Faraday, Maxwell, and the Electromagnetic Field Read online

  John's grandfather was the first Clerk Maxwell to be laird of Middlebie, but he never lived there, and when he suffered heavy losses from mining investments, most of the vast estate had to be sold, leaving a 1,500-acre residue. This passed to John's father, but he joined the British East India Company's navy and never lived at Middlebie either. When John came into the inheritance while still at school, Middlebie was, to the family, no more than a primitive outpost, and it seemed that he, too, would be an absentee landlord. He grew up in sophisticated Edinburgh society and became a lawyer but never pursued the profession with much vigor. With an adequate private income he could afford to indulge a passion for science and engineering. He enjoyed keeping abreast of the latest ideas, which might be on anything from water-treatment plants or mining technology to the mass production of teapots, and he acquired a wide circle of like-minded friends in industry, agriculture, and universities. With his closest friend, John Cay, he tried to invent and market various useful new devices, such as a bellows that would supply a continuous, steady blast. These plans came to nothing, but another began to form in his mind—to go to live at Middlebie and there apply his modern ideas on forestry and farming. Perhaps that, too, would have gone the way of other “best-laid schemes o’ mice an’ men,” had his long friendship with John Cay's sister Frances not blossomed into love.1 Frances was a resolute woman who supplied the get-up-and-go that he had so far lacked. She agreed to marry him, and they decided to make their life together in Galloway.2

  It was a herculean project. The estate had been long neglected, and much work was needed, such as clearing scrub and stones, before plowing and planting could begin. There was no suitable dwelling at Middlebie, but that didn't matter—to John, the prospect of designing and building his own house was irresistible. He drew up plans for a grand mansion, but ground clearing had eaten deep into the project budget and they could only afford to build one section—the rest would have to wait. The Clerk Maxwells brought new life to Middlebie, and their new house, though small, was at its heart. They called it Glenlair, and the name soon came to be applied to the whole estate.

  Frances gave birth to a daughter, Elizabeth, but joy changed to anguish when the baby died. When Frances became pregnant again, they decided to go to Edinburgh for the birth, to be near relations and a hospital if needed. This time it was a boy—James Clerk Maxwell was born on June 13, 1831. There were joyful celebrations with relations in Edinburgh, but Glenlair soon drew them back. It was now a family home, a wonderfully happy one for their son, and they watched over his development with indulgent devotion.

  He soon showed himself to be a remarkable child. Nothing that went on escaped his attention. All parents have to answer incessant questions, but to be interrogated by young James was an experience of a different order. Anything that moved, shone, or made a noise drew the question “What's the go o’ that?” and if the answer didn't satisfy him, he'd follow up with “but what's the particular go of it?”3 In a letter to her sister, Jane, in Edinburgh, Frances describes James at age three:

  He is a very happy man…he has great work with doors, locks, keys, etc., and “Show me how it doos” is never out of his mouth. He also investigates the hidden courses of streams and bell-wires…and he drags papa all over to show him the holes where the wires go through.*

  Recalling her own visits to Glenlair, Aunt Jane used to remark fondly that it was humiliating to be asked so many questions she couldn't answer by such a young child. He quickly learned to read and found that books not only answered some of his questions but were a delight besides; Shakespeare and Milton became particular favorites. There was the Bible, too; religion was important, and family prayers were part of the daily routine. He insisted on having a go at household chores, taking a hand with baking and basket making, and every morning helping Sandy, the gardener and handyman, to fetch water by cart from the river. Most of James's time, though, was spent in the surrounding countryside, where the rocks, the woods, the river, and the creatures that lived all around were endless sources of fascination. He ran around with the estate children, learned their Galloway speech, and acquired a local accent that remained with him all his life.

