Dictionary.net

A Scotch physicist, one of the founders of spectrum analysis; born in Edinburgh, Nov. 1, 1828; died near Drogheda, Ireland, Dec. 19, 1887. He established his scientific reputation with a work on "Radiant Heat" (1858), in which he formulated his discovery of the equality of the emissive and absorptive powers of bodies. Other works include: "Treatise on Heat" (1866; 5th ed. 1888); "Elements of Physics" (1870; 4th ed. 1891); "Conservation of Energy" (1873; 7th ed. 1887). With Professor Tait he published "The Unseen Universe; or, Physical Speculations on a Future State" (1875; 17th ed. 1890).