Professor Maxwell's Duplicitous Demon

by Brian Clegg

  Engraving of Maxwell from c. 1890, taken from an 1870s photograph by Fergus of Greenock.

  Getty Images

  The last second home

  The Maxwells set up a new second home in Cambridge in the spring of 1871 (this despite an off-putting letter from George Stokes who wrote, ‘I am afraid you will find a good deal of difficulty in getting a house in Cambridge. The supply is hardly equal to the demand.’). Somewhat less imposing than his London residence, 11 Scroope Terrace was (and remains) a handsome three-storey townhouse. The Maxwells would spend the university terms and Christmas vacation at Scroope Terrace for the rest of Maxwell’s life, returning to Glenlair for the warmer summers.

  The new position of Professor of Experimental Physics was not initially an idea fit for the complex structure of Cambridge University, where the individual colleges were bodies with considerable power in their own right. At the time, the vast majority of the teaching load fell on college lecturers and private tutors. Although there were a number of university professorships, they were set up by individual endowments each with their own set of rules, though those rules had become at the least bent over the years – so, for example, the Lucasian Professor of Mathematics, a position held by Isaac Newton and more recently by Stephen Hawking, has almost from the beginning tended to have more of a theoretical physics orientation than was perhaps first envisaged.

  When Maxwell took his university position, some colleges had lecturers covering physics already, so he found himself to an extent in competition, with the added negative factor that students were generally expected to pay to attend lectures outside their college. Over time, the system was improved to pull together the college and university lecturing so that eventually it reached the stage where lectures were provided by the professors and lecturers of the university, while the colleges provided tutorials in the form of ‘supervisions’ – but during Maxwell’s time this was a system in transition, making a more difficult fit for his role within the university’s structure.

  It didn’t help that while the university recognised that someone in Maxwell’s position should not be over-burdened with actually giving lectures, expecting most of his time to go on his own research and administration, the glacially slow university administration did not make it easy for Maxwell to take on an assistant lecturer or ‘demonstrator’. Before there was even a building to give a lecture in, Maxwell did suggest one John Hunter for the post, but the university seems to have shown little interest in the appointment.

  It was possibly just as well, as Hunter was not in good health (he died a year later), though he did have an appropriate background as he had worked with both Thomson and Tait and had held his own professorial chair at Windsor College, Nova Scotia until he found the low temperatures there unbearable. But Maxwell seems to have suggested him more on the strength of their Scottish connection than any familiarity with Hunter’s skills. He wrote to his friend Peter Tait, who knew Hunter better:

  I only know him as the man who charges charcoal with bad smells.† Would he be a good demonstrator at Cambridge? I have no doubt that a man who could occlude a fishy fume in a burnt stick could also floor a demon,‡ which I suppose to be the essential part of the of fice.

  In the end, the first demonstrator, a recent Cambridge graduate called William Garnett who was later Maxwell’s joint biographer with Lewis Campbell, would be appointed in 1874.

  There was also the difficulty of winkling the components of physics out from the other subjects to construct a separate discipline. At the time, what we would now consider to be physics was largely housed within the Mathematical Tripos, but parts of it also were found in the Natural Sciences Tripos, which covered chemistry, mineralogy, geology, botany and zoology. Physics would end up as a separate discipline in the Natural Sciences Tripos, taking to itself the parts of chemistry that dealt with heat and electricity (and later the structure of atoms and molecules) and adding in many of the areas previously considered as part of mathematics, such as the science of moving bodies and astronomy.

  Even today, the split is not entirely clear at Cambridge. Experimental physics sits firmly in the Natural Sciences side, but the Department of Applied Mathematics and Theoretical Physics (for many years the academic home of Stephen Hawking) straddles Natural Sciences and Mathematics.

  The power of the Mathematics Tripos was considerable. Senior Wranglers were feted as national heroes, with their school and home town often having a holiday or procession to celebrate their achievement. This meant that the best minds were reluctant to stray from Mathematics into what were considered the less stellar regions of Natural Sciences. (When Maxwell arrived at Cambridge, Natural Sciences could not offer an honours degree, which was only available in Mathematics and Classics.)

  George Bettany, a Natural Sciences graduate from Maxwell’s day, wrote in Nature in 1874:

  The great hindrance to the success of the Cavendish Laboratory at present is the system fostered by the Mathematics Tripos. The men§ who would most naturally be the practical workers in the laboratory are compelled to refrain from practical work if they would gain the best possible place in the [Mathematics] Tripos list. Very few have courage so far to peril their place or to resign their hopes as to spend any valuable portion of their time on practical work.

  It would take a good fifty years for the differences and difficulties of the split to be fully resolved, and the relative importance of the Mathematics and Natural Sciences Tripos to be rebalanced, though throughout that period, with the work of one of Maxwell’s successors, J.J. Thomson,¶ and others, it became impossible to ignore the importance of experimental physics.

