by John Gribbin
Mr. Hooke produced the representation of the figure of the arch of a cupola for the sustaining of such and such determinate weights, and found it to be a cubico-paraboloid conoid; adding that by this figure might be determined [i.e. solved] all the difficulties in architecture about arches and butments.
At that time, Wren was about to become deeply involved in the project for which he is best remembered, the new St Paul’s Cathedral. Before the Fire, he had already been involved in schemes to repair the old St Paul’s, including drawing up plans for a new dome based on a double structure, with an inner dome made of brick and an outer dome made of timber covered with lead, to combine strength with an elegant shape viewed from outside. After the Fire, the dream that the old cathedral might be saved persisted among many of the King’s advisers, and Wren became increasingly exasperated by being asked to work on proposals that he felt were futile, and for which, in any case, no funds were available. On 24 May 1668, he wrote to the Dean of St Paul’s (and later Archbishop of Canterbury), William Sancroft, making it clear that he had had enough, and would not be willing to take responsibility for the complete rebuilding of the cathedral (which it was now recognised was necessary) until the authorities had given him a budget (‘silver’) to work with. Using an architectural analogy, he said:
it is silver upon which the foundation of any worke must be first layd, least it sinke while it is yet rising. When you have found out the largeness and security of this sort of foundation I shall presently resolve you what fabrick it will bear.
There were still further delays before the site was cleared and the project for a new cathedral could go ahead, but on 12 November 1673 the King at last issued a ‘Commission for rebuilding the cathedral church of St Paul, London’. Wren, of course, was to be its architect. The long saga of the construction need not concern us here (it was not completed, in the sense that the cross was set up, until 1711), but it is noteworthy that Hooke’s diary records more than a hundred visits to the site between 1672 (when the demolition of what was left of the old cathedral took place) and the end of 1680, indicating his role as an assistant and adviser to Wren on his ‘Cousin’s’ greatest venture. The most important piece of advice concerned the dome of the cathedral.
At the start of the project, Wren was still thinking in terms of a double dome like those of Florence and Byzantium – no such structure had been attempted in England at that time. But Hooke had a better idea. Thinking about the problem of making the dome as light as possible, he hit on the idea of extending his work on arches. Instead of a single chain dangling between two points, he took a fine mesh, like chain mail, fastened around its rim and hanging to make a curved bowl. Inverting this bowl shape would, just as with the single chain, convert the tension forces into compression forces, and ensure stability to the domed structure. But suppose you didn’t want a simple bowl shape. Hooke had the answer. If you added little weights to the hanging mesh, and additional links to the mesh as necessary, you could alter its outline as you required, to achieve the aesthetically pleasing result you sought. Supporting the inverted structure would ensure that it retained its shape with minimum weight. Wren was delighted. On 5 June 1675, Hooke wrote in his diary ‘At Sir Chr Wren … He was making up my principle about arches and altered his module [model] by it.’
But Hooke did not go public with the idea. Instead, in 1676, in what would otherwise have been a blank space at the end of the printed version of one of his Cutlerian lectures, he added a coded message that reads, when unscrambled, ‘As it hangs in a continuous flexible form, so it will stand contiguously rigid when inverted.’
Perhaps he should have made more fuss about his contribution. The resulting dome of St Paul’s has been described by Edmund Hambly, one-time President of the Institute of Civil Engineers,fn13 as:
A masterpiece of structural engineering. It is like an egg-shell in comparison with Brunelleschi’s fine dome for the Duomo in Florence.
And it is Hooke’s dome, albeit Wren took the idea and made it concrete. The Monument is impressive enough, but the best monument to Robert Hooke the architect is the Dome of St Paul’s Cathedral.
CHAPTER FOUR
MEANWHILE …
What else was Hooke up to in the decade following 1666, the happiest years of his life? At last, we can begin to fill in some details of his domestic and personal life, because many of his letters from the mid- to late 1660s survive, and he started keeping a diary in 1672. This first diary runs until 1683, and a second one starts at the end of 1688 and finishes in August 1693. The material has been dissected and summarised by Lisa Jardine. But Hooke’s diary was not a narrative description of his life, like the famous diary of Samuel Pepys; rather, it was a set of brief notes, often written a few days after the events, to provide a reminder to Hooke about what had been going on when. It sometimes lapses into pejorative comments about people, such as his nemesis Henry Oldenburg, but is mostly a factual and straightforward account, even down to details of his sexual activity.
