# Lectures on Ten British Physicists of the Nineteenth Century/Lecture 1

TEN BRITISH PHYSICISTS
JAMES CLERK MAXWELL
(1831-1879)
James Clerk Maxwell was born in Edinburgh, Scotland, on the 13th of November, 1831. His father, John Clerk, belonged to the old family of Clerks of Penicuik near Edinburgh, and he added Maxwell to his name, on succeeding as a younger son to the estate of Middlebie in Dumfriesshire, which had for generations been the home of a Maxwell. Hence it was customary in Scotland to speak of the subject of our lecture as Clerk-Maxwell; but by the world at large the "Clerk" has been dropped; for instance the magnetic unit recently defined in his honor is not denominated a "Clerk" or a "Clerk-Maxwell," but simply a "Maxwell." His father was by profession an advocate, that is, a lawyer entitled to plead before the Supreme Court of Scotland; his practice had never been large and at the date mentioned he had retired to live on his estate. John Clerk-Maxwell was of a family, many members of which were talented, and not a few eccentric; to the latter class he himself belonged. He took an interest in all useful processes, and was successful in extending and improving the stony and mossy land which had become his by inheritance. The mother of James Clerk Maxwell belonged to an old family of the north of England, and was a woman of practical ability.
Glenlair was the name given to the new mansion and improved estate. Here the boy had every opportunity of becoming intimate with the ways of nature. He traversed the ​country with the help of a leaping pole, he navigated the duck pond in a wash tub, he rode a pony behind his father's phaeton, he explored the potholes and grooves in the stony bed of the mountain stream which flowed past the house. He studied the ways of cats and dogs; he watched the transformation of the tadpole into the frog, and he imitated the manner in which a frog jumps. But he attracted attention not so much as an incipient naturalist as a physicist. He had great work with doors, locks and keys, and his constant request was "Show me hoo it doos." He investigated the course of the water from the duckpond to the river, and the courses of the bell-wires from the pulls to the bells in the kitchen, "action at a distance" being no explanation to him. When a very small boy he found out how to reflect the sun into the room by means of a tinplate. He early acquired manual skill by making baskets, knitting elaborate designs and taking part in such other operations as went on around him, whether in the parlor, the kitchen, or on the farm.
Being an only child, young Maxwell made playmates of the children of the workmen on the farm, which had one bad effect; the Scottish dialect became such a native tongue that in after life he could not get rid of the brogue.
His early instruction in the elements of education was received from his mother. She taught him to read, stored his mind with Scripture knowledge, and trained him to look up through Nature to Nature's God. But she died from cancer at the early age of 48, and James was left when nine years old to the sole charge of his father. Education at home under a tutor was first tried, but the result was such that preparations were made to send him to the Edinburgh Academy, one of the best secondary schools of the Scottish metropolis. He entered the Academy in the middle of a term, and his reception by the other boys was not auspicious. His manners were not only rustic but eccentric; he had a hesitation in his speech, and he was clad more for comfort than for fashion. They were all dressed in round jacket and collar, the regulation dress for boys in the public schools of England; he came in a gray ​tweed tunic and frill; and his shoes were made after a peculiar design of his father's with square toes and brass buckles. So at the first recess, when they were all outside, they came about him like bees, and demanded who made his shoes, to which he replied:
They tore his tunic .and frill, and gave him the uncomplimentary nickname of "Dafty." Daft is a Scottish word meaning deficient in sense, or silly. Such was the first reception at public school of the boy who became the greatest mathematical electrician of the nineteenth century, whose electrical work in historical importance has been judged second only to that of Faraday. Had the annoyance to which young Maxwell was exposed been confined to the first few days at school, it might be set down to that disposition to haze newcomers which appears to be part of a boy's nature whether in the Old World or the New; but it was too generally persisted in, with the result that young Maxwell never quite amalgamated with the rest of the boys. There were, however, some exceptional lads who could appreciate his true worth, conspicuous among whom were Peter Guthrie Tait, afterwards Professor Tait, and Lewis Campbell, who became his biographer.
