Faraday, Maxwell, and the Electromagnetic Field Read online

  The Faradays settled in a poor area called Newington Butts, about a mile to the south of London Bridge. Two children, Elizabeth and Robert, soon arrived, and a third, Michael, was born in 1791. James may have picked up some farrier work from a nearby coaching inn called the Elephant and Castle (which now gives its name to the whole neighborhood), but business was slack, his hopes of prosperity came to nothing, and, to make things worse, his health began to fail. The dread of being committed to a debtors’ prison or, worse still, to the workhouse must have been ever present. At times he had to accept charity, probably from fellow Sandemanians, to keep his family from starvation. But he did so with no bitterness or envy of those more fortunate. The children grew up in a lively and loving household, though a crowded one—Michael was soon followed by a young sister, called Margaret after their mother. The family moved again, first to Gilbert Street and then to rooms over a stable near Manchester Square, just off the newly named Oxford Street. Now home to fashionable department stores, this road had other associations in Faraday's time: it was formerly Tyburn Street, along which condemned men made their last journey to the gallows from Newgate Prison.

  After a rudimentary education, thirteen-year-old Michael Faraday began work as an errand boy for George Ribeau, who ran a book and newspaper shop on nearby Blandford Street. He became a familiar figure in the neighborhood—a lively boy with “a load of brown curls and a packet of newspapers under his arm.”2 Ribeau was a French émigré with progressive views who took a warm interest in his young charges. He thought he had found a gem in Faraday and soon took him on as an apprentice bookbinder—a seven-year contract in those days. As far as we know, none of Ribeau's apprentices actually became a bookbinder, but his liberal regime allowed them the freedom to develop their talents in other directions: one became a comedian and another a professional singer.

  Binding books hour after hour, day after day, was tedious work, but it required immense care and skillful hands—qualities that were to serve Faraday well later in life. What opened up the world for him, though, were the books themselves: picture books, adventure stories, novels, books on philosophy, and, most of all, anything about the physical world and men's attempts to find out how it worked. He became a seeker of truth. As he later recalled: “I was a very lively, imaginative person. I could believe in the Arabian Nights as easily as in the Encyclopaedia. But facts were important to me and saved me. I could trust a fact but always cross-examined an assertion.”3

  The more he read on any topic, the more he became aware of his own lack of education. Then, just when he needed it, he found a book that could have been written for him alone, The Improvement of the Mind, by the Reverend Isaac Watts. Faraday threw himself with all the vigor of youth into Watts's program for self-improvement. He tried to learn correct speech and told friends to put him right every time he made a grammatical slip in conversation. He took every opportunity to widen his knowledge and began to keep a “commonplace book,” setting down facts, especially scientific ones, for future reference. Even in these simple notes he strove to follow Watts's advice always to use precise language and be guided by observed fact. And he took to heart another of Watts's instructions: one should “be not too hasty to erect general theories from a few particular observations, appearances or experiments.”4 One can see here the seeds of the scientific method Faraday later made his own: take imagination to its limits but draw no conclusions without solid experimental proof.

  Yet another of Watts's suggestions was to supplement reading with the “living discourse of a wise, learned and well-qualified teacher,”5 so Faraday borrowed a shilling from his brother and went to a lecture on electricity by John Tatum, a silversmith who had founded the City Philosophical Society. This was a kind of common man's Royal Society, which held weekly meetings attended by a motley collection of self-improvers, all eager to hear of the latest scientific discoveries. Faraday soon joined the City Philosophical Society and became its most diligent student; at every lecture he took rough notes that he copied out in a fair hand at home. He enjoyed the boisterous company of his fellow students, several of whom became lifelong friends. The closest was Benjamin Abbott, a Quaker with a job in a mercantile house. He became Faraday's soul mate, someone who could help him acquire the social poise and the speaking and writing skills he lacked, and to whom he could pour out his innermost thoughts. Faraday loved music and later, when he could afford it, became a keen operagoer. As with all his interests, he had to try things for himself—he took up the flute and enjoyed taking the bass part in choral singing.

