Espy, James Pollard (ĕsˈpē) [key], 1785–1860, American meteorologist. He developed a convection theory of storms, explaining it in 1836 before the American Philosophical Society and in 1840 before French and British scientific societies; his Philosophy of Storms was published in 1841. He became meteorologist to the War (1842) and Navy (1848) departments and developed the use of the telegraph in assembling weather observation data by which he studied the progress of storms and laid the basis for scientific weather forecasting.
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