  There were no formal trappings in the Clerk Maxwell household, and James had a much-closer relationship with his parents than was usual among the gentry. His mother was his tutor, and his father often took him along on local business, chatting as though to a younger brother. John Clerk Maxwell was now well known and well liked in the Happy Valley, as the Vale of Urr was known to its residents, and an observer has left us a picture of him as he must have appeared to all who knew him:

  While…unostentatious and plain in all his ways, he was essentially liberal and generous. No one could look in his broad face beaming with kindliness and think otherwise…. By his ever-wakeful consideration he breathed an atmosphere of warm comfort and quiet contentment on all (including the dumb animals) within his sphere.

  James came to understand his father's grand project, which was to go on improving the estate and the lives of all who lived there—and later took it on as his own. The Clerk Maxwells took a full part in the Happy Valley social life; there were dances and fairs, and, in the summer, picnics and archery. Life at home was busy yet harmonious and relaxed, and it hummed with jokes and gently irreverent banter—no person or institution was above some amiable debunking. The spirit of these times stayed with Maxwell all his life—he always loved a joke, and more straitlaced colleagues sometimes failed to see that a remark was meant in jest.

  The idyll came to an end when James was eight years old. Frances was diagnosed with stomach cancer and, after enduring an excruciating operation without anesthesia, she died at the age of forty-seven. The family had lost its hub. Father and son were desolate, but grief drew them still closer together. Bound by the strongest of ties, the first thoughts of each were always for the other, even when they were miles apart in later years.

  Maxwell's parents had originally planned for him to be home schooled until he was thirteen, when he would go straight to university, but his father was too busy with the estate and other local business to take on a tutorial role. There were no suitable schools within daily traveling distance, and John couldn't bear the thought of sending his son—his closest companion—away. James needed a new tutor, and John decided to engage a sixteen-year-old boy from the neighborhood. It was a disastrous choice. The tutor used the methods by which he had himself been taught—rote learning accompanied by physical chastisement—and it was agony for young James. Not wanting to disappoint his father, he endured the ear pulling and cuffs about the head without complaint, but nothing could induce him to learn by mechanical recitation. After a year of torment, he rebelled by rowing himself in a tub to the middle of a duck pond and refusing to come in. Aunt Jane happened to visit at about this time and was quick to realize what had been going on. Action followed promptly: the tutor was sent away and James was booked in to start at the Edinburgh Academy, one of the best schools in Scotland. John's sister, Isabella, lived only a short distance from the school, as did Jane herself, so James could stay with one or other of his aunts in term time and John could visit whenever time could be spared for the two-day coach journey from Glenlair.

  James joined a class of sixty boys who had already spent more than a year at the school and developed their own pack culture. Any new boy was in for a hard time, and when this one arrived wearing a bizarre tunic and clumpy, square-toed shoes, their hostile curiosity knew no bounds. He seemed to be some kind of peasant from a far-off land, and he even spoke with a curious accent. They baited him unmercifully, and he walked home to Aunt Isabella's at the end of his first day with clothes in tatters.

  The clothes were the ones he wore at Glenlair, specially designed for comfort and practicality by his father, who had done some of the tailoring and cobbling himself. Though a sagacious man in so many ways, John was prone to extraordinary lapses of judgment. Aunts Isabella and Jane promptly put this one right by seeing that the
boy was properly attired for school, but the taunting went on. James bore it all with remarkable good humor, only once turning on his tormentors when goaded beyond endurance. Such bravery and composure commanded respect, and he gained a degree of acceptance. But he didn't think or behave like the other boys. He often spent his free time alone in a secluded part of the play area watching the beetles or practicing gymnastics on a tree. He drew curious diagrams and sometimes brought along homemade mechanical contraptions, but none of his fellows could make heads or tails of them. His mind whirring with impressions, questions, and partially formed ideas; he was like a steam locomotive racing away on its own while everyone else was on another track. He couldn't bring himself to join in the rote-based drudgery of the classroom and was tongue-tied when asked to perform simple oral tasks. A fish out of water, he acquired the nickname “Dafty.”