The curriculum at the Academy was largely devoted to Latin and Greek; and young Maxwell made a bad start in these subjects. A want of readiness, corresponding, I suppose, to the hesitation in his speech, kept him down, even in arithmetic. But about the middle of his school career he surprised his companions by suddenly becoming one of the most brilliant among them, gaining high, and sometimes the highest prizes for scholarship, mathematics and English verse composition. At his home in Edinburgh, his aunt's house, he had a room all to himself; it was not a study merely, but a laboratory. There before he had entered on the study of Euclid's Elements at the Academy he made out of pasteboard models of the five regular solids.
​But while still a school boy he achieved a mathematical feat which was much more brilliant. His father was a member of the Scottish Society of Arts and of the Royal Society of Edinburgh, and it was his custom to take his son with him to the meetings, and indeed on visits to all places of scientific and industrial interest. A prominent member of the Society of Arts, Mr. D. R. Hay, a decorative painter, and author of a book First Principles of Symmetrical Beauty read a paper before that Society on how to draw a perfect oval. His method was by means of a string passing round three pegs. Young Maxwell had by this time entered on the study of the Conic Sections, and he took up the problem in his laboratory. He modified the manner of tracing an ellipse by doubling the cord from the tracing-point to one of the foci; the curve then described is the oval of Descartes. He also found out how to do it when twice the distance from one focus plus three times the distance from the other focus is to be constant. Maxwell's father wrote out an account of his son's method, and gave it to J. D. Forbes, then professor of natural philosophy at the University of Edinburgh, and Secretary of the Royal Society of Edinburgh. Both Forbes, and Kelland, the professor of mathematics, approved the paper as containing something new to science; it was read by Forbes at the next meeting of the Society, and is printed in the second volume of the Proceedings under the title "On the description of oval curves, and those having a plurality of foci; By Mr. Clerk-Maxwell, Jr., with remarks by Professor Forbes." The author was then 15 years of age. Next year (1847) he finished the curriculum at the Academy, first in mathematics and in English, and very nearly first in Latin.
He now became a student of the University of Edinburgh. At that time the curriculum in Arts embraced seven subjects: Latin, Greek, Mathematics, Physics, Logic and Metaphysics, Moral Philosophy, English Literature. Maxwell made a selection skipping Latin, Greek, and English Literature. Kelland was the professor of mathematics, Forbes of physics, Sir William Hamilton of logic and metaphysics; under these he studied for two years. To Kelland and Forbes he was already known, ​and the latter gave him the special privilege of working with the apparatus used in the lectures on physics. There was then no well-appointed physical laboratory; any research made was conducted in the lecture room or the room for storing the lecture apparatus. But strange as it may seem, Maxwell appears to have done most work for the class of logic. Sir William Hamilton (that is, the Scottish baronet) was noted for his attack on mathematics as an educational discipline, but he was learned in scholastic logic and philosophy, and he had the power of inspiring his students. It was his custom to print on a board the names of the best students for the year in the order of merit; I recollect seeing on one board the name of James Clerk Maxwell, I think about sixth in the list. About this time George Boole published his Mathematical Analysis of Logic which found in Maxwell an appreciative reader. In his third year at the University, besides continuing his experiments in the physical department, he took Moral Philosophy under Professor Wilson, who wrote much under the name of Christopher North but whose lectures on moral science were characterized by Maxwell as vague harangues; also Chemistry in the department of Medicine, and there, as in Physics, he was privileged to make experiments. The academic session at Edinburgh is short—only six months; the long vacations he spent at Glenlair, where he fitted up a small laboratory in the garret of the former dwelling house. There he studied and experimented on the phenomena of light, electricity and elasticity. As the outcome of these researches he contributed two papers to the Royal Society of Edinburgh, which were printed in the Transactions; one on "The Theory of Rolling Curves," the other on "The Equilibrium of Elastic Solids." During his study at Edinburgh University, Maxwell made great use of the high-class works on mathematics and physics which were to be found in the University Library, acting unconsciously on the advice of his compatriot and subsequent neighbor—Thomas Carlyle.