We do not intend to go into great biographical detail, since our main interest is Hooke’s scientific work and its significance, but a flavour of Hooke the man may help to bring him out of the shadows. Although required by the rules of the Gresham professorship to remain ‘celibate’, and living in the college, Hooke had a variety of people sharing his accommodation during his most active years. First, of course, there were the servants. At the time the diary begins, in 1672, the servant was a girl called Nell Young; with scientific detachment, Hooke recorded their sexual encounters in his diary with the astrological symbol for Pisces: )-(.fn1 Presumably there had been other servants on the same intimate terms before the time the diary began. Nell had connections on the Isle of Wight, and may have been the sister of John Hooke’s servant. When Nell married and left his employment in the summer of 1673, they remained on good (but seemingly platonic) terms, and she passed on news to him of events on the island. She lived near the Fleet Ditch and took in needlework, including making or mending clothes for Hooke. After Nell left, a succession of less satisfactory servants followed. Bridget, Doll and Bette didn’t last long (though long enough for the odd sexual encounter), but in September 1674 Mary Robinson arrived and stayed as his servant, with no mention of sexual shenanigans.
Hooke’s household also included lodgers. Richard Blackburne, a Cambridge graduate, was in residence from December 1672 to November 1673, before going to Leyden to study medicine. He was replaced by Harry Hunt, who was a kind of apprentice. Hooke trained Hunt to be his assistant, so successfully that in 1676 he became the Royal Society’s ‘Operator’, at a salary of £40 a year. They remained friends for life. This is the most notable example of the way Hooke was eager to pass on his knowledge and skills to the next generation, seemingly without any jealousy or fear of being superseded. One of his other lodger/assistants was Thomas Crawley.
Two of Hooke’s young relatives from the Isle of Wight also came to stay with him, with a view to improving their education and prospects. His niece, Grace, arrived some time in 1672, when she was twelve years old – possibly Nell came with her. In July 1675, Tom Giles (also spelled Gyles), who was the grandson of Hooke’s uncle (also Thomas Gyles, Hooke’s mother’s brother), was taken in to be educated with a view to becoming a ship’s navigator. We don’t know his exact age, but although Hooke described him as lazy and threatened to send him home to the island in March 1677, he softened when the boy burst into tears, and allowed him to stay. When Tom developed smallpox and died in September that year, Hooke called three doctors in to tend to him, and was deeply distressed when their efforts proved worthless.
Hooke’s relationship with Grace was deeper, and longer lasting, but would ultimately prove even more distressing. Her story extends into the 1680s and serves as a background to the discussion of Hooke’s scientific life in the 1670s and beyond. At the time she arrived in London, her father John, Robert Hooke’s brother, was a respected member of the community on the Isle of Wight. He had twice been Mayor
of Newport. But he was never good with money, and had already borrowed from his increasingly wealthy younger brother. Robert Hooke, of course, was highly respected in City circles through his work following the Fire, and was on good terms with Sir Thomas Bloodworth, who had been Lord Mayor at the time of the Fire. It seems that a betrothal had been arranged between Grace and the son of Sir Thomas, and she was to be educated and polished to become a suitable consort for the scion of such a family. But that, of course, would involve Grace taking with her a dowry, presumably to be provided by Robert. Early in September 1672, Hooke’s diary records ‘Bloodworth here, when he resolved to continue to have Grace and to send me his dymands next day.’
