MAYER, mar, Julius Robert von, Ger man physicist: b. Heilbronn, Wiirtemberg, 25 Nov. 1814; d. there, 20 March 1878. He was educated at the gymnasium in Heilbronn, studied medicine at Tubingen and finished his university studies at Munich and Paris. In 1840 he went to Java as a ship's surgeon, and while there turned his attention to studies of the blood, extending his work to exhaustive in vestigations of animal heat, to which he applied the mechanical theory. Returnine in 1841 to Heilbronn, where for some years he practised his profession, he became deeply engrossed with his scientific labors, and in 1842 published in Liebig's Annalen der Chemie und Pharmacie a preliminary statement of his revolutionary theory of heat, together with his views on the conservation and correlation of energy. Three years later he restated his results in 'Die orgamsche Bewegung in ihrepi Zusammenhange mit dem Stoffwechsel,' at the same time giving a forecast of his theory of the meteoric origin of the sun's heat. Contemporaneously with
Mayer the mechanical theory of heat was worked out independently by J. P. Joule (q.v.) in Eng land, and a controversy arose regarding the priority of discovery. The Royal Society .gave Mayer the Copley medal in 1871, and two years before his death he was ennobled by the king of Wiirtemberg. His collected works appeared in 1867 under the title 'Die Mechanik der Warme' (3d ed.. by i. S. Wevrauch 1893). Consult Weyrauch, 'Robert Mayer' (Stuttgart 1890) ; id., 'Kleinere Schrif ten und Briefe von Robert Mayer' (Stuttgart 1893) ; Gross, 'Robert Mayer and Hermann von Helmholtz' (Berlin 1898) ; Jeutsch, E., 'Julius Robert Mayer ; seine Krank heitgeschichte und die Geschichte seiner Ent deckung) (Berlin 1914).