Joseph Lepaute Dagelet

Joseph Lepaute Dagelet (1751-1788) was a French astronomer, clockmaker and mathematician who accompanied Lapérouse on his scientific circumnavigation, in the course of which he perished. Dagelet's astronomical sightings gave precision to the maps posthumously published in the official Atlas du Voyage de la Perouse (Paris: L'Imprimerie de la Republique, An V, 1797).

Young Dagelet arrived in Paris in 1767, welcomed by his uncles the renowned clockmakers Jean-André and Jean-Baptiste Lepaute, who held the brevet horlogers du Roi. Through his aunt, Nicole-Reine Lepaute, wife of Jean-André, he discovered his aptitude for astronomy. From his arrival until 1772 he studied in the observatory of the Collège Mazarin, where he was guided by Joseph Jérôme Lefrançois de Lalande.

In 1773 he departed for the South Seas with the expedition of Yves Joseph de Kerguelen de Trémarec; on his return he was made professor of mathematics at the École Militaire, Paris.

Dagelet is known particularly for having calculated the distance between the center of Mercury and the Sun and for his map of the solar eclipse of 1778. Dagelet discovered a nova in Sagitta (27-29 July 1783) and was a scientific observer of the balloon ascent of Jacques Alexandre César Charles from the Champ de Mars, Paris, 27 August 1783.

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