Faraday, Maxwell, and the Electromagnetic Field Read online

  I hope to discover a method of forming a mechanical conception of this electro-tonic state adapted to general reasoning.

  In part 2 he did, indeed, find a way to describe the electrotonic state mathematically. We can imagine Faraday's joy. Here, at last, was somebody prepared to take on his ideas and work with them. He replied:

  I received your paper, and thank you very much for it. I do not venture to thank you for what you have said about “Lines of Force” because I know you have done it for the interests of philosophical truth; but you must suppose it is work grateful to me, and gives me much encouragement to think on. I was at first almost frightened when I saw the mathematical force made to bear on the subject, and then wondered to see that the subject stood it so well.23

  Perhaps emboldened by Maxwell's support, Faraday published a paper formally proposing gravitational lines of force, extending an idea first mentioned in his “Ray-vibrations” talk. He knew that the reaction of the great body of his fellow scientists would be disbelief, and he may have felt some anxiety when he asked Maxwell for an opinion. He needn't have worried. Maxwell sent a long and thoughtful reply, concluding that the idea was sound and that the gravitational lines of force could “weave a web across the sky” and “guide the stars in their courses.”24 To this, Faraday responded:

  Your letter is the first intercommunication on the subject with one of your mode and habit of thinking. It will do me much good, and I shall read and meditate it again and again…. I hang on to your words because they are to me weighty and give me great comfort.25

  Faraday had found his successor.

  Faraday's achievements during his last decade are not of the kind that make the history books. They are nevertheless remarkable, accomplished against the background of both ever-diminishing powers of memory and spells of nervous exhaustion that eventually made even the simplest mental task wearisome.

  Much of the work was inspired by a strong sense of public duty, nowhere better shown than by his service to Trinity House. He had given up trade and a profitable career as a consulting chemist to pursue the life of a natural philosopher, whose thoughts were elevated to the highest peaks of abstraction, far removed from the mundane daily routine. In his later years, with his unruly white hair, he even looked the part of the unworldly, absentminded professor. Yet, with his work for Trinity House, he became a practical-minded Victorian businessman, alert to budgetary matters and hard on anyone who proposed unnecessary or wasteful innovations to lighthouse operations.

  During the late 1850s, he wrote more than twenty reports for Trinity House. They covered all aspects of lighthouse operation, but the main concerns were the brightness and reliability of the lights, and one of Faraday's tasks was to oversee the experimental introduction of electric light as an alternative to oil or gas-fueled lamps. After many preliminary tests, a full operational system, though still an experimental one, was installed at South Foreland, near Dover, in 1858. A magneto-electric generator driven by a steam engine supplied current to a carbon-arc lamp, and the first electric light shone across the English Channel. Several similar electric systems followed at other lighthouses, but their high cost and less-than-perfect reliability caused the electrification program to be put off until the 1920s, when filament light bulbs and central generation of electricity at last made it a practical proposition.

  Faraday made frequent inspection visits to lighthouses and went out in all kinds of weather on the Trinity House vessel to test the visibility of the lights from the sea. Such work would have tested the mettle of a man half his age, as is evident from a report he made in 1861 of a routine visit to South Foreland. He was seventy years old.

  I went to Dover last Monday; was caught up in a snowstorm…could not go to the lighthouse that night; and finding next day that the roads on the downs were snowed up returned to London. On Friday I again went to Dover…hoping to find the roads clear of snow; they were still blocked up towards the lighthouse, but by climbing over hedges, walls and fields, I succeeded in getting there and making the necessary enquiries and observations.1

  It is difficult for us today to appreciate the immense importance then attached to saving lives (and cargoes) at sea. As late as 1912, the Nobel Prize in physics went to Niels Gustav Dalen for inventing a way of feeding gas automatically to lighthouses and buoys. His achievement, in the committee's judgment, had surpassed those of rival nominees Albert Einstein, Max Planck, Hendrik Antoon Lorentz, Ernst Mach, and Oliver Heaviside. Faraday's lighthouse work was a service to his fellow men, wholeheartedly given and well appreciated. And, rather appropriately, one of Faraday's comments on lighthouses illuminates for us how religious faith inspired his whole approach to scientific work. In a report, he wrote:

  There is no human arrangement that requires more regularity and certainty of operation than a lighthouse. It is trusted by the Mariner as if it were a law of nature, and as the Sun sets so he expects that, with the same certainty, the lights will appear.2

  In the laboratory he sought to reveal more of God's laws of nature, and in his work for Trinity House he treated these laws as a model to be emulated to the highest degree possible.

  Faraday was the man the government turned to for practical scientific advice on any topic. During the Crimean War, the War Office had consulted him on what would by today's rules have been a highly classified matter. They asked him about the likely formation and movement of clouds of poison gas, a weapon then being considered to help defeat the Russians. In replying, he drew on his memories of Mount Vesuvius from the Grand Tour of half a century earlier, when a treacherously changing wind had blown noxious fumes from the crater in his direction, almost choking him. Evidently, poison gas was a double-edged weapon; the War Office decided not to use it.3 This episode suggests that Faraday could remember events of fifty years ago more clearly than those of last week.