In sending his son to Edinburgh University it was John Maxwell's intention to educate him for the legal profession—​to become an advocate like himself. But the youth's success as an investigator in mathematics and physics suggested to such friends as Forbes, Kelland, Thomson and Blackburn, a scientific career, and it was Maxwell's own conviction that he was better fitted to grapple with the laws of nature than with the laws of the land. His former school fellow Tait, after studying mathematics and physics for one brief session at the University of Edinburgh, had taken up the regular course of study at the University of Cambridge; and he wished to follow. His father was at length persuaded, with the result that Maxwell became a member of St. Peter's College, Cambridge, at the age of 19. Tait was a member of the same college, now entering on the third and last year of his undergraduate course. Thomson was now a fellow of that college.
The change to Cambridge involved a great discontinuity; and Maxwell by nature loved continuity in all his life and surroundings. The investigator of rolling curves and the compression of solids was now obliged to turn his attention again to the Elements of Euclid, and to finding out by the aid of lexicon and grammar the meaning of a Greek play. But, worse still, he found that his fellow students in Peterhouse had no sympathy with physical manipulations. He had brought with him from his laboratory a pair of polarizing prisms, the gift of the inventor Nicol, pieces of unannealed glass, magnets, jampots, guttapercha, wax, etc.; why he should fool with these things was beyond the comprehension of the young gentlemen who lodged and studied in the same college. At the end of his first year Maxwell migrated to Trinity College, the largest foundation of the University, then governed by Whewell who had a broad interest in all the sciences. Physical experimenting was not then so fashionable at Cambridge as it is now; Newton, indeed, made his experiments on light in Trinity College, but very little had been done since his days. In the college of Newton, Maxwell found not only congenial spirits, but soon came to be looked up to as a leader by a set of admiring followers. During his undergraduate years Maxwell found time to contribute various papers to the Cambridge and ​Dublin Mathematical Journal; he was also elected into the Apostles' Club; so-called from the number of the members; their object was the discussion of philosophical questions.
After passing the Little-go, that is the examination in the preliminary studies, he went into training for the mathematical tripos, placing himself in the care of the great trainer of the day, William Hopkins. Notwithstanding that he turned aside often to his favorite pursuits, he succeeded by sheer strength of intellect in gaining the place of second wrangler; and in the more severe competition for the Smith's prizes he was bracketed equal with the senior wrangler. His rival was Routh, who subsequently became the leading tutor for the mathematical tripos, and in the mathematical world is known as the author of a treatise on Rigid Dynamics. Released from a course of prescribed study and the tyranny of a mathematical trainer, Maxwell rebounded at once to his much-loved researches. The spirit in which he now entered upon his independent career as an investigator may be gathered from an aphorism which he wrote for his own conduct: "He that would enjoy life and act with freedom must have the work of the day continually before his eyes. Not yesterday's work, lest he fall into despair, not to-morrow's, lest he become a visionary not that which ends with the day, which is a worldly work, nor yet that only which remains to eternity, for by it he cannot shape his action. Happy is the man who can recognize in the work of to-day a connected portion of the work of life, and an embodiment of the work of eternity. The foundations of his confidence are unchangeable, for he has been made a partaker of Infinity. He strenuously works out his daily enterprises, because the present is given him for a possession."
His activity took two principal directions optical and electrical. For the former line of investigation he inquired on all sides for color-blind persons, devised an instrument for examining the living retina, which he was specially successful in applying to the dog; read Berkeley's Theory of Vision and that part of Mill's Logic which treats of the relation of sensation to knowledge; perfected his color top and made an ​extended series of observations with it. Maxwell's color top consists of a heavy disk with perpendicular spindle. Sectors of different colored papers can be placed on the disk, and made to overlap more or less; a smaller colored disk can be attached so as to cover the central part only. When the top is made to spin, the reflected colors which succeed one another in position are mixed in the eye, and the mind perceives a uniform color. The angular lengths are adjusted till, if possible, a match is made with the color in the centre; then the color equation is read off.
As regards the electrical line of investigation he had already conceived the idea of making the old mathematical theory of electrical attraction and repulsion, as elaborated by Coulomb and Poisson, harmonize with the method by which Faraday was obtaining splendid results, namely, the consideration of the lines of force in the medium. With this end in view he studied the German and French writers; and in the winter of 1855-56 he published a paper on Faraday's lines of force.
