TROWBRIDGE, John, physicist, born in Boston, Massachusetts, 5 August, 1843. He was prepared for Harvard at the Boston Latin-school, but was graduated at the Lawrence scientific school of that university in 1866. After graduation he was made a tutor, and he continued so until 1869, when he was called to the assistant professorship of physics in Massachusetts institute of technology. In 1870 he returned to Harvard to establish a laboratory course of instruction in physics, out of which has grown the Jefferson physical laboratory, which is now the largest of its kind in the United States. In order to secure this great means for advancing the study of physical science, Professor Trowbridge did much in the way of personal solicitation, and also by publishing, both in journals and as pamphlets, papers upon the necessity of a well-equipped physical laboratory. His original, investigations gained for him in 1873 the degree of S.D. from Harvard, and in 1880 he was made professor of experimental physics. In 1888 he was advanced to the Rumford professorship of the application of science to the useful arts, which chair he still (1888) holds. His scientific work has consisted largely of original investigations conducted under his direction and issued as "Contributions from the Physical Laboratory of Harvard College." His independent researches include papers on "Animal Electricity" (1872), in which he showed that the existence of the so-called muscular electric current had not been proved, although generally accepted at that time. He has devised among other instruments "A New Form of Galvanometer " (1871) ; "A New Induction Coil" (1875); and "A New Form of Mirror Galvanometer" (1876). His later papers have had much to do with electricity, and among his memoirs on this subject is "On Telegraphing without a Cable" (1884) and "Niagara Falls considered as a Source of Electricity" (1885). During 1887-'8 he instituted experiments that have proved the presence of carbon and platinum in the sun, and also a series which indicate the absence of oxygen-lines from the solar spectrum. Professor Trowbridge, in addition to membership in many societies, was secretary of the American academy of arts and sciences in 1879-'84, and in the latter year presided over the physical section of the American association for the advancement of science. Then he delivered a vice-presidential address, on "What is Electricity." which was very rich in suggestions concerning the possibilities of that science. He was a member of the International congress of electricians that met in Paris in 1883, and was a delegate to the United States congress of electricians that convened in Philadelphia in October, 1884. In 1878 he was chosen to membership in the National academy of sciences. Professor Trowbridge was one of the editors of the "Annals of Scientific Discovery for 1869" (Boston, 1870), and since 1879 has been an associate editor of the "American Journal of Science," with charge of the notices on physics. His scientific papers exceed fifty in number, and he has published "The New Physics" (New York, 1884).