  He also made his own experiments, for example, he would use glass jars lined with metal foil to store static electricity, with which he could charge up household objects and administer mild shocks to himself and anyone else who wanted to join in. He was already beginning to think about how electricity worked and questioned the truth of an ostensibly authoritative article in the Encyclopaedia Britannica. Its author, James Tytler, had confidently propounded Benjamin Franklin's “one-fluid” theory, which ascribed positive charges to an excess of a mysterious electrical fluid and negative ones to a dearth. Most British scientists favored this theory, but Faraday's early preference was for the French “two-fluid” theory, in which one type of fluid gave rise to positive charges and the other to negative. Even there, he thought there was something amiss with the standard interpretation. The young upstart was right to doubt his elders and betters, but the problem turned out to be more difficult than anyone had imagined. It was many years before Faraday came close to explaining static electricity to his own satisfaction, and it was half a century before his own follower, Maxwell, put the last piece in the puzzle.

  Just as Faraday thought he was beginning to come to grips with electricity, his plans for further work were knocked sideways by an astonishing discovery made in Italy. John Tatum had learned of the voltaic cell, or battery, invented ten years earlier by Alessandro Volta, and he described it to his audience at a City Philosophical Society meeting. Familiar devices for storing electricity, like the foil-lined glass jars Faraday had used, released all their charge in one burst, but the battery produced something hitherto undreamed of—a continuous flow of electricity. What was more, the new electric currents could be used in simple experiments to investigate the structure of matter. A vast new region of science was opening up. And it was easy to make a battery: in 1800, Volta had provided detailed instructions. Make a stack of metal plates, alternately copper and zinc, interleaved with layers of pasteboard dampened with salt water, and, amazingly, an electric force will be generated through the stack—the more plates, the greater the force. Connect the two end plates with a metal wire, and a continuous current flows. This was not all. Experimenters had found that if they fixed a wire to each end plate and dipped the two wire ends in a solution of a chemical compound, the electric force would cause the constituent parts of the compound to separate, with one part gathering at one wire's end and one at the other.

  Simply hearing or reading of such things was never enough for Faraday. When assessing the work of others, he always had to repeat, and perhaps extend, their experiments. It became a lifelong habit—his way of establishing ownership over an idea. Just as he did countless times later in other settings, he set out to demonstrate this new phenomenon to his own satisfaction. When he had saved enough money to buy the materials, he made a battery from seven copper halfpennies and seven discs cut from a sheet of zinc, interleaved with pieces of paper soaked in salt water. He fixed a copper wire to each end plate, dipped the other ends of the wires in a solution of Epsom salts (magnesium sulfate), and watched.

  Both wires became covered in a very short time with bubbles of some gas, and a continued stream of very minute bubbles, appearing like small particles, ran through the solution from the negative wire. My proof that the sulphate was decomposed was, that in about two hours the clear solution became turpid: magnesia [magnesium oxide] was suspended in it.6

  If there was one moment that confirmed the cours
e of Faraday's working life, this was surely it. Nothing less than a career in science would do. He had already found the perfect instructor: Jane Marcet, who spoke to him through her remarkable book Conversations on Chemistry. Originally published anonymously in 1805, it became hugely popular, especially in America, where pirated versions abounded. In a manner reminiscent of Galileo in his Dialogue on the Two Chief World Systems, the author's alter ego, Mrs. B., instills in her pupils, diligent Emily and flighty Caroline, a scientist's curiosity about the physical world and a delight in discovering a little about it. They do experiments, using materials from around the house, and learn about heat and light, all the while being careful to draw conclusions only from observed fact. All this chimed precisely with Watts's guidance on life in general, so even before Faraday's experimental career started in earnest he had the procedure clear in his mind: explore; observe; experiment; eliminate sources of error; compare theory with experimental findings; keep thinking; and finally, draw whatever conclusions stand the test but even then be open to challenge—don't become a prisoner of your own ideas.

