Lemonnier, Pierre Charles (pyĕr shärl ləmônyāˈ) [key], 1715–99, French astronomer. For many years he was professor of physics at the Collège de France. He studied the moon and the influence of Saturn on the motion of Jupiter, determined the positions of many stars, and conducted extensive research in terrestrial magnetism and atmospheric electricity. He repeatedly saw Uranus and recorded it in his charts before it was recognized as a planet by Sir William Herschel (see under Herschel, family). His brother Louis Guillaume Lemonnier, 1717–99, was a botanist and physicist. He was appointed by King Louis XV head of the botanical garden of the Trianon at Versailles and introduced many plants to French horticulture. His work in physics included the Leyden jar experiment, by which he established that water is one of the best electrical conductors and that the surface area, not the mass, of a conducting body determines its electrical charge. His research on electricity produced by storms confirmed the theories of Benjamin Franklin.
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