Makers of Electricity

by Brother Potamian; James J. Walsh

While we think of Maxwell as a mathematical physicist, it must not be forgotten that he was also one of the leading experimental scientists of that great epoch, the nineteenth century. Only a man who was himself a great experimenter could have properly appreciated and developed, from the mathematical standpoint, the works of such men as Cavendish and Faraday. From his early years, Maxwell displayed a distinct fondness for experimentation, and this even extended to experiments upon himself. In many ways this trait of his would remind us of Johann Müller, the great father of modern German medicine.[31] Like Müller, there was danger also of Maxwell's experiments on himself getting him into trouble. For instance, at one time his love of experiment led him to try sleeping in the evening and getting up to work at midnight, so as to have the long, silent hours of the night to himself. In the sketch of his life by Dr. Garnett,[32] a letter from one of his friends is quoted with regard to this nocturnal habit, which is amusing as well as interesting. The friend wrote:

"From 2 to 2:30 a. m. he took exercise by running along the upper corridor, down the stairs, along the lower corridor, then up the stairs, and so on until the inhabitants of the rooms along his track got up and laid perdus behind their sporting doors, to have shots at him with boots, hair-brushes, etc., as he passed." His love of fun, his sharp wit, his extensive knowledge, and, above all, his complete unselfishness, rendered him a universal favorite, in spite of the temporary inconveniences which his experiments may have occasionally caused to his fellow-students.

In 1857, Clerk Maxwell received the Adams Prize for his essay on "The Stability of the Motion of Saturn's Rings." He shows very clearly that these annular appendages consist of a large number of small masses. This work would seem to be very distant from anything that Maxwell had attempted before, and would indeed seem to the superficial observer, at least, to be quite out of his sphere. It was the mathematics of it that attracted him, and the fact that the problem was difficult, indeed, one of the most difficult at that time before astronomers, only added zest to his resolve to fathom it. All his life, mathematics continued to be his favorite form of work, and his power to express the most complex physical phenomena in mathematical formulæ gave him a reputation throughout Europe unsurpassed by anyone of his generation. The more a problem seemed incapable of direct statement in mathematical terms, provided it represented a great occurrence in nature, the more Maxwell was attracted to it; and the training of these early years in thus setting mathematics to the solution of physical relations, was to serve him in good stead when he came to try his hand at demonstrating the meaning of electricity in mathematical terms.

Just before this, in 1856, Maxwell, though only twenty-five years of age, was offered the chair of natural history, which included most of the physical sciences, at Marischal College, Aberdeen. With the attention that his mathematical papers attracted, it is not surprising that after four years of teaching experience he was invited to King's College, London. He held his new position for eight years, and then his health required him to retire to his estate in Kirkcudbrightshire. After three years of retirement, his English Alma Mater demanded his services, and the temptation to get back to an academic career was so great that he could not resist it. He became, in 1871, Professor of experimental physics at Cambridge. To him, more than to anyone else, is due the magnificent development of the physical sciences which took place at Cambridge during the last quarter of the nineteenth century. Unfortunately, he was not destined to live to enjoy the fruits of his labor in organizing the scientific side of the university, but it was under his direction that the plans of the Cavendish Laboratory were prepared, and he superintended every step of the progress of the building. It was under his careful management, too, that the purchase of the very valuable collection of apparatus, with which it was equipped by the Duke of Devonshire, was made, and Maxwell's work here counts for much in the history of English science.

He died in 1879, when only forty-eight years of age, but he had deeply impressed himself upon the science of the nineteenth century. For quite one-half of his scant half-century span of life he had occupied a prominent place in England, and after the age of thirty-five had come to be generally recognized as one of the leading physical scientists of the world. His career is, as we have said, a striking illustration of how early in life a man's real work is likely to come to him, and how little success in original investigation is dependent on that development of mind which is supposed to be due only to long years of application to a particular branch of study. Manifestly it is the original genius that counts for most, and not any training that it receives, except such as comes from its own maturing powers. Environment, if unfavorable, does not hamper it much, nor keep it from reaching the proper terminus of its destiny; and poor health only serves to prevent the exercise of its full powers, but does not eclipse the manifestation of its capacity.

