Out of the Shadow of a Giant: How Newton Stood on the Shoulders of Hooke and Halley

First, although Hooke was a paid assistant to Boyle, this was a genuine collaboration. Hooke was more than a ‘mere’ technician who did things at Boyle’s direction. This was a very unusual – indeed, possibly unique – working relationship for the time, but it is made clear in Boyle’s published works, where Hooke is regularly mentioned by name as a co-experimenter. Other assistants are not so acknowledged. Secondly, an air pump might not sound like a dramatic invention today. But in the middle of the seventeenth century it was the highest of high-tech scientific equipment, equivalent, in terms of the insights it gave, to CERN’s Large Hadron Collider, or the Hubble Space Telescope, today. It was cutting-edge technology, leading to breakthrough science. And the man who made the air pump, and made it work, was Robert Hooke, still in his early twenties. If there had been Nobel Prizes in the seventeenth century, Hooke would have walked away with one, for this achievement alone.

It all started with an experiment carried out by the Italian Evangelista Torricelli (one of Galileo’s pupils) in 1644. This seemed to shed light on a puzzle that had vexed philosophers for centuries: was it possible for a vacuum, nothing at all, to exist? One school of thought held that matter must be continuous; a rival hypothesis described matter in terms of tiny particles (atoms) moving through the void (vacuum, or empty space). Torricelli took a glass tube, closed at one end, and filled it with mercury. He then put a finger over the open end, and submerged that end below the surface of a dish of mercury before taking his finger away and raising the closed end of the tube into the vertical. Instead of all the mercury flowing out of the tube, the level dropped only until there was a column nearly thirty inches high standing above the level of the liquid in the dish, with nothing at all in the space above the column. This seemed to be the definitive proof of the reality of the vacuum, and along the way the height of the mercury in the tube was explained as a result of the pressure of the weight of the air pushing down on the surface of the mercury in the dish. Torricelli had invented the barometer, for measuring atmospheric pressure, and similar instruments were soon tested by being carried up mountains, where the lower air pressure meant that the column of mercury was shorter than at sea level. Which suggested that if the air continued to thin out, then above the atmosphere there must be empty space.

Instead of carrying the equipment up a mountain, Boyle wanted to try it out inside a vessel where air could be pumped out to lower the pressure. If he could make a vacuum inside the vessel, the level of mercury in the column would fall as the air was removed, until it would not be supported in a column at all. But first, he needed a way to make a vacuum in the laboratory. This is where Hooke came in. Otto von Guericke, in Saxony, had already made a reasonably efficient air pump, which he had used to suck air out of two large copper hemispheres that were placed together rim to rim to make a sphere, but with no mechanical fastenings at the join. With air pressure inside the sphere reduced, the pressure of the atmosphere outside squeezed the hemispheres together so tightly that in a famous demonstration made to Emperor Ferdinand III in 1654 thirty horses could not pull them apart.

Von Guericke’s pump was large and cumbersome, needing two men to operate, and, of course, there was no way to see inside his copper sphere. Boyle needed something that could be operated by one man, with a chamber made of glass through which experiments could be observed. He first approached the greatest scientific instrument maker of the time, Ralph Greatorex, in London. But his forte was making precision instruments, and his attempt at the heavier machinery required for the pump was not up to Boyle’s needs. So it was Hooke, at the end of the 1650s, who designed and built the breakthrough instrument, using funds supplied by Boyle. He went to London to oversee the manufacture of the heavy components in the workshops there (we don’t know if he worked on these himself), then had them taken to Oxford, where he put the pump together and made it work.

The vacuum chamber consisted of a glass sphere fifteen inches in diameter, known as the ‘receiver’, with a brass lid four inches in diameter, which could be opened to place apparatus inside the sphere. A tapering hole in the base of the sphere stood on top of a tight-fitting brass cylinder, sealed with a leather collar. The brass lid had a small tight-fitting stopper, sealed with oil (referred to by Hooke as ‘sallad oil’), that could be turned to tug a string attached to the stopper in order to set off an experiment inside the globe. The cylinder below the globe connected to a brass pump fitted with an ingenious rack-and-pinion system, which allowed air easily to be pumped out of or into the globe. Hooke’s pump sucked air from the cylinder using a piston that was connected to a rod cut with teeth which engaged with a gear wheel that could be wound with a handle to push the piston up, forcing air out through a one-way valve, then pull the piston down, leaving a vacuum in the tube. The piston could be pumped up and down repeatedly, sucking more and more air out of the glass vessel. This apparatus became known as ‘Boyle’s air pump’, which it was in the sense that he paid for it and owned it (just as Dolly Parton’s hair is her own). But as Boyle acknowledged, it was made by Hooke, and Hooke was the experimenter who operated it during the many investigations that followed. In the fragment of autobiography quoted by Waller, Hooke said:

In 1658, or 9, I contriv’d and perfected the Air-pump for Mr Boyle, having first seen a Contrivance for that purpose made for the same honourable Person by Mr Gratorix, which was too gross to perform any great matter.

