LALANDE, JOSEPH JEROME LEFRANCAIS DE (1732-1807), French astronomer, was born at Bourg, on July 11, 1732. His parents sent him to Paris to study law ; but the acci dent of lodging in the Hotel Cluny, where J. N. Delisle had his observatory, drew him to astronomy, and he became the zealous and favoured pupil of both Delisle and Lemonnier. He completed his legal studies, and then went to Berlin to make observations on the lunar parallax in concert with those of N. L. Lacaille at the Cape of Good Hope. The successful execution of his task procured for him, before he was twenty-one, admission to the Academy of Berlin, and the post of adjunct astronomer to that of Paris. He now devoted himself to the improvement of the planetary theory, publishing in 1759 a corrected edition of Halley's tables, with a history of the celebrated comet whose return in that year he had aided Clairault to calculate. In 1762 J. N. Delisle resigned in his favour the chair of astronomy in the College de France, the duties of which were discharged by Lalande for 46 years. His house became an astronomical seminary, and amongst his pupils were J. B. J. Delambre, G. Piazzi, P. Mechain, and his own nephew Michel Lalande. His planetary tables were the best available up to the end of the 18th century, and by his publications in connection with tlae transit of 1769 he won great fame. He is best known, however, as a popularises of astronomy.
The Lalande prize, instituted by him in 1802 for the chief astronomical performance of each year, still testifies to his en thusiasm for his favourite pursuit. He died on April 4, 1807.
See Memoires de l'Institut, t. viii. (1807) (J. B. J. Delambre) ; Delambre, Hist. de l'astr. an siecle, p. 547 ; Magazin encyclo pedique, ii. 288 (I8io) (Mme. de Salm) ; J. S. Bailly, Hist. de l'astr. moderne, t. iii. (ed. 1785) ; J. Madler, Geschichte der Himmelskunde, ii. 141 ; R. Wolf, Gesch. der Astronomie; J. J. Lalande, Bibl. astr. P. 428.