  The very need for a physical laboratory also took some accepting in a university that considered it somehow to question the sanctity of intellect if it were necessary to resort to experimental proof. As Maxwell’s Cambridge contemporary, the mathematician Isaac Todhunter, remarked of the science student:

  If he does not believe the statements of his tutor – probably a clergyman of mature knowledge, recognised ability, and blameless character – his suspicion is irrational, and manifests a want of the power of appreciating evidence.

  By the time Maxwell was appointed, Edinburgh, Glasgow, London, Manchester and Oxford had physics teaching laboratories, though only Glasgow under William Thomson and Oxford under a Professor Clifton had new buildings that had been designed for the purpose, which Maxwell wasted no time in visiting.

  Ancient lights and modern physics

  The site chosen for the new Cambridge laboratory was, frankly, not ideal.|| For a number of years, the site of the former Botanic Gardens in central Cambridge had been gradually taken over as a hub for most of the other natural sciences, forming what is now known as the New Museums Site. This seemed the logical location for Maxwell’s laboratory, but the remaining free space there was very limited. The new laboratory would loom across the narrow Free School Lane so tightly that Corpus Christi College, on the opposite side of the lane, claimed a loss of ancient lights and made a failed attempt to sue the university.

  Maxwell engaged a relatively unknown architect, William Fawcett, whose experience to date had largely been in church architecture, though Maxwell seems to have damped down Fawcett’s enthusiasm for Gothic frills; the architect largely limited his flights of fancy to the decorated main gate, carrying the Cavendish coat of arms, a statue of the Duke and the biblical inscription Magna opera Domini exquisita in omnes voluntates ejus (‘The works of the Lord are great: sought out of all them that have pleasure therein’ – Psalm 111, verse 2).

  Despite the limitations of the site, Maxwell’s design for the Devonshire building, as it was initially called, proved a triumph, with experimental physics underway three years after Maxwell was brought on board, and lectures starting in October 1872 before construction was finished. Maxwell wrote to Lewis Campbell on 19 October 1872:

  Lectures begin 24th. Laboratory rising, I hear, but I have no place to erect my chair, but move about like the cuckoo, d
epositing my notions in the chemical lecture theatre 1st term; in the Botanical in Lent and in Comparative Anatomy in Easter.

  An interesting insight into Maxwell’s thinking can be obtained in an extract from a letter to Katherine written on 20 March 1871, where he observed:

  I think there should be a gradation – popular lectures and rough experiments for the masses; real experiments for real students; and laborious experiments for first-rate men like Trotter, Stuart and Strutt.

  The next day, Maxwell wrote to William Thomson, one of the few physics professors in the UK to already have a laboratory, asking for his opinion on the requirements for ‘material accommodation’. Maxwell provided Thomson with a list for his consideration which gives us an effective insight into the kind of facilities the Cavendish would provide:

  Lecture room taken for granted.

  Place to stow away apparatus dO.**

  Large room with tables &c for beginners at experiments, gas and water laid on &c.

  A smaller place or places for advanced experimenters to work at experiments which require to be left for days or weeks standing.

  A place on the ground floor with solid foundations for things requiring to be steady.

  Access to the roof for atmospheric electricity.

  A place with good ventilation to set up Groves or Bunsens batteries without sending fumes into the apparatus.

  A good Clock in a quiet place founded on masonry, electric connexion from this to other clocks to be used in the expts and from these connexion to machines for making sparks, marks on paper &c.

  A well constructed oven, heated by gas to get up to a uniform high temperature in large things.

  A gas engine (if we can get it) to drive apparatus, if not, the University crew in good training in four relays of two, or two of four according to the nature of the expt.††

  For his ‘popular lectures’, Maxwell would build a 180-seater lecture theatre, for the dedicated experimental physics students a teaching laboratory with ten workbenches … and for the ‘firstrate men’ a number of smaller rooms where they could run their experiments undisturbed by the hurly-burly of undergraduate experimental sessions. It was in the detail of designing these spaces that Maxwell really led the field. For example, the lab workbenches were cushioned from the floor to prevent vibration from influencing experiments. Metal pipes were always visible so that those undertaking electromagnetic experiments could avoid them, and a vacuum system was available throughout the building. Cast iron hollow bricks were built into the walls at intervals to support apparatus, while ceiling joists had to protrude through the plaster so that supports could be fixed to them. There were even especially wide external window ledges, still visible on the building, so that heliostats – devices that tracked the Sun and kept a supply of bright light flowing into the building – could be stationed on them.

  Maxwell’s suggestion of enabling the serious scientists to have separate facilities seemed very much in line with the thinking of Coutts Trotter, the Trinity College physics lecturer, who wrote to Maxwell in April 1871:

  There is no doubt much to be said for natural selection‡‡ but will not the struggle for existence between the men who want the rooms darkened and the men who want their rooms light, the men who want to move about magnets and the men who want to observe galvanometers be unduly severe?

  A concern for this kind of conflict comes through in the way that Maxwell organised the smaller rooms by the type of measurement required, to avoid interference between experimental needs, rather than the traditional topic orientation used in earlier laboratories.