Some idea of the significance of the pump is that, even by the end of the 1660s, there were only half a dozen comparable air pumps in Europe, and three of them had been made by Hooke.

Boyle and Hooke carried out many experiments with their pump and vacuum chamber – Boyle later described forty-three of them in his book New Experiments Physico-Mechanical Touching the Spring of the Air, published in 1660. These included burning (or attempting to burn) substances such as candles, coal, charcoal and gunpowder in a vacuum, with results that convinced them that fire was not one of the ‘four elements’ (fire, earth, air and water) as the Ancient Greeks had taught, but involved a chemical process. Candles, for example, went out when air was removed from the globe, and burning coals died away, but, crucially, reignited when air was let back in. One of the other experiments showed that water boils at a lower temperature when the air pressure is reduced. But one of their most important discoveries is hinted at in the title of Boyle’s book. Every stroke of the handle of Hooke’s air pump demonstrated the ‘spring’ of the air, just like the springiness felt when using a bicycle pump today, and Hooke set out to measure this springiness – what we now call air pressure.

Around this time, at the end of the 1650s, the Englishman Richard Towneley was carrying out experiments with a Torricelli barometer on Pendle Hill, in Lancashire. He was following the example of continental experimenters, notably Florin Périer. Like them, he found that the pressure of the air measured by the barometer is lower at higher altitude, and he surmised (without carrying out experiments to test the idea) that the pressure is less because the air is thinner – that is, less dense – at higher altitude. He mentioned this idea to Boyle, who asked Hooke to devise a way to test it.

Hooke did this in 1660 or 1661, using a long glass tube shaped like the letter J, with the top open and the short arm of the J at the bottom sealed. He poured a little mercury into the top of the tube so that it partly filled the U-bend at the bottom but left some air trapped in the closed end. With the level of mercury the same on both sides of the U-bend, the trapped air was at atmospheric pressure. But Hooke could increase the pressure on the trapped air by pouring more mercury in, forcing some of it round the bend and squeezing the trapped air into a smaller volume. Boyle was short-sighted and bad at arithmetic, so we know for sure that it was Hooke who not only designed the experiment but also made the careful observations and records that showed that the volume of the trapped air was inversely proportional to the pressure applied. Double the pressure, and the volume halves; triple the pressure and the volume is reduced to one-third, and so on. These results were published in the second edition of Boyle’s book, in 1662, and became known as ‘Boyle’s Law’, although he did not use that name himself. Hooke’s own account appeared in his book Micrographia, published in 1665:

Having lately heard of Mr. Townly’s Hypothesis, I shaped my course in such sort, as would be most convenient for the examination of that Hypothesis.

After describing the experiment (Hooke tells us that the long arm of the J-tube was about fifty inches long), he concludes:

and by making several other tryals, in several other degrees of condensation [compression] of the Air, I found them exactly answer the former Hypothesis.

The discovery itself was significant. The measurements of the springiness of the air fed into the development of theoretical ideas about the nature of matter, leading up to the idea of atoms and molecules flying about in the vacuum and colliding with one another. It also had practical implications, because the idea of making vacuums using pistons, and using the weight of air (atmospheric pressure) to compress pistons, found applications in steam engines. But from our point of view the most important thing about these experiments is the way they were carried out and reported. For the first time, experimental philosophers described their experiments in great detail, along with the way they overcame difficulties and how they interpreted their results. They not only gave a table showing the actual measurements of pressure made in the course of the investigation, but also included alongside these the numbers corresponding to ‘What the pressure should be according to the Hypothesis’. The match was not perfect; of course there were experimental errors. But they (or rather Hooke) had found that the accuracy of the hypothesis was confirmed within the limits of experimental error. And everything was laid out carefully so that other experimenters could repeat the whole process and see if their results agreed. It was only later, when many other experiments had indeed confirmed this, that the hypothesis was elevated to the status of a law, albeit with the wrong name attached to it.

