The Cambridge History of English and American Literature in 18 Volumes (1907–21).
Volume XIV. The Victorian Age, Part Two.
§ 15. James Clerk Maxwell
We have next to mention one whose work has had so important an influence on the subsequent growth of the subject as to make it the beginning of a new epoch. This was James Clerk Maxwell—the most modest of men—another member of the Cambridge school, who, for the last eight years of his life, occupied in the university the then newly created chair of experimental physics.
Since the time of Descartes, natural philosophers had never ceased to speculate on the processes by which gravity, light and electricity are transmitted through space. So far as electricity is concerned, the idea of lines of force in a continuous medium is due to Faraday. Kelvin, as a young man, had suggested that electric force might be transmitted through a medium, somewhat as elastic displacements are transmitted through an elastic solid. This idea was taken up by Maxwell, who, in 1856, elaborated the analogies offered by the flow of a liquid, and, five years later, devised a mechanical model of electro-magnetic action. He now brought forward a series of arguments to show that an electric current was a phenomenon of translation, magnetism one of rotation and the electrostatic state one of strain of the ether. These conclusions led him to assert that light consists of transverse waves of the same medium as that required for the explanation of electric and magnetic phenomena. On this theory, all currents are closed; magnetic energy is the kinetic energy of the ether, and electric energy the energy of strain of the ether. These views were presented, as a whole, in 1864. Further extensions and developments of the theory followed, and the whole was set out in his treatise published in 1873. This celebrated work is far from easy to read, and the exposition is not systematic, but it may be said that the fundamental ideas are now universally accepted, and most of the work of his successors has been built on the foundation here laid. The theory was based on Faraday’s ideas; but it required a trained mathematician to give the final form to his conceptions and to deduce their consequences. Hence, the theory is properly associated with Maxwell’s name. Maxwell, also, took a considerable part in framing a standard system of electrical measurements. He contributed largely to the kinetic theory of gases, and, incidentally, to theories on the constitution of matter.
A large part of the history of mathematical physics during the last quarter of the nineteenth century consists of the completion and extension of Maxwell’s electromagnetic theory. No inconsiderable part of this is due to his successors at Cambridge, and to describe recent researches in physics without mentioning the names of lord Rayleigh, Sir Joseph John Thomson and Sir Joseph Larmor is almost impossible; here, however, we must content ourselves with a very brief account of the general line of investigation followed in the last part of the period covered by the present section.
It has already been pointed out that Maxwell’s exposition of his electromagnetic theory of light was neither systematic nor complete. A curious omission in it was the absence of any explanation of reflection and refraction; this was supplied by Helmholtz. The problem of the effects produced by the translation of electric charges, raised by the same investigator, was solved by the researches of the present Cavendish professor at Cambridge, George Francis FitzGerald of Dublin, and others: in the mathematical development of the theory, which now proceeded apace, they, again, took a prominent part. In 1883, FitzGerald explained a system of magnetic oscillators by which radiant energy could be obtained from electrical sources, thus confirming Maxwell’s theoretical conclusion that light was an electromagnetic phenomenon. Some of Maxwell’s assumptions on which he had based his theory still remained unconfirmed; but, a year or two later, the theory was placed on a firmer experimental basis by Hertz. The results, incidentally, led to the introduction of wireless telegraphy.
The question of the conduction of electric discharges through liquids and gases had been raised by Faraday. It was now taken up seriously, and various types of rays, cathode rays, Röntgen rays, etc., were discovered. These researches led to new views on the constitution of matter. The investigations began with a theory of electrons, and, finally, led to the view that every so-called atom is formed by a combination of two elements in varying proportions, and that, possibly, these two elements are to be identified with forms of electricity—one of the most far-reaching hypotheses propounded in recent times.
The efforts to extend the theory of the electromagnetic field to cases where heavy masses are in motion introduces the difficult question as to whether the ether round and in bodies is affected by their motion, and to this theory of relativity much attention is now being paid.
One of the striking features of the Victorian period has been the equipment of large laboratories where experments can be carried out by students with an accuracy wholly impossible in former days. Two of the earliest of these were built at Oxford and Cambridge, the former known as the Clarendon laboratory in 1872, the latter, known as the Cavendish laboratory, being the gift of the seventh duke of Devonshire. In the latter, Clerk Maxwell taught and has been succeeded by professors not less distinguished. The existence of such laboratories in seats of learning has profoundly affected the teaching of the subject by training large numbers of competent observers, besides calling forth in ever widening circles an intelligent interest in physical studies.
It is not, we think, too much to say that the work in physics of the Victorian period has completely revolutionised the subject, and, both on its theoretical and practical sides, far exceeds in value that previously done in any period of similar extent. The theory of gravitation was the great achievement of the Newtonian school. In the following century, physical optics and, later, the nature of ether attracted most attention from philosophers, while practical men developed the steam-engine and studied the theory of heat. The Victorian age has seen electricity raised to the rank of an all-embracing science, and applied to innumerable industrial uses—power-engines, lighting, heating, telegraphy, telephones. Other important scientific and industrial applications relate to photography and spectrum analysis; the development of the turbine-engine; the invention of the internal combustion-engine, with its numerous uses in transport on land and water; the introduction of submarine boats, and heavier-than-air flying-machines; and the use of wireless telegraphy. In this chapter, however, a bare reference to these practical applications must suffice.