Rowland, Henry Augustus (rōˈlənd) [key], 1848–1901, American physicist, b. Honesdale, Pa., grad. Rensselaer Polytechnic Institute, 1870. He was professor of physics at Johns Hopkins from 1875. Rowland is known especially for his invention of a dividing engine for ruling diffraction gratings on curved surfaces and for accurately determining the value of the ohm and the mechanical equivalent of heat. He also did important work in the field of electrical power.
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