There is no hint of any problems with the arrangement until July 1673, when Bloodworth initiated steps to cancel the betrothal. By then, Grace, now thirteen, was back on the Isle of Wight. The legal process of untangling the betrothal was complicated, and not completed (by Hooke, acting on behalf of Grace and her father) until 17 September 1675, when she was fifteen. Meanwhile, Grace had been spending some time on the Isle of Wight, and some in London, where Hooke bought her fine clothes and other presents. In April 1676 she seems to have settled in London and begun once again a more concerted effort at education for life there as a ‘Lady’, including studying French. Hooke often took her out, and although as a pretty and vivacious young girl she had plenty of other admirers, in October 1677, when Grace was sixteen or seventeen, and he was forty-two, the symbol )-( begins to appear next to her name in his diary.
The age difference between the two would have been unremarkable in those days, but even in Restoration England their relationship, while not illicit in terms of the civil law, could certainly have caused problems with the ecclesiastical authorities. It seems to have been either ignored or accepted by contemporaries (such as Pepys), but in August 1677, perhaps because Hooke felt guilty and intended to end the relationship, Grace went back to the Isle of Wight and Hooke wrote in his diary (10 August) ‘Cousen Grace into the Countrey’. Jardine suggests that his use of the word ‘cousen’ was a reminder to himself that ‘their relationship was verging on the improper’. But Grace’s return to the island proved a disaster.
Grace was a beautiful seventeen-year-old girl, fashionably dressed, brought up in the ways of Restoration London, and already (thanks to Hooke) sexually experienced. The Governor of the Isle of Wight, Sir Robert Holmes, was a rogue with a roving eye. On 31 October, Hooke heard from Nell the island gossip that ‘Sir R. Holmes courting Grace’. ‘Courting’, of course, was a euphemism. On 3 November, Hooke wrote to his brother ‘about Grace and Sir R. Holmes’, but the letter has not survived. The next mention of her in the diary, on 26 February 1678, tells us that Grace is confined to bed with ‘measles’. And the next day, Hooke’s brother John committed suicide.
Any reconstruction of the events leading up to John’s death must be speculative, but the most probable explanation is that Grace had been made pregnant by Holmes. John Hooke is known to have suffered from bouts of depression, and in February 1678 he was deeply in debt, not least to Robert. Robert Hooke was always generous with his money, lending to people such as the impecunious John Aubrey with no expectation of ever getting his money back, although he always kept careful records of how much had been lent (he was a meticulous record-keeper in all aspects of his life). He would have regarded the ‘loans’ to his brother as gifts, but John would doubtless have been ashamed of the need to beg off his brother, and also owed money elsewhere, not least to Newport Corporation. His daughter’s pregnancy, removing any prospects of her achieving a good marriage, may have been the last straw.
As if this were not bad enough, there was worse for his family. As a suicide, John Hooke’s property would be forfeit to the Crown. Robert Hooke immediately went to Court to beg the King to waive his right to the estate – it is a sign, incidentally, of Hooke’s status that he was able, with the help of Wren, to gain almost immediate access to the King – and found that Sir Robert Holmes had already made the same request on behalf of Grace and her mother. It is pretty obvious why Holmes should have felt it his duty to help. The appeal was successful, but Hooke still had to sort out his brother’s estate, pay off his debts, and look after Grace, who was now a ‘fallen woman’ with no prospects except as a servant. The obvious solution was for her to return to London, which she did in May 1678, nine months after her first encounter with Sir Robert Holmes, and become Hooke’s official (paid) housekeeper, and unofficial mistress.
Meanwhile, back on the island, Holmes acknowledged that he was the father of a baby girl, who became known as Mary Holmes, and was brought up in his household. Holmes never married, and when he died he left his entire estate to a nephew, on condition that he married Mary, which he did. The union produced sixteen children.fn2 The mother of Mary Holmes has never been officially identified; we leave you to draw your own conclusions.
In London, Hooke and Grace settled into what seems to have been a happy and at least affectionate and, certainly on his part, loving relationship, which forms the backdrop to his life up until 1687, when Grace, still only in her late twenties, died after a short illness. Hooke, who was then fifty-two, was devastated by the loss, and, coupled with other events in the scientific world at that time, this at least temporarily plunged him into a state of gloom. According to Richard Waller, who knew him in later life, he was ‘observ’d from that time to grow less active, more Melancholly and Cynical’, but this may have been an exaggeration (see Chapter Nine).