  A slow start

  The Cavendish Laboratory – the name change was suggested by Maxwell to commemorate both Henry Cavendish and their present-day benefactor – was officially opened in June 1874 and helped Cambridge to become Britain’s leading university for work in physics. During the next hundred years, many major developments from splitting the atom to the discovery of the structure of DNA would occur in Maxwell’s laboratory.

  It would be unfair, though, to suggest that the Cavendish under Maxwell went from nothing to a thriving establishment overnight – and some clearly doubted Maxwell’s ability to make a difference. It’s notable that an 1873 editorial in the journal Nature did not hold out a lot of hope for the Cavendish:

  Let any one compare Cambridge, for instance, with any German university; nay, with even some provincial offshoots of the University in France.§§ In the one case he will find a wealth of things that are not scientific, and not a proper laboratory to work in; in the other he will find science taking its proper place in the university teaching, and, in three cases out of four, men working in various properly appointed laboratories, which men are known by their works all over the world.

  Although Maxwell laid the foundations for the future success of the Cavendish, the laboratory was constantly underfunded during his tenure. He could not, for example, afford the essential services of a technician full-time – once a Robert Fulcher had been assigned to the post in 1877, it was on a freelance basis that soon saw Maxwell losing much of Fulcher’s time to other departments.

  Initially there was no real system to the teaching – lectures and classes were provided, but that was not a clear experimental physics component to the undergraduate Natural Sciences degree. Each year, though, Maxwell did deliver a lecture course, covering heat and matter in the first (Michaelmas) term, electricity in the second (Lent) term and electromagnetism in the third (Easter) term. The content of the later lectures seems to have been based on his Elementary Treatise on Electricity, which became a widely-used textbook.

  Despite the large laboratory being built for teaching purposes, it was primarily used so that anyone available – whether undergraduates or not – could contribute to the boring parts of research on behalf of the senior physicists – for example, in Maxwell’s ongoing attempts to standardise electrical units. It was only around 1879, with numbers on the undergraduate course rising to around 30, that regular practical experimental physics classes were implemented.

  Similarly, there was at the time no good structure to support postgraduate staff in the laboratory. It was hard to get a college fellowship based on a scientific subject, and when they were obtained they rarely lasted long (as had been the case with Maxwell’s own fellowship at Trinity – though he would have been seen as a mathematician). The position of fellow was often thought of as a stepping stone to a more significant position. It could only be held by unmarried men, and anyone staying on longer than seven years had to be ordained in the Church of England.

  When postgraduates started to become more common after Maxwell’s time they mostly had the more respectable Mathematics degrees, which made it easier to get a fellowship position than a degree in Natural Sciences. At the time the whole system was biased in this direction. Experimental physics, even then, required more assistance than did the lonely work of the mathematician. But college fellowships went primarily to those who produced an outstanding dissertation in the Mathematics Tripos, and this was obliged to be a solo piece of work. It would be a few decades before the Cambridge system fully accepted the need to bring through post-doctorate students and fellows from the Natural Sciences Tripos.

  Women in the laboratory

  Despite his support for Katherine helping with his work when at home, Maxwell was a man of his time and he was initially extremely doubtful about allowing women students into the laboratory. The first women’s college at Cambridge, Girton, had been established remotely in Hitchin in 1869 and opened at Girton on the outskirts of Cambridge in 1873, though initially the students were not members of the university. A striking illustration of the way that women were treated in the university is the way they were dealt with in respect of the Wrangler listing for the Mathematics Tripos.

  As we have seen, the position of Senior Wrangler was of huge importance across the country, but the position could not be given to a woman. Women first appeared in the Tripos listings in 1882, but rather tha
n awarding them the position of a specific Wrangler they would be classed as fitting, say, ‘between the 9th and 10th Wranglers’. In 1890, Philippa Fawcett, who would later be one of the first female lecturers in mathematics, was listed as ‘above the Senior Wrangler’ – so was, in fact, entirely deserving of that coveted position, but could not be awarded it.¶¶

  Maxwell would not give permission for women to use the Cavendish for several years. Around 1874 he wrote a pair of poems|||| with the title ‘Lectures to Women on Physical Sciences’, the first about a woman participant in science, the second regarding a woman lecturer. The first introduces us to a class with one (female) member, located in a small alcove with dark curtains. The woman in this practical class is taking a reading from a Thomson mirror galvanometer, which gives Maxwell a chance to contrast his concerns about inaccuracy of measurement with the classical description of women in poems of the time:

  O love! you fail to read the scale

  Correct to tenths of a division

  To mirror heaven those eyes were given,

  And not for methods of precision.

  Eventually, in the mid-to late 1870s, Maxwell changed his mind on women being allowed into the building, though even then this seems to have been grudging. His assistant Garnett noted:

  At last [Maxwell] gave permission to admit women during the Long Vacation,*** when he was in Scotland, and I had a class who were determined to go through a complete course of electrical measurements during the few weeks when the laboratory was open to them.

  The first true class for women in experimental physics began in 1878, and women would not be admitted to the main Natural Sciences physics course until the time of Maxwell’s successor as Cavendish Professor, Lord Rayleigh.