNE.) This memorable achievement was greeted with an outburst of public enthusiasm. Academies vied with each other in enrolling Leverrier among their members; the Royal Society awarded him the Copley medal; the king of Denmark sent him the order of the Dannebrog; he was named officer in the Legion of Honour, and preceptor to the comte de Paris; a chair of astronomy was created for his benefit at the Faculty of Sciences ; he was ap pointed adjunct astronomer to the Bureau of Longitudes. On Jan.
3o, 1854, he succeeded Arago as director of the Paris observatory. The institution had fallen into a state of inefficiency and Leverrier placed it on a totally new footing. His uncompromising measures and unconciliatory manner of enforcing them raised a storm only appeased by his removal on Feb. 5, 1870. On the death of his successor Delaunay (1816-1872), he was reinstated by niers, but with authority restricted by the supervision of a council. In the midst of these disquietudes, he executed a task of gigantic pro portions. This was nothing less than the complete revision of the planetary theories, followed by a laborious comparison of results with the most authentic observations, and the construction of tables representing the movements thus corrected. Three weeks after he had affixed his signature to the printed sheets of the theory of Neptune he died at Paris on Sept. 23, 1877. Leverrier's aim was the elaboration of the scheme of the heavens traced out by Laplace in Mecanique celeste, and the discovery of Neptune with which his name is popularly identified was only incidental. He twice received the gold medal of the Royal Astronomical Society, London (1868, 1876).
The Annales de l'Observatoire de Paris, the publication of which was set on foot by Leverrier, contain, in vols. i.—vi. (Memoires) (1855-61) and x.—xiv. (1874-77), his theories and tables of the several planets. In vol. i. will be found, besides his masterly report on the observatory, a general theory of secular inequalities, in which the development of the disturbing function was carried further than had previously been attempted. His planetary and solar tables were adopted by the Nautical Almanac, as well as by the Connaissance des temps.
The memoirs and papers communicated by him to the Academy were summarized in Comptes rendus (1839-76), and the more im portant published in full either separately or in the Conn. des temps and the Journal des mathematiques. That entitled Developpemens sur differents points de la theorie des perturbations (1841), was trans lated in part xviii. of Taylor's Scientific Memoirs.