At the age of 24 he gained, after competitive examination, a fellowship from his college. Soon after, the chair of physics (natural philosophy it is there called) in Marischel College, one of the teaching colleges of the University of Aberdeen, Scotland, fell vacant; and Maxwell was advised by his old friend Forbes to become a candidate for the appointment. The suggestion agreed with his own aims as to a career, and he found that his father also approved of it. He sent in his application; and was appointed but not before his father had died. So, in the spring of 1856 he became both the master of Glenlair and the professor of physics in Marischel College, Aberdeen University.
He entered on his teaching work at Aberdeen with great enthusiasm. A professor in the Scottish Universities is free to teach his subject according to the most approved method, and is not bound to bend all energies towards fitting his students for an examination conducted by independent examiners; this feature of his duties Maxwell valued highly. At Cambridge he had taken a share in lectures to workingmen, and at Aberdeen ​he continued the practice. While he was very skillful as an experimenter, he was not so successful as an expositor. He had received no training as a teacher; following the example of his father he was accustomed to present things after a curiously grotesque fashion; his vision was short-sighted; his speech was not free from hesitation; his imagination outran his vocabulary; and he could not easily put himself at the viewpoint of the average student attending his lectures.
During the next year he was married to Katherine Dewar, daughter of the principal of the college and a Presbyterian divine, sister I believe of James Dewar who in recent years has become famous for his investigation of the properties of bodies at temperatures bordering on the absolute zero.
St. John's College, Cambridge, had founded an Adams prize in honor of the discoverer of Neptune, to be awarded to the writer of the best essay on a prescribed subject, and to be open to all graduates of the University. In 1857 the examiners chose for the subject "The motion of Saturn's rings." Maxwell made an elaborate investigation, and his essay carried off the prize.
Galileo in 1610 by means of his small telescope discovered a pair of satellites attached to the planet, one on either side. Huyghens in 1659 resolved the pair of satellites into a continuous ring. Cassini in 1679 resolved the continuous ring into an outer and inner ring. Herschel in 1789 determined the period of rotation of the outer ring. In 1850 a dusky ring within the inner bright ring was discovered by Bond at Cambridge, Mass. Maxwell opens his essay as follows: "When we contemplate the rings of Saturn from a purely scientific point of view, they become the most remarkable bodies in the heavens, except, perhaps those still less useful bodies the spiral nebulæ. When we have actually seen that great arch swung over the equator of the planet without any visible connection, we cannot bring our minds to rest. We cannot simply admit that such is the case, and describe it as one of the observed facts in nature not admitting or requiring explanation. We must either explain its motion on the principles of mechanics ​or admit that, in the Saturnian realms, there can be motion regulated by laws which we are unable to explain." Maxwell then showed that the rings, if either solid or liquid, would break into pieces, and concluded as follows: "The final result of the mechanical theory is, that, the only system of rings which can exist is one composed of an indefinite number of unconnected particles, revolving round the planet with different velocities according to their respective distances. These particles may be arranged in series of narrow rings, or they may move through each other irregularly. In the former case the destruction of the system will be very slow; in the second case it will be more rapid, but there may be a tendency towards an arrangement in narrow rings, which may retard the process." It follows from Maxwell's theory that the inner ring must have a greater angular velocity than the outer ring; and that this is the fact was later shown by Keeler at the Allegheny Observatory.
Aberdeen was the meeting place of the British Association in 1859. William Rowan Hamilton was there, full of his new method of quaternions; also Tait, now professor of mathematics at Belfast, and a disciple of Hamilton's. Maxwell was introduced to Hamilton by Tait. He had doubtless already studied the new method, from which he assimilated many ideas which figure largely in his Treatise on Electricity and Magnetism. At Aberdeen there are two colleges, Marischel College and King's College, each of which had then a Faculty of Arts. An agitation for a change had been in progress for some years; in 1860 it ended in a fusion of the two faculties of arts. The Kings College professor of physics was David Thomson, of whom you doubtless have never heard, yet Thomson was retained, and the gifted Clerk Maxwell was left out. However the Crown gave him compensation in the form of a pension. Just then Forbes resigned the chair of physics at Edinburgh; the two friends Maxwell and Tait were rival candidates, and Tait was successful. The contest did not change their friendship. Maxwell was immediately appointed to the corresponding chair in King's College, London.
