Urbain-Jean-Joseph le Verrier

Urbain-Jean-Joseph Le Verrier

An astronomer and director of the observatory at Paris, born at Saint Lô, the ancient Briodurum later called Saint-Laudifanum, in north-western France, 11 May, 1811; died at Paris, 25 September, 1877. From 1831 the talented youth studied at the Ecole Polytechnique with such success that at the end of his course he was appointed an instructor there. While connected with the school he showed a strong predilection for mathematical studies, above all for such problems as Laplace had so skilfully treated in the "Mécanique céleste". Le Verrier soon received an appointment in the government administration of tobaccos; later he became a professor at the Collège Stanislas at Paris, and finally, in 1646, he was appointed professor of celestial mechanics in the faculty of sciences at the University of Paris. As early as 1839 he published a calculation of the variations of the planetary orbits for the period of time from the year 100,000 b.c. to the year 100,000 a.d., in which he proved by figures the stability of the solar system, which Laplace had only indicated. His calculation of the transit of Mercury of 1845 and of the orbit of Faye's comet demonstrated his ability in that province in which he was soon to gain an almost undreamed-of triumph from the discovery, by means of theoretical calculations, of the planet Neptune. The variations observed in Uranus, up to then the most distant planet known, led him to look for the cause of the disturbance outside of its orbit. His calculations enabled him to specify the very spot in the heavens where the body causing the perturbations in question was to be sought, so that the astronomer Galle of Berlin was able by the aid of his specifications to find the new planet at once upon looking for it, 23 September, 1846. In this way Le Verrier gave the most striking confirmation of the theory of gravitation propounded by Newton. He now became a member of the Academy of Sciences, in 1852 was made a senator, and after Arago's death (1853) was appointed director of the Paris Observatory, a position he held with a short interruption (1870-73) until his death. Under his skilful and prudent administration the observatory made important progress both as to equipment in instruments and, more particularly, as regards preeminent scientific achievements of which Le Verrier was the inspiration. He was the founder of the International Meteorological Institute and of the Association Scientifique de France, being the permanent president of the latter. He also gave careful attention to the geodetic work which was intended to give the most complete presentation possible of the configuration of the earth. The instruments of precision with which, in order to attain this end, he equipped the observers were remarkably complete.

His most important work, however, was the construction of tables representing the movements of the sun, moon, and planets: "Tables du Soleil" (1858); "Tables de Mercure" (1859); "Tables de Vénus" (1861); "Tables de Mars" (1861); "Tables de Jupiter" (1876); "Tables de Saturne" (1876); "Théorie d'Uranus" (1876); "Théorie de Neptune" (1876); "Tables d'Uranus" (1877). All these publications were preceded by theoretical investigations: "Théorie du mouvement apparent du Soleil" (1858); "Théorie de Mercure" (1859); "Théorie de Vénus" (1861); "Théorie de Mars" (1861), etc. Considerations similar to those which led to the discovery of the planet Neptune caused Le Verrier to infer the existence of a planet between Mercury and the sun. But far greater difficulties both were and are here connected with actual discovery than was the case with Neptune. However, Le Verrier on this occasion also showed his masterly skill in handling the various problems of the reciprocal perturbations of the planets and other heavenly bodies, as is shown in his writings on the subject: "Formules propres à simplifier le calcul des perturbations" (1876); "Variations séculaires des orbites" (1876), etc.

With all his erudition Le Verrier was a zealous adherent and true son of the Catholic Church; even as deputy of the Assembly he openly acknowledged and defended his Catholic faith before all the world. He was also a ready speaker, one in no way discomposed by the attacks of opponents, for he knew how by profound and logical statements to convince his hearers quickly. When dying he said in the words of the aged Simeon: "Nunc dimittis servum tuum, Domine, in pace". Those who spoke at the funeral of this remarkable man could truthfully assert that the study of the star-worlds stimulated in him the living belief of the Christian to new fervour. Even in the sessions of the Academy he made no concealment of his faith nor of his childlike dependence on the Catholic Church. When, on 5 June, 1876, he presented to the Academy his completed tables for Jupiter, the result of thirty-five years of toil, he emphasized particularly the fact that only the thought of the great Creator of the universe had kept him from flagging, and had maintained his enthusiasm for his task. He also on this occasion spoke strongly, like his colleague Dumas, against the materialistic and sceptical tendencies of so many scholars. To Le Verrier is due the organization of the meteorological service for France, especially the weather warnings for seaports, by which to-day the weather for the following twenty-four hours can be announced with much probability, a matter of especial importance for agriculture and shipping. The "Annales de l'Observatoire de Paris", published during the administration of Le Verrier, consist of thirteen volumes of theoretical treatises and forty-seven volumes of observations (1800-1876). At the time of his death he was making plans for equipping the observatory with a large new telescope, and it may be that the stimulating influence exerted in this direction contributed not a little to the result that everywhere, particularly in North America, generous-minded patrons appeared who, each in his own land, gave the money necessary to obtain larger instruments. On 27 June, 1889, a statue of the distinguished savant which cost nearly 32,000 francs ($6400), was erected by subscription in front of the observatory where he had laboured for so many years.

FIGUIER, L'année scientifique et industrielle, XXI (Paris, 1877); DENZA, Commemorazione di alcuni uomini illustri nella scienza (Turin, 1877); HEUZEAU, Vade-mecum de l'astronomie (Brussels, 1882); Annuaire (for 1890) published by the Bureau des Longitudes; KNELLER, Das Christentum und die Vertreter der Naturwissenschaft (2nd ed., Freiburg im Br., 1904).

ADOLPH MÜLLER.