Reference Work Entry

Biographical Encyclopedia of Astronomers

pp 1120-1121

Date:

Jeaurat, Edme-Sébastien

Born Paris, France, 14 September 1724

Died Paris, France, 8 March 1803

Edme Jeaurat was an observational astronomer and an editor of the Connaissance des temps. He was the son of an engraver of the king, his mother the daughter of Sébastien Leclerc. Etienne Jeaurat, his uncle, who would become a painter for the queen, taught Jeaurat to draw. A friend of the family, Lieutaud, astronomer of the Académie des sciences, taught him mathematics. Thanks to his artistic training, Jeaurat received a medal from the Academy of Painting at the age of 22 and, in 1750, published an “Essai de perspective à l’usage des artistes.”

But Jeaurat was now more interested in mathematics than in drawing. In 1749, as a geographer-engineer, he worked on the Carte de France project under the direction of César Cassini de Thury . In 1753 he was appointed teacher of mathematics at the Military School, then in a temporary establishment at Vincennes. There he met Joseph-Jérôme Lalande , who steered him to astronomy.

Jeaurat’s first observation was that of comet 1P/Halley. In 1760 he founded the first observatory of the Military School recently established at the Champ de Mars, Paris. It was a wooden building, rather fragile above a mansarde, where he had several instruments, including a heliometer with an 18-ft focus, with which he observed the oppositions of Jupiter and Saturn. In 1763, Jeaurat and Jean Bailly were in competition to enter the Académie des sciences, but both were named, Jeaurat as a supernumerary astronomer, then geometer, and Bailly as an astronomer. Jeaurat later became an associate and finally a pensioner in 1785.

In 1766 Jeaurat published new tables of Jupiter along with Bailly’s theory on satellites. A second observatory with one story was built for him at the Military School; it had a small platform and a round room with a roll-off roof. Jeaurat moved his instruments there in May 1769 and observed the transit of Venus on 3 June 1769. The following year he left this observatory and moved into lodgings at the Royal Observatory, vacant since Jean Chappe dAuteroche died in California (Mexico). There he made a few observations of the planets and eclipses until 1787.

In 1772, Lalande, having been become a pensioner of the academy, resigned as editor of the Connaissance des temps. Jeaurat succeeded him and continued the changes inaugurated by his predecessor in 1760. Jeaurat published 12 volumes, covering the years from 1776 to 1787, including data such as Tobias Mayer ’s zodiacal catalog, James Bradley ’s observations, the positions of Parisian steeples, and Charles Messier ’s great catalog of nebulae. When Jeaurat himself became a pensioner, he handed the editorial duties to Pierre Méchain . During this period Jeaurat published a few works on optical instruments: for example, he described in 1778 a refracting telescope with a double image, later fabricated by the optician Navarre. When the rebuilding of the vaults of the Paris Observatory began in 1787, Jeaurat had to leave. He became assistant director, then director, of the academy in 1791/1792. With the suppression of the academies during the Revolution (1793), he lost his pension and his savings. In 1794, Jeaurat wrote on behalf of his observatory colleagues to defend their good citizenship. He was elected to the astronomy section of the Institut de France in December 1796, after the death of Alexandre Pingré . Jeaurat then moved back to the observatory and was allowed to remain there, by the Bureau des longitudes, until his death.

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