Jean Sylvain Bailly

Jean Sylvain Bailly
Bust of Bailly, by Louis-Pierre Deseine
Born	15 September 1736(1736-09-15) Paris
Died	12 November 1793(1793-11-12) (aged 57) Paris
Nationality	French
Fields	astronomer
Influences	Nicolas de Lacaille

Jean-Sylvain Bailly (15 September 1736 – 12 November 1793) was a French astronomer and orator, one of the leaders of the early part of the French Revolution. He served as the mayor of Paris from 1789 to 1791 and was ultimately guillotined during the Reign of Terror.

Scientific career

Born in Paris, Bailly was the son of Jacques Bailly, a supervisor of the Louvre. As a child he was originally intended for a career in the arts, but he became deeply attracted to science, 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. For such achievements he was elected a member of the French Academy of Sciences in 1763.

Scientific papers

Bailly published his Essay on the theory of the satellites of Jupiter in 1766), an expansion of a presentation he had made to the Academy in 1763. It was followed up in 1771 by a noteworthy dissertation, On the inequalities of light of the satellites of Jupiter. and in 1778, he was elected a foreign member of the Royal Swedish Academy of Sciences.

Bailly also gained a high literary reputation by his Éloges of 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, when Bernard le Bovier de Fontenelle's simultaneous membership of all three Academies was renewed in him. From then on, Bailly devoted himself to the history of science, publishing A history of ancient astronomy in 1775, followed by A history of modern astronomy (3 vols., 1782). Other works include Discourse on the origin of the sciences (1777); Discourse on Plato's 'Atlantide' (1779); and A treatise on Indian and Oriental astronomy (1787). Though his works were "universally admired" by contemporaries, later commentators have remarked that "their erudition was… marred by speculative extravagances."

During the French Revolution

The Revolution interrupted his studies. Elected deputy from Paris to the Estates-General, he was elected president of the Third Estate (5 May 1789), led the famous proceedings in the Tennis Court (20 June), and - immediately after the storming of the Bastille - became the first mayor of Paris under the newly adopted system of the Commune (15 July 1789 to 16 November 1791). One of his actions in this position was to secure, with others, and in the face of threats and ridicule, the passage of a decree of 27 September 1791 (confirmed on 30 November of the same year), which declared Jews to be French citizens, with all rights and privileges. This decree repealed the special taxes that had been imposed on the Jews, as well as all the ordinances existing against them.

The dispersal by the National Guard, under his orders, of the riotous assembly in the Champ de Mars (17 July 1791) made him unpopular, and he retired to Nantes, where he composed his Mémoires d'un témoin (published in 3 vols. by MM. Berville and Barrière, 1821–1822), an incomplete narrative of the extraordinary events of his public life. Late in 1793, Bailly left Nantes to join his friend Pierre Simon Laplace at Melun, but was there recognised, arrested and brought (10 November) before the Revolutionary Tribunal at Paris. On 12 November he was guillotined amid the insults of a howling mob. In the words of the 1911 Encyclopædia Britannica, "He met his death with patient dignity; having, indeed, disastrously shared the enthusiasms of his age, but taken no share in its crimes."

The lunar crater Bailly was named in his honour.

Notes

Works

• ^ a: Essai sur la théorie des satellites de Jupiter, 1766
• ^ b: Sur les inégalités de la lumière des satellites de Jupiter, 1771
• ^ c: Histoire de l'astronomie ancienne, 1775
• ^ d: Histoire de l'astronomie moderne, 1782
• ^ e: Lettres sur l'origine des sciences, 1777
• ^ f: Lettres sur l'Atlantide de Platon et sur l'ancienne histoire de l'Asie, 1779
• ^ g: Traite de l'astronomie indienne et orientale, 1787

Sources

• Chapin, Seymour L. (1970). "Bailly, Jean-Sylvain". Dictionary of Scientific Biography. 1. New York: Charles Scribner's Sons. pp. 400–402. ISBN 0684101149. 
•  Chisholm, Hugh, ed. (1911). "Bailly, Jean Sylvain". Encyclopædia Britannica (11th ed.). Cambridge University Press. 
•  This article incorporates text from a publication now in the public domain: "BAILLY, JEAN-SYLVAIN". Jewish Encyclopedia. 1901–1906. http://www.jewishencyclopedia.com/view.jsp?letter=B&artid=139. 
• Stephens, Henry Morse (1886). A History of the French Revolution. C. Scribner's Sons. http://books.google.com/books?id=cyFBAAAAYAAJ&pg=PA51. Retrieved 1 September 2011. 

Further reading

• Eloges by Merard de Saint Just, Delisle de Salles, Jerome de Lalande and Lacretelle
• A memoir by François Arago, read on 26 February 1844 before the Academie des Sciences, and published in Notices biographiques, t. ii. (1852)
• Delambre, Histoire de l'astronomie au 18^me siecle, p. 735
• Jerome de Lalande, Bibliographie astronomique, p. 730.