But that is getting ahead of our story. In the 1670s, Hooke was certainly active, and by no means ‘Melancholly and Cynical’. Hooke’s activities were so varied that it is impossible to reconstruct a ‘typical’ working day (all his days were working days, although New Year’s Day was reserved for making up his accounts and taking stock of his life, and Sunday was similarly devoted to administration). But with the aid of ‘Espinasse’s study of his diaries, and some similar investigation by Steven Shapin,fn3 we can give some idea of just how active he was. Hooke was an early riser, if he had properly been to bed at all, and after a modest communal breakfast with his lodgers or resident assistants before Grace was up and about, he was ready to start work. During the rebuilding of London, this might involve one or more views in the morning, but when this work lessened his mornings were devoted to devising experiments requested by the Royal, preparing lectures, working on his own mechanical contrivances, and maybe architectural work.
In the afternoons, Hooke was out and about as much as his other commitments permitted. He often visited Robert Boyle at Lady Ranelagh’s house, where Boyle now had a laboratory. He visited booksellers, bought an inordinate amount of ‘medicine’ from apothecaries, and frequented makers of good-quality clothes and shoes. Hooke was no dandy, and seems to have dressed plainly (usually in black), but with excellent taste and sparing no expense. At a time when Hooke’s protégé Harry Hunt made a decent living as the Royal’s operator at £40 a year, Hooke was happy to pay one pound a yard for black cloth for a suit, and then to add black ribbon to trim it at sixpence a yard. Black silk stockings cost 11 shillings and sixpence, while a beaver hat cost £3. But his biggest sartorial outlay was on shoes. As he walked everywhere and kept no carriage, he had his shoes made to measure and of high quality. And as well as his book habit, he spent large amounts on scientific equipment. He could well afford it. He was, of course, paid in cash, and from time to time after making up his accounts he would lock some of the money away in a large chest – the usual procedure of affluent people in those days before the advent of secure banks and safety deposits.
On his walks around London, Hooke frequented many of the coffee houses and taverns, where he met – sometimes by appointment, sometimes by chance – friends and colleagues from the worlds of science, surveying or the mechanical arts. These meetings were a mixture of work and pleasure. As we have noted, surveying work was sometimes discussed over a coffee; sometimes the subject under discussion might be flying machines, or gravi
ty. The diary shows that between 1672 and 1680 Hooke visited some sixty coffee houses and more than seventy taverns, but until 1677 his favourite was Garraway’s, in Exchange Alley, close to the archetypal Pasqua Rosa’s. This was just five minutes’ walk from his rooms. But in July 1677 a new coffee house, Jonathan’s, opened just around the corner from Garraway’s. Hooke and his friends soon switched their allegiance there. For more than a decade, Jonathan’s was a centre of scientific discourse; it later became the haunt of financial speculators and stock dealers. But during Hooke’s time, when the Royal Society itself became irksome for one reason or another, Hooke and his like-minded scientific friends would get together as an informal science club to meet there in more congenial surroundings.
Hooke’s social life largely took place outside his rooms at Gresham College, at places such as Jonathan’s or on visits to people such as Boyle and Wren. Indeed, Hooke’s diary contains so many references to meetings with Wren that it is one of the prime sources used by Wren scholars. Hooke was a popular man about town, but seldom entertained at home; the convention of the time was that those regarded as lower on the social scale should call on those higher up, but not the other way around. And in many ways Hooke was a stickler for convention. Even in his private diary he referred to people by their proper titles – Lord Brouncker, Mr Boyle, and so on. Wren was Dr. Wren until receiving his knighthood, after which he is Sir Ch. Wren.fn4 Hooke knew his place, and was happy to defer socially to his superiors, but equally insisted on the respect due to his own status. Although he did not entertain in the way his social superiors did, he did have a few visitors – including John Aubrey, who sometimes needed a place to stay, and on a more regular basis Theodore Haak, a German-born scientist and FRS with whom Hooke regularly played chess until Hack died in 1690. Clearly, Hooke was (at least until Grace died) gregarious, sociable and well liked, as well as being highly respected. Jardine has described him as:
