Walter Rogers Johnson, an American physicist, born in Leominster, Mass., June 21, 1794, died in Washington, April 26, 1852. He graduated at Harvard college in 1819, and in 1821 became principal of the academy at German-town, Pa. In 1826 the Franklin institute established a high school in Philadelphia, to give the industrial classes cheap instruction in sciences and arts, according to a plan of Mr. Johnson, and gave him the chair of mechanics and natural philosophy. He added to his instructions a public course of lectures on mechanics and philosophy, under the direction of the institute, which were largely attended by both sexes. In 1836 he commenced a series of geological investigations, with special reference to the coal formations and iron ores of Pennsylvania. In 1837 he was appointed to take charge of the department of magnetism, electricity, and astronomy in the United States exploring expedition, but he resigned owing to changes of the original plan. In 1839 he was appointed to the chair of chemistry and physics in the medical department of the university of Pennsylvania. In 1843 he entered upon a course of investigations, under the authority of congress, into the character of the different varieties of coal, and their absolute and relative values for generating steam and heat and producing illuminating gas, of which a report was published in 1844. He subsequently made scientific researches on other subjects connected with the navy department; and in 1845, under appointment of the city authorities of Boston, he examined the sources from which a supply of pure water might be brought to that city.

He participated in the organization of the American association of geologists, and, at its subsequent reorganization as the American association for the advancement of science, was its first secretary.