MAXWELL, JAMES CLERK British physicist, was descended from the well-known Scottish family of Clerk of Penicuik, and was born at Edinburgh on Nov. 13, 1831. He was educated at the Edinburgh academy the University of Edinburgh (1847-5o), and at Cambridge. In 1854 he took his degree as second wrangler, and shared with the senior wrangler of his year (E. J. Routh, q.v.) the Smith's prize. He held the chair of natural philosophy in Marischal college, Aberdeen (1856-6o), and the chair of physics and astronomy in King's college, London (186o-68). He resigned and retired to his estate of Glenlair in Kirkcudbrightshire. He was summoned from his seclusion in 1871 to become the first holder of the newly founded professorship of experimental physics in Cambridge ; and it was under his direction that the plans of the Cavendish labora tory were prepared. He died at Cambridge on Nov. 5, 1879.
For more than half of his brief life he held a prominent position in the very foremost rank of natural philosophers. His contributions to scientific societies began in his 15th year, when Professor J. D. Forbes communicated to the Royal Society of Edinburgh a short paper of his on a mechanical method of tracing Cartesian ovals. In his 18th year, while still a student in Edin burgh, he contributed two valuable papers to the Transactions of the same society—one of which, "On the Equilibrium of Elastic Solids," is remarkable, not only on account of its intrinsic power and the youth of its author, but also because in it he laid the foundation of one of the most singular discoveries of his later life, the temporary double refraction produced in viscous liquids by shearing stress. Immediately after taking his degree, he read to the Cambridge Philosophical Society a very novel memoir, "On the Transformation of Surfaces by Bending." This is one of the few purely mathematical papers he published, and it exhibited at once to experts the full genius of its author.
About the same time appeared his elaborate memoir, "On Fara day's Lines of Force," in which he gave the first indication of some of those extraordinary electrical investigations which cul minated in the greatest work of his life. He obtained in 1859 the Adams prize in Cambridge for a very original and powerful essay, "On the Stability of Saturn's Rings." From 1855 to 1872 he published at intervals a series of valuable investigations con nected with the "Perception of Colour" and "Colour-Blindness," for the earlier of which he received the Rumford medal from the Royal Society in 1860. The instruments which he devised for these investigations were simple and convenient, but could not have been thought of for the purpose except by a man whose knowledge was co-extensive with his ingenuity. One of his greatest investigations bore on the "Kinetic Theory of Gases." This theory received enormous developments from Maxwell, who in this field appeared as an experimenter (on the laws of gaseous friction) as well as a mathematician. He derived the law of dis
tribution of velocities of the molecules of a gas, which is known as Maxwell's law. He wrote an admirable textbook, the Theory of Heat (1871), and an excellent elementary treatise on Matter and Motion (1876).
But the great work of his life was devoted to electricity. He began by trying to translate the ideas of Faraday into the notation of the mathematicians. A considerable part of this work was ac complished during his career as an undergraduate in Cambridge. His great object, as it was also the great object of Faraday, was to overturn the idea of action at a distance. In 1846 W. Thomson (Lord Kelvin) had treated the resultant electric force at any point as analogous to the flux of heat from sources distributed in the same manner as the supposed electric particles and deduced formulae similar to those which had been deduced from the laws of action at a distance. This paper of Thomson's, whose ideas Maxwell afterwards developed in an extraordinary manner, seems to have given the first hint that there are at least two perfectly distinct methods of arriving at the known formulae of statical electricity. The step to magnetic phenomena was comparatively simple ; but it was otherwise as regards electromagnetic phe nomena, where current electricity is essentially involved.
The first paper of Maxwell's in which an attempt at an admis sible physical theory of electromagnetism was made was com municated to the Royal Society in 1864. But the theory, in a fully developed form, first appeared in 1873 in his great treatise of Electricity and Magnetism. This work was one of the most splendid monuments ever raised by the genius of a single indi vidual. Availing himself of the admirable generalized co-ordinate system of Lagrange, Maxwell showed how to reduce all electric and magnetic phenomena to stresses and motions of a material medium, and, as one preliminary, but excessively severe, test of the truth of his theory, he pointed out that (if the electro magnetic medium be that which is required for the explanation of the phenomena of light) the velocity of light in vacuo should be numerically the same as the ratio of the electromagnetic and electrostatic units. In fact, the means of the best determi nations of each of these quantities separately agree with one another more closely than do the various values of either.
One of Maxwell's last great contributions to science was the editing (with copious original notes) of the Electrical Researches of the Hon. Henry Cavendish. (See CAVENDISH.) His collected works were issued in two volumes by the Cambridge University Press in 1890 ; see Life of James Clerk Maxwell by L.
Campbell and W. Garnett (1882). (P. G. T.)