James Pollard Espy

Born May 9, 1785, in Washington County, Penn.; died Jan. 24, 1860, in Cincinnati, Ohio. American meteorologist.

Beginning in 1817, Espy worked at the Franklin Institute. In 1843 he became director of the Weather Bureau of the US War Department, where he compiled the first weather maps in the United States. Espy developed the theory of atmospheric convection with allowance for the heat released by the condensation of vapor in clouds. He also proposed the “centripetal” theory of cyclones, an important step in the development of the theory of cyclone formation.