  The daughter of a rich London merchant, Jane Marcet had married Alexander, a Swiss-born physician, and had come to share his passion for science. They took a well-informed interest in the latest developments, and their social circle included many of the leading scientists. One can picture their elegant dinners, at which prominent fellows of the Royal Society might gather to discuss Thomas Young's wave theory of light or Johann Ritter's discovery of ultraviolet radiation. This world was far removed from Faraday's. The rules of society were well described in the hymn “All Things Bright and Beautiful,” written a few years later by Fanny Alexander. One verse runs:

  The rich man in his castle,

  The poor man at his gate,

  God made them high and lowly,

  And ordered their estate.

  Blacksmiths’ sons and bookbinders’ apprentices did not, indeed should not, aspire to friendship and fellowship with people of higher rank. But science transcends class distinctions, and Jane Marcet had mentioned in the preface to her Conversations the two factors that were to transform Faraday's life—the Royal Institution and Humphry Davy.

  Compared with the venerable Royal Society, the Royal Institution was an upstart establishment. Some of its fifty-eight founders were already prominent fellows of the Royal Society, and they intended the new Institution to complement rather than rival its older sibling. Its purpose, formally agreed to at the inaugural meeting on March 7, 1799, was to further “the Application of Science to the Common Purposes of Life” by means of “courses of Philosophical Lectures and Experiments.” It was financed initially by subscription, and the prime mover among the founders was one of the most extraordinary characters in the history of science—an anglicized American named Benjamin Thompson who bore the title Count Rumford. Thompson had overlapping careers as fortune hunter, rake, philanderer, spy, military governor, inventor, park designer, scientist, and social reformer, and he can be described fairly as outstanding in all these roles. His title of count (of the Holy Roman Empire) had been bestowed by a grateful elector of Bavaria for transforming the Bavarian army from a rabble into a fit and efficient fighting force—he chose the Rumford part of the title from the town in New Hampshire where, in a part of his life little known to his British colleagues, he had abandoned his wife and daughter two decades earlier. Thanks in the main to Thompson's vision and drive, the Institution gained its Royal Seal in 1800 and set up business at 21 Albemarle Street in London, an address it still occupies today. Ever unpredictable, Thompson decamped to Paris after nearly ruining the fledgling organization with his over-ambitious plans for educational courses, but before going he saved the situation by a masterstroke that would make the Institution famous and fill its coffers. He recruited Humphry Davy, a cocksure twenty-three-year-old from the West Country with a marked Cornish accent, to run the chemical laboratory and act as assistant lecturer.

  Davy, debonair and strikingly handsome, had already acquired notoriety from some widely reported exploits with mind-altering nitrous oxide, laughing gas, so the people from London's fashionable elite who bought expensive tickets for his early lectures were probably drawn as much by the hint of scandal as by scientific interest. They were not disappointed—Davy amply satisfied their wish for excitement. But there was more: he enlightened and inspired them at the same time by presenting the wonders of science with romantic eloquence, passion, and pyrotechnical demonstrations. Word spread, and even bigger crowds came to the next course of lectures. Albemarle Street had to be made London's first one-way thoroughfare to prevent it from being blocked by carriages. When he was ill in 1807, there were so many inquiries about his health that the Royal Institution posted hourly notices outside its headquarters. Nothing like Davy's popularity had been seen before. Half his audience were women—many of them young, enraptured by the dashing young man. One wrote “those eyes were made for something besides poring over crucibles.”7

  Davy was not only a showman. His groundbreaking work in the Royal Institution laboratory put him in the front rank of scientists. He discovered the elements potassium and sodium by sending an electric current through molten compounds in order to separate their components. The method was the same in principle as that by which Faraday managed to decompose Epsom salts in Ribeau's workshop, but rather larger in scale: Faraday's battery, made from halfpennies and home-cut zinc discs, had seven voltaic cells while Davy's had two thousand. At the end of another series of experiments, Davy concluded that chlorine, the green gas given off when hydrochloric acid (then called muriatic acid) reacted with manganese dioxide (then called pyrolusite) did not contain oxygen, as was generally believed, but was an element in its own right. This was close to heresy according to followers of the great French chemist Antoine Laurent Lavoisier, who had assured everyone that oxygen was a necessary element in all acids, and it was some years before Davy's correct view prevailed.