  Life may have been dull at school, but there was plenty of stimulation in Aunt Isabella's spirited household. James especially enjoyed the company of his elder cousin Jemima, who was a rising artist. One of their games was to make “wheels of life” for parlor entertainment: James made the rotating devices and Jemima drew sets of pictures that appeared to show a tumbling acrobat or a galloping horse when the machines were set spinning. Father and son wrote to one other regularly, and James's letters were full of whimsical banter. James addressed one letter to: Mr. John Clerk Maxwell, Postyknowswhere, Kirkpatrick Durham, Dumfries, and signed it anagrammatically as Jas Alex McMerkwell.

  The rote-based drudgery in class gradually gave way to more interesting work, and young Maxwell began to take interest, rising in his second year from near the bottom of the class to nineteenth and winning the prize for scripture biography. Mathematics lessons began in the third year and “Dafty” astonished everyone by mastering geometry with no apparent effort. Promoted to a desk in the top group, he found himself in more sympathetic company and began to make friends. One of them was the star of the class, Lewis Campbell, and, by a stroke of luck, his family moved next door to Aunt Isabella's. On the walk home, the two boys began to share their thoughts on life, and James's world opened up. Now he had someone of his own age who would listen to his teeming ideas and counter with his own. They remained friends for life, and when Maxwell died, Campbell wrote a moving biography. At school, this friendship led to others, including one with Peter Guthrie Tait, who went on to become one of Scotland's great scientists.

  At the age of fourteen, Maxwell published his first paper. It was on the kinds of curves that can be drawn with a pencil, a few pins and a piece of string. Most people know how to draw an ellipse using two pins and a simple loop of string, but by more complex looping, Maxwell produced whole families of curves. It wasn't unusual for him to produce geometrical propositions—he was doing it all the time—but his well-connected father decided to show this one to his friend Professor James Forbes at Edinburgh University, to see if anything like it had been done before. It turned out that the great French mathematician and philosopher René Descartes had investigated similar curves, but that Maxwell's construction was both simpler and more general. His paper was read out for him to the Royal Society of Edinburgh because he was deemed too young to do it himself. He had entered the scientific world of Edinburgh and met James Forbes, who was to play a big part in guiding his career.

  All facets of young Maxwell's life shone brightly. Never one to bear a grudge, he now enjoyed the lively companionship of his schoolfellows and began to excel in English, history, geography, and French, as well as mathematics. He seemed to remember everything he had read and showed an amazing ability to write verse on any topic in impeccable rhyme and meter. He was less fluent in formal conversation—words came in spates between long pauses, and he was shy with strangers. His replies to questions tended to be indirect and enigmatic, leaving the questioner no wiser. Yet when at ease with friends, he reveled in the banter and would entertain them with a flow of surprising observations and metaphors on whatever was the subject of the moment. In the holidays at Glenlair, he joined in the Happy Valley social life, rode, walked the hills, helped with the harvest, and, in the winter, skated and took a hand at curling.

  During the school term, his father visited Edinburgh whenever he could, and the two would take walks on Arthur's Seat, the rocky hill that overlooks the city, or visit other local attractions. Every new experience fed the boy's probing and retentive mind, and one in particular was eventually to bring a result that changed the world. John took James to an exhibition of “electromagnetic machines.” These were early days, and the machines were devices like the magnetic beam engine, built for demonstration rather than for work, but all were testament to the discoveries of the great Michael Faraday. Young Maxwell had been introduced to the wonder of forces acting in space.