  He advised on how best to preserve paintings in the National Gallery in London and artifacts such as the Elgin Marbles at the British Museum. He also did his best to encourage schools to improve the woeful education in science that most of them provided. He was appalled at the failure of otherwise well-educated people to understand even the simplest scientific principles. On one occasion he complained to the public-school commissioners:

  They come to me and they talk to me about things that belong to natural science; about mesmerism, table turning, flying through the air, about the laws of gravity; they come to me to ask questions, and they insist against me, who think I know a little of these laws, that I am wrong and they are right, in a manner that shows how little the ordinary course of education can teach these minds…. They are ignorant of their ignorance…and I say again there must be something wrong in the system of education which leaves minds, the highest taught, in such a state.4

  The authorities were, indeed, ignorant of their ignorance. Faraday might as well have been talking to the wall: Latin and Greek, with a smattering of Euclid, remained the staple diet in English public-school education for some time.

  To the end he continued to seek scientific truth. Over the years, he became more and more convinced of the unity of all nature's forces and an imperative was to search for evidence that the force of gravity was linked to those of electricity and magnetism. His experiments on gravity were heroic failures. Back in 1849 he had rigged up a helix of copper wire 350 feet long, with its axis vertical, and dropped blocks of various substances through it—from the high ceiling of the Royal Institution's lecture theater to a cushion on the floor. He reasoned that a material body held stationary amid gravitational lines of force might be in a state of strain akin to the electrotonic state of a metal wire amid magnetic lines of force. If so, then perhaps the strain would be relieved when the body was allowed to fall freely, and this might—by analogy with electromagnetic induction—result in a current in the coil, which could be detected with a galvanometer. He tried dropping blocks of iron, copper, bismuth, and other materials. No current, but the results didn't shake his “strong feeling
of the existence of a relation between gravity and electricity,” and in 1859 he returned to the task.5

  This time he tried raising and lowering huge, electrically charged blocks of lead through the longest vertical distance he could find, to see if the charge varied. After considering the tower at the Houses of Parliament, he settled on the 165-foot shot tower6 near Waterloo Bridge for his experiment. There was no significant variation in the charge, but Faraday wrote up the results and submitted them to the Royal Society. On this topic, Faraday thought, even a negative result was important enough to publish. The Society's secretary, George Stokes, did not agree. Like most of his colleagues, he never took Faraday's ideas on the unity of forces seriously, and he believed (correctly) that he was saving the revered old man from ridicule by advising him to withdraw the paper. Faraday acquiesced.

  His very last experiment was performed in March 1862, when he investigated the effect of a magnet on the light spectra of incandescent substances—his mind was still testing the boundaries of what was physically possible. He lit a gas flame between the poles of a magnet and looked for optical effects.

  The colorless Gas flame ascended between the poles of the Magnet and the salts of Sodium, Lithium, etc. were used to give color. A Nicol's polarizer was placed just before the intense magnetic field and an analyzer at the other extreme of the apparatus. Then the E Magnet was made and unmade but not the slightest trace of any effect on or change of the lines in the spectrum was observed in any position of the polarizer or analyzer.7

  Another failure. But, to us, Faraday's genius and vision shine through. Here, as in his quest to unify all known forces, he was sowing a seed for a harvest to be gathered by future scientists. In 1897, the Dutch physicist Peter Zeeman repeated the experiment, using a stronger magnetic field and a more refined apparatus, and he found the very effect that Faraday had been looking for. The Zeeman effect, as it is known today—the splitting of the light spectrum into several components in the presence of a magnetic field—makes possible such techniques as magnetic resonance imaging. We can only wonder at the man who, even with fading mental powers, was able to envisage this effect of magnetism on light.

  As Faraday's health and mental faculties declined, he began to relinquish his various responsibilities at the Royal Institution, finally handing over the directorship to John Tyndall in 1865. The consequent loss of income, and of his flat, would have been a worry, but in 1858 Prince Albert, a great admirer, had asked the queen to put a house at Hampton Court at his disposal. Faraday had refused at first, fearing the high cost of repairs, but the queen said she would pay. He and Sarah moved in, and the new house became his last home.

  He maintained his resolution not to be distracted from his scientific investigations by commercial work or by accepting high office. The Royal Society asked him to accept their presidency in 1857. Faraday declined. His health was not up to it, and the bitter taste from his election to F. R. S. back in 1824 had not entirely faded; when asked for a list of the many scientific honors he had received over the years, he commented:

  One title, namely that of F. R. S. was sought and paid for; all the rest are spontaneous offerings of kindness and goodwill from the bodies named.8

  A rumor once got around that Faraday had been knighted. When somebody wrote asking about it, Faraday replied:

  I am happy that I am not a Sir, and do not intend (if it depends upon me) to become one.9

  There is little doubt that, had he wished, Faraday could have become a knight and probably, later, a baron, as William Thomson did. But he was more receptive to honors from overseas. Following the precedent of Davy's award of the Napoleon Prize,10 he accepted from Napoleon III the title of Commandeur de la Légion d'Honneur. This was by no means the only foreign title he held. He was a Chevalier of the Prussian Order of Merit and, by order of the Royal House of Savoy, a Knight Commander of the Order of St. Maurice and St. Lazarus. One may wonder why plain Michael Faraday, who held to the simple life, scorned pomp, and spurned civic honors in his own country, was happy to accept these grand titles from elite bodies overseas. He gave a partial explanation, saying “By the Prussian knighthood I do feel honored; in the other I should not.”11 Perhaps remoteness played a part, too: he knew he would never be called upon to wear the lavish robes or take part in the elaborate ceremonies.