  Neither Faraday nor his friends at the City Philosophical Society could afford tickets to the lectures, but they read and heard of the great man's achievements. The knowledge that Davy was making scientific history only a few streets away was both thrilling and frustrating. Faraday felt the buzz, but it was like hearing the sounds of a party going on behind closed doors. Then one day, to his joy, he was given a ticket to a course of four lectures by Davy. It was his unfailing diligence at Society meetings that had brought this unexpected dividend. His carefully written and illustrated notes of the lectures were so beautifully done that Ribeau used to show them off to customers at the shop. One of them, Mr. Dance, who happened to be a member of the Royal Institution, was impressed beyond words by Faraday's work and straightaway presented him with the ticket.

  Faraday arrived early for each lecture to be sure of getting the best seat in the gallery and sat with rapt attention as Davy put on a tremendous show, not only demonstrating his groundbreaking experiments but also conveying to the audience the joy of it all. As was his habit, Faraday took thorough notes of all that went on and wrote them up, with his careful penmanship, at home. Wonderful though Davy's demonstrations had been, Faraday felt the need to repeat the experiments and see the results himself. For him, this was the only way to understand what was really going on in the physical world. He did what he could, using makeshift equipment gathered from home or the shop, and dreamed that one day he might have a laboratory of his own.

  With the end of his apprenticeship approaching, Faraday wrote to Sir Joseph Banks, president of the Royal Society, asking for a scientific post, no matter how menial, but had no reply. Checking with the porter at the Society's headquarters in Carlton Terrace, he discovered that Banks, or perhaps his secretary, had annotated his letter with the comment “No answer required.”8

  The apprenticeship over, he took a job as a bookbinder with Henri de la Roche, another French émigré. Work took all the hours of the day, and the outlook was bleak indeed. But Sandemanians didn't sulk, they just got on with the job; de
la Roche was so impressed with Faraday that after only a few months, he offered to make him heir to the business. This was not what Faraday wanted. In despondency, he wrote to a friend:

  As long as I stop in my present situation (I see no chance of getting out of it just yet), I must resign philosophy entirely to those who are more fortunate in the possession of time and means.9

  Just when things looked blackest, he had a request for help from, of all people, Humphry Davy.

  Faraday's white knight, Mr. Dance, had come to his aid again. When Davy was temporarily blinded by an explosion in the laboratory and needed an assistant, Dance had said he knew just the man for the job. Faraday took leave from work and spent a few euphoric days in his hero's presence. It was soon over, and the vanished glimpse of a brighter world made the work routine more mind-numbing than ever. Nothing ventured, nothing gained: he carefully bound his notes of the lectures and sent them to Davy, asking if there was any chance of a permanent position at the Royal Institution. A few days later, on Christmas Eve 1812, he was overjoyed to get a reply.

  Sir,

  I am far from displeased with the proof you have given me of your confidence, and which displays great zeal, power of memory, and attention. I am obliged to go out of town till the end of January: I will then see you at any time you wish.

  It would gratify me to be of service to you. I wish it may be in my power,

  I am, Sir,

  Your obedient humble servant,

  H. Davy

  Faraday kept the letter all his life, but it didn't bring an immediate reward. At the interview, Davy said that he would like to employ Faraday, but all the posts at the Institution were filled and none was likely to become vacant soon. Despondency returned, but not for long. One evening, a carriage pulled up outside the Faradays’ house and a footman delivered a message. Would Mr. Faraday kindly visit Mr. Davy in the morning?