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MONG English physicists holds a distinguished place for the originality and extent of his experimental researches, the grasp of his subtile and comprehensive inquiries, and the boldness and freedom of many of his speculations.

He was the son of a merchant, and was born in Edinburgh, November 1, 1828. At the age of fourteen he went to the University of St. Andrews, and afterward to that of Edinburgh, from which he graduated. During his college course he paid a great deal of attention to pure mathematics, and is credited with having rediscovered, independently of books, La Grange's method of dealing with the differential calculus. After leaving college he spent four years in a mercantile house, and was for two or three years in Australia; but his father's preference that he should be a merchant did not coincide with his own inclinations, and he at length determined to devote his life to physical science.

On his return from Australia, he was so fortunate as to secure the friendship of the late Principal Forbes, and became his assistant in Edinburgh for three years, 1856-'57-'58.

Dr. Stewart has been Director of the Magnetic Observatory at Kew, where he has made numerous and important magnetical observations in connection with the eminent physicist, Mr. Warren De la Rue. He is Professor of Physics in Owens College, Manchester, a Fellow of the Royal Society of Great Britain, of the Astronomical and Meteorological Societies of London, and of various learned bodies on the Continent and in the United States. He received the degree of LL. D. from Edinburgh University, and in 1868 the Rumford Medal of the Royal Society for his researches in light and heat.

Dr. Stewart has been a very active worker in the scientific field, and is the author of many publications, especially in the branches of meteorology, magnetism, and solar physics, of which the following are the most important:

Papers connected with Heat and Light.—1. An Account of Some Experiments on Radiant Heat, involving an Extension of Prevost's Theory of Exchanges (Transactions of Royal Society, Edinburgh, 1858). 2. Researches on Radiant Heat, Second Series (Transactions of Royal Society, Edinburgh, 1859). 3. On the Light radiated by Heated Bodies (Proceedings of Royal Society, London, 1860). 4. On the Nature of the Light emitted by Heated Tourmaline (Proceedings of Royal Society, London, 1860). 5. Internal Radiation in Uniaxal Crystals (Proceedings of Royal Society, London, 1861). 6. Report on the Theory of Exchanges (British Association, 1862).

Papers connected with Meteorology, Magnetism and Sun-spots.