The Spinning Magnet

by Alanna Mitchell

  It was Ørsted’s seminal paper, sent to Davy by stagecoach in 1820, that enticed Faraday into the world of electromagnetics, James explained. By then Faraday’s genius had propelled him away from being a mere laboratory assistant and into doing his own experiments at the Royal Institution. Ørsted’s paper had induced many others to write about electromagnetism and by 1821, everyone was confused. Faraday’s friend Richard Phillips, editor of the journal Annals of Philosophy, commissioned Faraday to write the definitive review paper explaining to a hungry scientific community what this electromagnetic phenomenon really was.

  So Faraday read everything he could find. It was a hodgepodge of contradictory information. He found Ørsted’s talk of electrical conflicts simply confusing. He dived into Ampère’s mathematical descriptions of electromagnetism, but he had never been trained in advanced math and once described equations as “hieroglyphics.” Ever the hands-on experimenter, he decided to repeat all the experiments described in the other journal articles, including those of Ørsted. Eventually he wrote up his findings into a series of articles for Phillips, signing his name for public consumption humbly, and mysteriously, as “M.” Here was the first understandable explanation of electromagnetism that the world had seen. The articles were so popular that the public implored their author to unmask himself. Faraday did so and tasted fame.

  But as Faraday repeated the experiments of others, he had thought up some of his own. What caught his attention was precisely what had made Ørsted’s compass needle move when it was near the current of electricity. The traditional thinking, which Ampère supported, was that the needle and the wire were being attracted and repelled by each other, that the power between them leapt across empty space and distance. Faraday began to wonder whether there was instead a circle of force in the space around the wire—a physical thing—that was affecting the compass needle. That could be one way to explain the peculiar circular effect Ørsted had observed.

  Being Faraday, he devised an elegant experiment to test the theory. On September 3, 1821, he took a basin, a glob of wax, an iron magnet, and a quantity of quicksilver, or mercury, which is a conductor of electricity. He fixed the magnet, north end up, to the bottom of the basin with the wax and then filled the basin partway with mercury. Then he hung a piece of wire from an insulated stand so it could swing freely in the mercury around the magnet. Finally, he created a closed electrical loop by connecting a battery to the wire on one end and the mercury on the other. The wire moved clockwise around the magnet. The electrical current running through the wire created a magnetic field. That magnetic field interacted with the field surrounding the magnet, causing the wire to rotate around the fixed magnet. Then he reversed things. He loosed the magnet and fixed the wire. The magnet could float in the mercury, attached by a tether to the bottom. The wire was immobilized in the center of the basin of mercury. The magnet revolved around the wire as soon as Faraday made the current run.

  This was the first electrical motor: the creation of mechanical energy from the power produced by an electrical current and a magnet. Faraday called it an electric magnetic rotation apparatus. He seems to have had no precise concept of what such a machine might be made to do—he could not have foreseen the mechanization of the world that we now experience—but he knew it was important. For one thing, it reinforced his odd idea that magnetic forces might curve around the magnet, filling space. His summation, entered into his laboratory notebooks describing the experiments, reads: “Very satisfactory, but make a more sensible apparatus.”

  It would be a decade before he had the time to turn his attention back to the puzzle of electromagnetism.

  CHAPTER 15

  magnets making currents

  Sipping a latte in the building that is renowned because of the work Faraday did within its walls, it’s hard for me to take in just how much of an outsider he was when he began his career. Today, Faraday permeates the place. The elegant instruments he made by hand, the controlled-access archive of his notebooks, and the enduring lore of his story are mainly what draw people here. A statue of him stands rather grandly at the base of the building’s curved staircase, his austere form draped in academic gowns, grasping a replica of the ring coil, his most famous apparatus. A bust of Faraday by the nineteenth-century sculptor Matthew Noble is in another part of the building. Margaret Thatcher so idolized Faraday—he was born working class, like her, and studied chemistry, like her, and made good, like her—that she borrowed the bust in 1982 after she became Britain’s prime minister and made it the first thing visitors saw when they entered 10 Downing Street, the official residence. One hundred and seventy years after he set foot in the Royal Institution on charity tickets, Faraday had been pressed into service as the prime symbol of British can-do.

  The change in his status was remarkable. It wasn’t only that Faraday had been born into trade rather than marked for a scholarly life. It was also his religion. Like his journeyman blacksmith father, Faraday was a Sandemanian. It was a straightlaced Protestant sect, born by way of dour Scottish Presbyterianism. Its adherents met each Sunday to ritually wash one another’s feet and feast together in memory of Christ’s life and sacrifice. They preferred one another’s company, cautious about too much socializing with others and often marrying within the faith. Ever mindful that the ultimate reward was a place in the kingdom of heaven, they eschewed the riches of the world, preferring plain living and the practice of sharing what they had with the poor. They knew that they could count on salvation, and it fostered serenity, even joy. “A peculiar aura of good nature” surrounded the Sandemanian group, wrote Williams, Faraday’s biographer.