​In London his duties were not so congenial as they had been in Aberdeen. The session was much longer, and he was not so free to adopt his own methods, for the college was affiliated to the University of London, which alone had the power of granting degrees. After five years in this office he retired to his own estate. While in London he carried out three important investigations. He had already investigated the mixing of colors reflected from colored papers; he now took up the mixing of pure colors of the spectrum. For this purpose he made a wooden box 8 feet long, painted it black both inside and outside, fitted it with the necessary slits, prisms, and lenses; and, in order to get the necessary sunlight, placed it in the window of the garret of his house. Here he observed the effect of mixing the spectral tints, and his neighbors thought him mad to spend so many hours staring into a coffin.
His investigation of the stability of Saturn's rings introduced to his attention the flight of a countless horde of small solid bodies; from this to the kinetic theory of gases the transition is natural.
The third task was the construction for the British Association of a material ohm, defined as the resistance of a circuit when an electromotive force of one volt sends a current of one weber through it. Maxwell, more than any other man, was the founder of the C.G.S. system of units, which became the basis of that practical system of electrical units which is now legalized in all civilized countries. "Weber" was originally the name for a unit of current. In the last verse of his "Valentine from a male telegraphist to a female telegraphist," Maxwell introduces the newly defined units:
It was eminently appropriate that in 1900 the International Electrical Congress should give Maxwell's own name to the unit of magnetic flux.
​For five years (1865-1870) he lived a retired life at Glenlair, broken by visits to London, Cambridge, Edinburgh, and the Continent. But it was then that he found leisure to complete the great work of his life the Treatise on Electricity and Magnetism, published in two volumes in 1873. The aim of the work is to give a connected and thorough mathematical theory of all the phenomena of electricity and magnetism. He started from the facts observed in Faraday's experiments, and in their light he read the old theory of electric action. This work has served as the starting point of many of the advances made in recent years. Maxwell is the scientific ancestor of Hertz, Hertz of Marconi and all other workers at wireless telegraphy. In the introductory chapter Maxwell remarks that the Earth (which was made the basis of the metric system) is not sufficiently constant either in form or in period of rotation; and advises physicists who may judge their papers worthy of a greater endurance to base their units upon the wave-length and period of some specified molecule. Humor or not, Michelson in this country has actually compared the meter of the archives with the wave-length of a certain ray of light.
Professor Tait gave Maxwell much assistance in the preparation of his great Treatise. He urged him to introduce the Quaternion method; but Maxwell found serious practical difficulties. For one thing Hamilton makes use of the Greek alphabet, and Maxwell found that all the Greek letters had already been appropriated to denote physical quantities. But Maxwell was an intuitionalist, and he never trusted to analysis beyond what he could picture clearly. So he adopted the rather curious middle course. "I am convinced that the introduction of the ideas, as distinguished from the operations and methods of Quaternions, will be of great use to us in all parts of our subject." In this departure we have the origin of the school of vector-analysts as opposed to the pure quaternionists.
In 1870 the Duke of Devonshire, who was Chancellor of the University of Cambridge, signified his desire to build and equip a physical laboratory. The Senate accepted the gift, ​and founded in connection a chair of experimental physics. Sir William Thomson was invited to become a candidate, but declined; Maxwell was invited, and after some hesitation acceded. He was elected without opposition. For some time after his appointment Maxwell's principal work was that of designing and superintending the erection of the Cavendish Laboratory, so-called after the family name of the donor. It was opened in 1874. In the following vacation I visited it, but Maxwell as was his wont, had gone to his country home. His assistant mentioned that the equipment was far from complete, and that they were afraid that the Duke of Devonshire might die before his promise of a complete equipment had been availed of. It was not till 1877 that the equipment was completed.
