Jacques Charles, in full Jacques-Alexandre-César Charles, (born November 12, 1746, Beaugency, France—died April 7, 1823, Paris), French mathematician, physicist, and inventor who, with Nicolas Robert, was the first to ascend in a hydrogen balloon (1783). About 1787 he developed Charles’s law concerning the thermal expansion of gases. From clerking in the finance ministry Charles turned to science and experimented with electricity. He developed several inventions, including a hydrometer and…
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