While in Oxford, Hooke also developed his interests in astronomy and timekeeping, which we have already mentioned. Some of his other activities can wait until we discuss the contents of Micrographia. But there was one interest in particular that Hooke at first eagerly investigated in Oxford but then (for sound scientific reasons) abandoned – flying. This change of heart is described in the autobiography:

I contriv’d and made many trials about the Art of flying in the Air, and moving very swift on the Land and Water, of which I shew’d several Designs to Dr. Wilkins then Warden of Wadham College, and at the same time made a Module [model], which, by the help of Springs and Wings, rais’d and sustain’d itself in the Air; but finding by my own trials, and afterwards by Calculation, that the Muscles of a Mans Body were not sufficient to do anything considerable of that kind, I apply’d my Mind to contrive a way to make artificial Muscles; divers designs wherefore I shew’d also at the same time to Dr. Wilkins, but was in many of my Trials frustrated of my expectations.

The details surrounding one other project which Hooke worked on in the late 1650s and early 1660s are less clear, because for commercial reasons (in the hope, never realised, of making a fortune from his invention) for a long time Hooke kept details of his work on clocks and watches secret, and when he did report them he was inclined to exaggerate his achievement to strengthen his case. Nevertheless, it is quite clear that by about 1658 he was deeply interested in the possibility of designing an accurate timepiece – a chronometer – that would solve the problem of finding longitude at sea. This was of vital importance to an emerging maritime power such as England or their Dutch rivals.

Finding the latitude of a ship at sea was a relatively simple matter of measuring the height of the Sun above the horizon at local noon. But determining longitude was a much more difficult problem. It was clear that the person who solved that problem would certainly become rich as a result – even before the establishment of the famous prize of £20,000 offered for the solution by the British government in 1714. Hooke was always concerned about his financial security, and looked into two ways to tackle the problem. The first was based on the idea of astronomical observations, in particular observations of the moons of Jupiter. The four largest moons (discovered by Galileo in 1610) follow regular, predictable orbits around the giant planet, changing their positions relative to one another like the hands of a heavenly clock. These orbits could be predicted from past observations, even before the discovery of the inverse square law of gravity, so by studying tables of predicted patterns (in particular, eclipses of the moons by Jupiter) and comparing them with observations, a mariner could determine the time at the place where the tables were drawn up (such as the home port, or London) and compare that with the local time. Because of the rotation of the Earth, which takes twenty-four hours to complete a 360-degree rotation, local noon is one hour later for each fifteen degrees west of the home base, and one hour earlier for each fifteen degrees east (360/24 = 15); even Oxford time, by the Sun, is five minutes behind the time at Greenwich, in London. So the difference would tell them how far east or west of home the ship was. This was one of the reasons, in addition to his interest in astronomy and the nature of the Universe (Hooke was interested in everything about how the world worked!), that Hooke devoted a great deal of time to developing improved astronomical observing instruments. But making the required accurate observations from the surface of a ship at sea, pitching and rolling in the waves, was totally impractical.

The other way of working out how far east or west of, say, London you were would be to carry ‘London time’ around with you, in the form of a clock or watch set before starting out on the voyage. But that would require a chronometer that could keep time to an accuracy of a few seconds over an interval of weeks or months. And, again, it had to do so on a ship being tossed about on the waves.

In the middle of the seventeenth century, revolutionary developments in timekeeping devices were taking place. Earlier clocks, going back to the fourteenth century, were powered by slowly falling weights, connected to the gears and wheels of the mechanism by cords wrapped around a bobbin-like drum. The drum rotated as the weight fell, and the rate at which the weights fell was controlled by a so-called verge escapement, involving a toothed ‘crown wheel’ which was tugged one step (one tooth) at a time by the pull of the falling weight. When the weight reached its lowest point, it was simply lifted (or wound) back up to keep the clock ticking. These clocks were good for measuring the passage of the hours, provided they were re-set at noon, but did not even measure minutes accurately, let alone the seconds. It was Galileo who realised that the time it takes for a pendulum to complete one swing of its arc depends only on the length of the pendulum, and the Dutch scientist Christiaan Huygens who, in 1656, used this, in conjunction with a traditional verge escapement, to produce the first reasonably accurate pendulum clock. A pendulum 39.1 inches (0.994 m) long takes one second to swing one way, and one second to swing back, at 45 degrees latitude on the surface of the Earth; at one time it was proposed that this length should be used to define the metre (making a metre 39.1 inches), but this was not followed up.

Both Huygens and Hooke set out to improve on these devices, being well aware that no matter how accurate it might be on land, a pendulum clock was hardly the most practical timepiece to have on the heaving decks of a ship.

