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Jean Sylvain Bailly

French astronomer, mathematician, freemason, and political leader (1736–1793)

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Through French Revolution and Astronomy

Scientific career

Born in Paris, Bailly was the son of Jacques Bailly, an artist and supervisor of the Louvre Palace, and the grandson of Nicolas Bailly, also an artist and court painter. As a child he originally intended to follow in his family's footsteps and pursue a career in the arts. He became deeply attracted to science, however, particularly astronomy, by the influence of Nicolas de Lacaille. An excellent student with a "particularly retentive memory and inexhaustible patience", he calculated an orbit for the next appearance of Halley's Comet (in 1759), and correctly reduced Lacaille's observations of 515 stars. He participated in the construction of an observatory at the Louvre. These achievements along with others got him elected to the French Academy of Sciences in 1763. In the years prior to the French Revolution, Bailly's distinctive reputation as a French astronomer led to his recognition and admiration by the European scientific community. Due to his popularity amongst the scientific groups, in 1777, Bailly received Benjamin Franklin as a guest in his house in Chaillot.

Scientific and other writing

Bailly published his Essay on The Theory of the Satellites of Jupiter in 1766.a The essay was an expansion of a presentation he had made to the academy in 1763. He later released the noteworthy dissertation On the Inequalities of Light of the Satellites of Jupiterb in 1771. In 1778, he was elected a foreign member of the Royal Swedish Academy of Sciences.

Bailly gained a high literary reputation thanks to his Eulogies for King Charles V of France, Lacaille, Molière, Pierre Corneille and Gottfried Leibniz, which were issued in collected form in 1770 and 1790. He was admitted to the Académie française on 26 February 1784 and to the Académie des Inscriptions in 1785. From then on, Bailly devoted himself to the history of science. He published A History of Ancient Astronomy c in 1775, followed by A History of Modern Astronomy (3 vols., 1782).d Other works include Discourse on the Origin of the Sciences and the Peoples of Asia (1777),e Discourse on Plato's 'Atlantide' (1779),f and A Treatise on Indian and Oriental Astronomy (1787).g Though his works were "universally admired" by contemporaries, later commentators have remarked that "their erudition was... marred by speculative extravagances."

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