Soon after (1873) he became Cavendish professor he delivered the famous "Discourse on Molecules" in an evening lecture before the British Association, then assembled in Bradford. Maxwell viewed the doctrine of evolution, or at any rate the extreme consequences deducible from that doctrine, with marked disfavor. This dislike originated in part from his bias as a Christian and a theist, but it rested also on philosophical convictions which he set forth in this address. The conclusion is as follows: "In the heavens we discover by their light, and by their light alone, stars so distant from each other that no material thing can ever have passed from one to another; and yet this light, which is to us the sole evidence of the existence of these distant worlds, tells us also that each of them is built up of molecules of the same kinds as those which we find on earth. A molecule of hydrogen, for example, whether in Sirius or in Arcturus, executes its vibrations in precisely the same time. Each molecule therefore throughout the universe bears impressed upon it the stamp of a metric system as distinctly as does the meter of the Archives at Paris, or the double royal cubit of the temple of Karnac. No theory of evolution can be formed to account for the similarity of molecules, for evolution necessarily implies continuous change, and the molecule is incapable of growth or decay, of generation or destruction. ​None of the processes of Nature, since the time when Nature began, have produced the slightest difference in the properties of any molecule. We are therefore unable to ascribe either the existence of the molecules or the identity of their properties to any of the causes which we call natural. On the other hand, the exact quality of each molecule to all others of the same kind gives it, as Sir John Herschel has well said, the essential character of a manufactured article, and precludes the idea of its being eternal and self existent."
The next year, 1874, a counterblast was delivered by Prof. Tyndall in his address at Belfast, as president of the Association. In it occurs the following passage: "Believing as I do, in the continuity of Nature, I cannot stop abruptly where our microscopes cease to be of use. Here the vision of the mind authoritatively supplements the vision of the eye. By an intellectual necessity I cross the boundary of the experimental evidence, and discern in that Matter which we, in our ignorance of its latent powers, and notwithstanding our professed reverence for its Creator, have hitherto covered with opprobrium, the promise and potency of all terrestrial life." Maxwell was present, and he sent to Blackwood's Magazine verses entitled "Notes of the president's address" in which the different points of the address are hit off very nicely.
After accepting the Cavendish professorship he unfortunately took on hand the work of editing the unpublished electrical researches, made 100 years before, by the Hon. Henry Cavendish, a member of the Devonshire family. The task cost him much time and labor which could have been better spent on his own unfinished projects, one of which was an Experimental Treatise on Electricity and Magnetism.
Mrs. Maxwell was now an invalid, and depended much on his care. In the spring of 1879 he himself began to be troubled with dyspeptic symptoms, especially with a painful choking sensation after eating meat; in the fall he sent for an Edinburgh physician to come to Glenlair, and was then informed that he had only a month to live. To get the best medical attention, he and his wife set out for Cambridge; the worst ​features of his suffering were alleviated, and his intellect remained unclouded to the last. He died on the 5th of November, 1879, having nearly completed the 48th year of his age. It is supposed that he inherited the same disease which had caused the untimely death of his mother. He was buried in Parton churchyard among the Maxwells of Middlebie. He left no descendants. Mrs. Maxwell lingered a few years longer, and she bequeathed the residue of her estate to founding a scholarship for experimental work in the Cavendish Laboratory. In the laboratory there is a bust of its first professor, and what is of greater interest, the collection of the models and apparatus which he made with his own hands. Maxwell's portrait hangs in the dining hall of Trinity College, alongside that of Cayley. He was the founder and benefactor of a Presbyterian Church near his home; there he used to officiate as an elder, and in that church there is now a window in his memory. Since the time of his death his fame has grown immensely, especially in consequence of the wonderful applications made of his electro-magnetic theory. That theory led to the conclusion that the velocity of propagation of electrical disturbances is the same as the velocity of light, that light itself is an electromagnetic phenomenon, and that the ratio of the units of the electro-magnetic and electro-static units is the same as the velocity of light in a vacuum. In 1873 he predicted that in the discharge of a Leyden jar electric waves would be produced in the ether, and in 1879 such waves were detected experimentally by Hertz. As a consequence wireless telegraphy is now possible across the Atlantic Ocean.
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