  In Faraday’s time, not being Anglican, the official Protestant denomination of England, was a severe handicap, James explained, episodically wiping coffee from his full, walrus-style mustache. Professors at the Universities of Oxford and Cambridge, the most prestigious higher-education institutions in Britain, had to be Anglican by definition. Naval and military officers, some of whom were also natural philosophers, were also required to be Anglican, apart from a few exceptions for Catholic Ireland. Not only that, but being a scientist in itself was somewhat countercultural. By James’s calculation, only about a hundred people in Britain were paid to do science in 1812, the year Faraday went to the Royal Institution to hear Davy’s lectures. Many who devoted their lives to it were independently wealthy members of the landed and titled classes. Some, like Davy, wanted to join that elevated echelon. Not Faraday. Twice Faraday was offered the esteemed position of head of the Royal Society and twice he declined. His concession to glory was to accept a “grace and favour” home outside London late in life from Queen Victoria’s consort, Prince Albert, where he lived at the Crown’s expense in his final years.

  Yet while Faraday’s religious faith made him an outsider, it was also one of the reasons he succeeded. He saw things differently from others. And he had a different reason to pursue his experiments. Faraday did science in order to understand the world he believed God had created. In turn, his belief in God informed his understanding of science. It was a slightly different philosophy from that of Ørsted, who believed in an almost pantheistic philosophy, that every facet of nature showcased God’s greatness. Instead, Faraday perceived the presence of intricate, shadowy, and even tricky godly laws that were responsible for everything around him. Discovering them would take ingenuity, and a lifetime.

  That same religious faith prevented Faraday from believing in atoms. That idea ran against his understanding of how God had created the world. What today we see as a combination of atoms, or a molecule, Faraday saw as a solid piece of material that could be divided into yet smaller pieces of itself. He had no concept of the airy interior of an atom surrounded by electrons that Bohr came up with in the following century. For similar reasons, he loathed the term “scientist,” James told me. It comes from the Latin scientia, which means “knowledge,” and Faraday believed the term stripped God out of why the world was
there in the first place. Faraday preferred to be called a “natural philosopher” or a “man of science,” James said.

  People were never quite sure how to react to Faraday, James told me, getting up from the café table to show me to the museum in the basement. They didn’t know where his ideas came from. Perhaps because he had such an atypical background, he had the knack of being able to envision how natural forces might interact with an apparatus and then think up experiments to test those visions, regardless of what traditional scientific theory dictated. All of it set him apart. But he was correct so often, James said, that they couldn’t dismiss him.

  At the entryway to the museum was a display containing the home-made piece of equipment that Faraday is most famous for, adorned with pumpkin-colored explanatory signs. Dated August 1831, it was Faraday’s most inspired attempt until then to make electricity from magnetism. Faraday had spent most of the 1820s mired in a project Davy had pressed on him, unable to work on other experiments. Davy was chairman of the Board of Longitude and, despite Harrison’s H4 clock of 1759 that had technically resolved the longitude problem, the British Admiralty was still trying to figure out a cheap and easy way for sailors to figure out where they were. The board had placed its money on reading the heavens, and Davy had decided that Faraday could do the important job of making better optical glass for sailors’ telescopes. It was miserable work. He had to have a glass furnace installed in his laboratory. Later in life, Faraday spent a great deal of time trying to prove that secular variation of the magnetic field was linked to fluxes of oxygen in the atmosphere as it warmed and cooled over the course of days and seasons. (He was wrong.) But at that time, he was not much interested in terrestrial magnetism or longitude. He abandoned the project as soon as he decently could after Davy died in 1829, and resumed the electromagnetic experiments that were to consume the following decade of his life.

  Again, Ørsted’s pioneering ideas were an influence. During his European trip of 1801, Ørsted had seen some of the astonishing images created by the German physicist and musician Ernst Chladni. Chladni had run a violin bow across the edge of a metal or glass plate on which he had scattered sand. The waves from the vibrations made geometrical patterns. It was like being able to see sound. By 1806, Ørsted had begun to think about whether sound and electricity might make similar patterns and did his own experiments using fine moss seeds on plates. Faraday read about his work, and in early 1831, added light into the mix. Could all three—sound, electricity, and light—be made up of vibrations? He set up a six-month series of acoustic experiments to test the idea. His astonishing conclusion was that the sound vibrations existed in the air. It put paid to the idea that the air was empty. From there, it was a short step for Faraday to begin thinking about electricity as waves. By late summer, he started experimenting.

  • • •

  At that point in the history of electromagnetism, anyone could make a magnet from electricity. All it took was placing a piece of iron inside a coil that thrummed with electrical current and the iron became a magnet that held its charge. Faraday wanted to do the reverse: make electricity from a magnet. As a first step, he commissioned a wrought-iron ring, seven-eighths of an inch thick and six inches from outer edge to outer edge. In his mind’s eye, he divided it in half. Around one half, he wound three twenty-four-foot-long pieces of copper wire—the same type then used in making bonnets—as tightly together as he could. The more turns the wire took, the greater the magnetic effect of the electric current would be. He insulated each turn of coil from the next with string, as insulated wire was not available in 1831. He kept going, making another layer of wire coils on top of the first, insulating each layer with cotton calico dress cloth. Then he performed the same process on the other half of the ring, leaving spaces on the ring between the two coiled sides. James told me that he has estimated it would have taken about ten days to make the apparatus.