Clerk Maxwell's important contribution to science was the demonstration that electro-magnetic effects travel through space in the form of transverse waves similar to those of light and having the same velocity. We have become so familiar with the ideas contained in this explanation, that they seem almost obvious now. They came, however, as a great surprise to Clerk Maxwell's generation, and at first seemed to be merely a theoretic expression of a mathematical formula. Not long afterwards, however, Maxwell's explanation was corroborated by Hertz, who showed that these waves were propagated just as waves of light are, and that they exhibit the phenomena of reflection, refraction and polarization. Hertz went on from his demonstration of the actuality of Maxwell's mathematical theory to the demonstration of further electrical waves. These Hertzian waves, as they were called, were a startling discovery, but remained only a scientific curiosity until they were taken advantage of for wireless telegraphy, when a new era of applied electrical science began.

How his success in this was accomplished will be best understood from Prof. Guthrie Tait's account of Maxwell's devotion to electricity as a life-work. He says:

"But the great work of his life was devoted to electricity. He began by reading with the most profound admiration and attention the whole of Faraday's extraordinary self-revelations, and proceeded to translate the ideas of that master into the succinct and expressive notation of the mathematicians. A considerable part of this translation was accomplished during his career as an undergraduate in Cambridge. The writer had the opportunity of perusing the MS. on Faraday's lines of force, in a form little different from the final one, a year before Maxwell took his degree. His great object, as it was also the great object of Faraday, was to over-turn the idea of action at a distance. The splendid researches of Poisson and Gauss had shown how to reduce all the phenomena of statical electricity to mere attractions and repulsions exerted at a distance by particles of an imponderable on one another. Sir W. Thomson had, in 1846, shown that a totally different assumption, based upon other analogies, led (by its own special mathematical methods) to precisely the same results. He treated the resultant electric force at any point as an analogous flux of heat from the sources distributed, in the same manner as the supposed electric particles. 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 formulæ of statical electricity. The step to magnetic phenomena was comparatively simple; but it was otherwise as regards electromagnetic phenomena, where current electricity is essentially involved. An exceedingly ingenious, but highly artificial, theory had been devised by Weber, which was found capable of explaining all the phenomena investigated by Ampère as well as the induction currents of Faraday. But this was based upon the assumption of a distance-action between electric particles, whose intensity depended upon their relative motion as well as on their position. This was, of course, more repugnant to Maxwell's mind than the statical distance-action developed by Poisson. The first paper of Maxwell's in which an attempt at an admissible physical theory of electromagnetism was made, was communicated to the Royal Society in 1867. But the theory in a fully developed form, first appeared in his great treatise on Electricity and Magnetism (1873). Availing himself of the admirable generalized coördinate system of Lagrange, Maxwell has shown 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 this theory has shown that, if the electromagnetic 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. We do not as yet certainly know either of these quantities very exactly, but the mean values of the best determination of each separately agree with one another more closely than do the various values of either. There seems to be no longer any possibility of doubt that Maxwell has taken the first grand step towards the discovery of the true nature of electrical phenomena. Had he done nothing but this, his fame would have been secure for all time. But, striking as it is, this forms only one small part of the contents of his truly marvelous work."

Maxwell's prediction as to the propagation of electric waves has received its full confirmation, as we have said, in the brilliant experiments of Hertz, and in the subsequent application of the Hertzian waves to wireless telegraphy in our own time. It was not by mere chance that this development of Maxwell's thinking came. Hertz himself declared, in the introduction to his collected papers, that he owed the suggestion of his work to Faraday and Maxwell, and above all to Maxwell's speculations as to the nature of electricity and its relations to light. Hertz said:

"The hypothesis that light is an electric phenomenon is thus made highly probable. To give a strict proof of this hypothesis would logically require experiments upon light itself. There is an obvious comparison between the experiments and the theory, in connection with which they were really undertaken. Since 1861, science has been in possession of a theory which Maxwell constructed upon Faraday's views, and which we therefore call the Faraday-Maxwell theory. This theory affirms the occurrence of the class of phenomena here discovered, just as positively as the remaining electric theories are compelled to deny it. From the outset, Maxwell's theory excelled all others in its elaboration and in the abundance of relations between the various phenomena which it included."