  Until his final retirement, Faraday traveled from Hampton Court to the Royal Institution most days and, from 1860, had a new visitor. James Clerk Maxwell had taken up a post at King's College in the Strand and lived in Kensington, so his daily journey to work took him close to Albemarle Street. He attended some of the Friday Evening Discourses and, at Faraday's invitation, gave a memorable one himself. There is no documentary record of their having met informally, but we can be fairly certain that they did, and it is pleasing for us to picture them together, two modest and genial men whose combined endeavors changed the world.

  Gradually, from 1862 onward, Faraday's health deteriorated and his mental grasp of what was going on around him crumbled; the present and the past were equally confused in his mind. In a last letter to a close friend, he wrote:

  My Dear Schönbein,

  Again and again, I tear up my letters, for I write nonsense. I cannot spell or write a line continuously. Whether I shall ever recover—this confusion—I do not know. I will not write anymore. My love to you.12

  Willpower was no longer enough to keep a hold on day-to-day events, and the haze that he had so far been able to dispel now enveloped him. He spent most of his days sitting silently, and on fine evenings enjoyed watching the sunset through the window. He died peacefully in his chair in August 1867. In accordance with his wishes, his funeral was “strictly private and plain.”13 He was buried in Highgate Cemetery, and the headstone at his grave reads, simply:

  Michael Faraday

  Born 22 September 1791

  Died 25 August 1867

  True to his words, he remained plain Michael Faraday to the end.

  Heartfelt tributes to Michael Faraday came from all over the world. They could fill a book. One from John Tyndall, who knew him as well as anybody, gives us an extra insight into Faraday's character:

  We have heard much of Faraday's gentleness and sweetness and tenderness. It is all true but it is very incomplete. You cannot resolve a powerful nature into these elements, and Faraday's character would have been less admirable than it was had it not embraced forces and tendencies to which silky adjectives “gentle” and “tender” would by no means apply. Underneath his sweetness and gentleness was the heat of a volcano. He was a man of excitable and fiery nature, but through high self-discipline he had converted the fire into a central glow and motive power of life, instead of permitting it to waste in useless passion. “He that is slow to anger” saith the sage, “is greater than the mighty and he that ruleth his own spirit than he that taketh a city.” Faraday was not slow to anger, but he completely ruled his own spirit, and thus, though he took no cities, he captivated all hearts.14

  Despite the universal acclamation of Faraday's scientific work, his greatest achievement had been largely ignored during his lifetime and was only beginning to surface at the time of his death. The great German physicist Hermann von Helmholtz made this tribute in 1881:

  Now that the mathematical interpretation of Faraday's conceptions regarding the nature of electric and magnetic forces has been given by Clerk Maxwell, we see how great a degree of exactness and precision was really hidden behind the words which to Faraday's contemporaries appeared either vague or obscure; and it is in the highest degree astonishing to see what a large number of general theorems, the methodical deduction of which requires the highest powers of mathematical analysis, he found by a kind of intuition, with the security of instinct, without the help of a single mathematical formula.15

  A man of equal stature and complementary talents was needed to reveal Faraday's full greatness. That man was James Clerk Maxwell.

  Far away from the smoky, noisy streets of Faraday's L
ondon, the Vale of Urr nestles amid the gently rolling hills of Galloway in southwest Scotland. It was there that young James Clerk Maxwell took his first steps and spoke his first words. His father had inherited an estate that came to be called Glenlair, a tranquil and beautiful place, its fields and woods traversed by the rippling waters of the Urr. Though Maxwell spent much of his life elsewhere, he remained a country boy at heart, rooted in the land and at one with those who worked on it. Glenlair was more than a charming piece of countryside; it was his home—a source of inspiration and of solace when needed. To understand Maxwell, we need to look a little into the history of Glenlair and its people.

  Things had not always been so peaceful. A couple of centuries earlier, the Galloway estate, then much larger and called Middlebie, was one of the strongholds of the fierce Maxwell clan that had ravaged the border country in bitter rivalry with the Johnstones. The Clerks of Penicuik, near Edinburgh, were, by contrast, a distinguished family with impeccable credentials. The two seemingly incompatible dynasties came together in the mid-1700s when the Clerks acquired Middlebie by marriage, on condition that whoever inherited the estate would add Maxwell to his name. As the Clerks already had their own baronetcy of Penicuik, they arranged that Penicuik would be passed to the senior heir and Middlebie to the second. So it came about that James's father was John Clerk Maxwell of Middlebie while his uncle was Sir George Clerk of Penicuik.