  Today, you can see from the display that the calico is discolored and a bit tatty. Pieces of the string have sprung loose. But the experiment Faraday conducted with this rather homely device is one key to the vast electrical infrastructure that carries electrical currents around the world. It was the first transformer, capable of making fast-moving electrons pushing hard at high voltages slow down enough to be useful in everyday, low-voltage applications. Today, transformers in power stations allow the whoosh of electricity generated by water, sun, wind, nuclear reaction, and coal to flow at lower speeds into your lamps and computers and other devices run by electricity.

  On the day he did his experiment, Faraday hooked up one side of the wire-coiled iron ring to a battery with a switch. He hooked up the second side to a galvanometer, a device to measure electrical current. He flipped the switch. Electrical current from the battery flowed through the copper wire on one side of the ring, producing a magnetic field. The wire on the other side of the ring briefly made the galvanometer flick with a small pulse of current. Then it went back to its neutral position despite the strong current that continued to flow on the other side. When Faraday switched the battery off, the other side again showed a small, brief burst of electricity, but in the opposite direction on the galvanometer. Faraday’s conclusion was that electricity was created not when the magnetic flow began but when it changed. The electricity created on that other side was also lower-voltage than the original battery current, the basis of the device’s usefulness as a transformer. The device has gone down in history being called an induction ring, meaning that it had induced an electrical current, however intermittent.

  But why did a change in magnetic flow make electricity? And could electricity be made using a magnet alone, without the current from a battery? Three months later, Faraday found some answers. It was a simple experiment, the same one Andrew D. Jackson replicated for me in his office at the Niels Bohr Institute in Copenhagen. Faraday took a hollow iron tube and wound its outside with copper wire insulated with cotton. Then he hooked the tube up to a galvanometer and slid the magnet through the tube. The galvanometer recorded a current. When he slid it the opposite way, the galvanometer recorded a current in the opposite direction. Just a twitch. As the magnet moved it created an electrical current, pushing electrons in the wire surrounding the tube. That electric current in turn created its own magnetic field. Faraday had created a generator of electricity without using a separate source of electricity.

  James and I had arrived in a hallway in the basement. He stopped at a display of the pile Volta gave to Faraday in Milan in June 1814, when Volta was nearly seventy. It is one of the institution’s treasures. Among the earliest batteries ever made, it looks unassuming, standing perhaps a foot high on a highly polished wooden base. Davy wanted the pile to be bigger and stronger and more physically stable, so he came up with the innovation of turning it on its side, James said, chuckling. That led to the troughs Ørsted used in his grand experiment of 1820.

  Farther along, past the painting of James in period costume, was Faraday’s magnetic laboratory, arranged to show what it had looked like in the 1850s toward the end of his working life. The laboratory was preserved, not because Faraday was such a legend in his own time but by accident. After he died in 1867, nobody bothered to clear out the materials inside. But by 1931, the hundred-year anniversary of Faraday’s discovery of the transformer and generator, he had become a symbol of the British role in creating modern technology. People began unpacking his old laboratory, now a basement storeroom, and found his instruments, chemicals, vials, even the dumbwaiter where servants had long ago loaded things to be carted to higher floors. Faraday used the dumbwaiter to store experiments and its doors still bore the red wax seals he had placed there to signify that he had experiments locked inside.

  Faraday’s experiments and findings in magnetism and electricity ranged much further after these early successes. One of his contributions was to establish unequivocally that all forms of electricity were identical, no matter how they were produced, James explaine
d. At that time, scientists thought of electricity as coming from five different sources: static (known as “common”), voltaic, animal, lightning, and thermal. Did each type produce the same results in experiments? Faraday painstakingly went through what was known about the qualities, or “identity,” of each and ran experiments to test each type, filling in a chart as he proceeded until he proved they were the same thing.

  Each test reinforced his idea that lines of force filled the air. It’s the same idea grade school students see during the experiment with iron filings arranging themselves in lines across a paper overtop a bar magnet. On April 3, 1846, Faraday introduced the idea in an extemporaneous public talk, one of his famous “Friday evening discourses” at the Royal Institution. He had arranged for another speaker to give the lecture, but that person had bolted due to nerves. Faraday hurriedly took the stage in his place but found himself with twenty minutes to spare once he had finished his topic. So, for the first time in his life, he went off book. In retrospect, it was an extraordinary moment in science. Faraday summoned up a vision of the world filled with lines of electric and magnetic force, and perhaps even other forces such as gravity. They had physicality. They formed matter. He was describing the electromagnetic field, other fields, and some of the concepts that would eventually underpin quantum field theory. But while he could describe what he had found in precise, sometimes bespoke, language, he lacked the ability to describe his findings in the universal language of physics: mathematics.