  John Clerk Maxwell's plan was for his son to become a lawyer—a more successful one than he himself had been. This seems odd, given his son's obvious gift for science and his own fascination for technology, but his judgment was not wholly at fault this time. Science, then called natural philosophy, was generally thought to be an excellent hobby for a gentleman but a poor career choice: It was poorly paid and opportunities were sparse because there were few professional posts and the post-holders tended to remain for life, as Faraday did at the Royal Institution. Strange as it seems to us, science was not even thought to be particularly useful, as most of the great advances in industry and transport had been introduced and developed not by natural philosophers but by practical men with little theoretical knowledge, like Abraham Darby, the inventor of coke smelting, and George Stephenson, known as “the Father of railways.” James himself had given little thought to the matter. He was drawn to science, but it was far from his only interest—literature and philosophy were stimulating, and perhaps the law would be just as compelling when he got to know it. He had learned enough to know how much more there was to learn, and he was keen to spread his wings. Edinburgh University was a fine place to start, and at the age of sixteen he enrolled there to complete his general education before studying for the law. By way of celebration, he wrote an ironic tribute to his old school in the form of a song—one that we might place somewhere between Robert Burns and Tom Lehrer. The first and last verses ran:

  If ony hear has got an ear

  He'd better tak a haud o’ me

  Or I'll begin, wi’ roarin’ din,

  To cheer our old Academy

  Let scholars all, both grit and small

  Of learning mourn the sad demise;

  That's as they think, but we will drink

  Good luck to Scots Academies.4

  The three years Maxwell spent at Edinburgh University are sometimes described as a fallow period when not much happened. In fact, they did much to make him the kind of scientist he was.

  Scottish universities, Edinburgh in particular, had been inspired by the Enlightenment of the 1700s and early 1800s. They provided a broad education and strove to produce confident, well-rounded young men who could hold their own in any company. Philosophy held pride of place among the faculties: Edinburgh, home of the great David Hume, had two professorial posts, both occupied by famous men. John Wilson, celebrated under his pen name Christopher North, was professor of moral philosophy, and Sir William Hamilton, not to be confused with the Irish mathematician of the same name, was professor of mental philosophy. There was also the chair of natural philosophy, which we would now call science. This was held by James Forbes, who had been instrumental in getting fourteen-year-old Maxwell's paper on oval curves published by the Royal Society of Edinburgh.

  Maxwell chose to study moral philosophy under Wilson, logic and metaphysics under Hamilton, science under Forbes, mathematics under Philip Kelland, and chemistry under Professor Gregory. There were some disappointments, the greatest being Wilson's lectures on moral philosophy, which, to Maxwell, only served to demonstrate that woolly thinking leads to wrong conclusions. Kelland's course on mathematics was, at first, too elementary to be interesting, though thi
ngs improved later, and Gregory's lectures on chemistry suffered by being purely theoretical—laboratory experiments were supervised separately by his assistant, known as “Kemp the practical,” who used quite different methods from those described by Gregory in the classroom. But even negative experiences were put to use: this one helped to form Maxwell's conviction that practical work must be an integral part of any science course, not a tacked-on extra.

  The disappointments were offset elsewhere: Hamilton and Forbes were inspirational. William Hamilton's style was to instill in his pupils a spirit of relentless questioning and criticism. He had been instrumental in introducing the work of Immanuel Kant into Britain, and he used to stress Kant's proposition that nothing can be known about any object except by its relation to other objects. David Hume's notion of skepticism also played a large part in Hamilton's teaching: nothing can be proved, except in mathematics, and much of what we take to be fact is merely conjecture. Deep waters, but to Maxwell they were new and exciting, especially when Hamilton responded to his awkward questions by posing still-deeper questions.

  Maxwell's study of philosophy served him well. One of the exercises he wrote for Hamilton gives us a glimpse of his ability to explore regions of scientific thought beyond the range of his fellow scientists.

  Now the only thing which can be directly perceived by the senses is Force, to which may be reduced light, heat, electricity, sound, and all the other things that may be perceived by the senses.

  He had seen the truth of Kant's argument that the way we detect a solid object is by the force that resists our attempts to move through it. Twenty years later, when checking a draft of William Thomson and Peter Guthrie Tait's Treatise on Natural Philosophy, he had to put them right on this very point. They had defined mass wrongly and had to be told that “matter is never perceived by the senses.”