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Joseph Jerôme Lefrançais de Lalande

Joseph Jerôme Lefrançais de Lalande (July 11, 1732 - April 4, 1807) was a French astronomer.

He was born at Bourg, in the (département of Ain). His parents sent him to Paris to study law; but as a result of lodging in the Hôtel Cluny, where Joseph Nicolas Delisle had his observatory, he was drawn to astronomy, and became the zealous and favoured pupil of both Delisle and Pierre Lemonnier. Having completed his legal studies, he was about to return to Bourg to practise as an advocate, when Lemonnier obtained permission to send him to Berlin, to make observations on the lunar parallax in concert with those of NL Lacaille at the Cape of Good Hope.

The successful execution of this task obtained for him, before he was twenty-one, admission to the Academy of Berlin, as well as the post of adjunct astronomer to that of Paris. He now devoted himself to the improvement of the planetary theory, publishing in 1759 corrected edition of Halley's tables, with a history of the celebrated comet whose return in that year he had aided Alexis Clairault to calculate. In 1762 Delisle resigned the chair of astronomy in the College de France in Lalande's favour. The duties were discharged by Lalande for forty-six years. His house became an astronomical seminary, and amongst his pupils were JBJ Delambre, Giuseppe Piazzi, P Mechain, and his own nephew Michel Lalande. By his publications in connexion with the transit of 1769 he won great fame. However, his difficult personality lost him some popularity.

Although his investigations were conducted with diligence rather than genius, Lalande's career was an eminent one. As a lecturer and writer he helped popularise astronomy; his planetary tables, into which he introduced corrections for mutual perturbations, were the best available up to the end of the 18th century; and the Lalande prize instituted by him in 1802 for the chief astronomical performance of each year, still testifies to his enthusiasm for his favourite pursuit.

Amongst his works are:

He communicated above one hundred and fifty papers to the Paris Academy of Sciences, edited the Connoissance de temps (1759-1774), and again (1794-1807), and wrote the concludin 2 vols. of the 2nd edition of Montucla's Histoire des mathematique (1802).

See Memoires de I'lnstitut, t. viii. (1807) (JBJ Delambre) Delambre, Hist, de I'astr. au XVIII" siècle, p. 547; Magazin encyclopedique, ii. 288 (1810) (Mme de Salm); JS Bailly, Hist, de I'astr moderne, t. iii. (ed. 1785); J Madler, Geschichte der Himmelskunde ii. 141; R Wolf, Gesch. der Astronomie; JJ Lalande, Bibl. astr p. 428; JC Poggendorff, Biog. Lit. Handworterbuch; M Marie Hist, des sciences, ix. 35.

This entry was originally from the 1911 Encyclopedia Britannica.