Hooke’s key idea was to replace the regular swing of a pendulum with the regular pulse of a coiled spring, vibrating in and out. He also devised an improved escapement. The spring-driven mechanism would work in a clock, but, equally importantly, could be made small enough to be incorporated in a watch compact enough to be carried in your pocket.

This is where the historical chronology becomes murky. Hooke certainly had the idea for such a watch by 1660 (the year of the Restoration, when Charles II came to the throne). But had he made a watch to this design by then? Hooke, via Waller, tells us that he had:

Immediately after his Majesty’s Restoration, Mr. Boyle was pleased to acquaint the Lord Boucher and Sir RobertMoray with it, who advis’d me to get a Patent for the Invention, and propounded very probable ways of making considerable advantage by it. To induce them to a belief of my performance, I shew’d a Pocket-watch, accommodated with a Spring, apply’d to the Arbor of the Balance to regulate the motion thereof … this was so well approved of, that Sir RobertMoray drew me up the form of a Patent … [but] the discouragement I met with in the management of this Affair, made me desist for that time.

The discouragement to which Hooke refers is a proposed clause in the patent that says that if anyone else improved upon the design ‘he or they should have the benefit thereof during the term of the Patent, and not I’. It is hardly surprising that Hooke refused to sign away his rights in this way (as he put it, it is easy to add to an existing invention), and there the matter rested until a later dispute, as we shall see, blew up with Huygens.

We know that these events took place – a draught copy of the patent survives. But did they happen in 1660, or a little later? The surviving papers are undated, which doesn’t help. Some historians suggest that it was actually in 1663 or 1664, and that Hooke later fudged the dates in order to strengthen his case against Huygens. The most careful analysis of the papers has been carried out by Michael Wright of the Science Museum in London.

He concludes that Hooke probably mentioned the invention to Moray in 1662, and revealed the details a year or two later, with the invention then being developed further in 1664, with a timekeeper completed in the summer of 1666. We shall never know for sure, and at this distance in time the priority doesn’t matter. What matters is that Hooke certainly did invent a spring-driven pocket watch, unaided, by the early 1660s, while also working as Boyle’s assistant (including the discovery of ‘Boyle’s Law’) and carrying out his own investigations of, among other things, flying, astronomy, and the microscopy that features in the next chapter. Apart from the significance of the watch itself, which was indeed a major development, two points are noteworthy about this story. The first is the way Hooke worked on many projects at once; the second is the connection with the dramatic event of the Restoration. Both would be significant in the next phase of Hooke’s career.

CHAPTER TWO (#ulink_4613194a-73f1-50d0-9725-64c5cc4941f3)

THE MOST INGENIOUS BOOK THAT EVER I READ IN MY LIFE (#ulink_4613194a-73f1-50d0-9725-64c5cc4941f3)

At the end of the 1650s, England was once again plunged into political turmoil. Oliver Cromwell died on 3 September 1658, and was succeeded by his son Richard, a less competent administrator unable to cope with a Commonwealth that was already in difficulties, with mounting debts and rival factions. In April 1659 Richard was pushed aside and the army took over, raising the prospect of another civil war. Many people who were in a position to do so, Hooke among them, started to make contingency plans. Hooke’s youthful imagination had been caught by the sight of the ships entering and leaving Yarmouth, and he now began to consider life as an adventurer and explorer travelling to the Far East. In May 1659, still not yet twenty-four years old, he read a book, Itenerario, written by a Dutch traveller, Jan van Linschoten, and made notes, which survive, about the kind of life he could expect if he followed in van Linschoten’s wake. He took particular note of the attractions of China, where ‘Schollars are highly esteemed’. But before Hooke’s plans could come to fruition – if they were ever more than a pipe dream – in the spring of 1660 Charles II was welcomed back to England, and the monarchy was restored. A wave of optimism swept the country, and Hooke, from the staunchly Royalist Isle of Wight, abandoned his plans to travel and looked forward to a future in England, where he was securely established with Boyle and had a growing reputation among the wider circle of experimental philosophers. He published his first scientific paper (as we would now call it), on capillary action, in 1661. But by then, the centre of experimental philosophy was shifting from Oxford to London.

More precisely, the scientific activity was centred around an institution known as Gresham College, in the City of London (the edifice known as Tower 42 now stands on the site, between Broad Street and Bishopsgate). In Hooke’s day, the building on that site was a large Elizabethan mansion, once owned by a wealthy merchant, Thomas Gresham. A range of buildings surrounded a square courtyard roughly a hundred yards across. Gresham had died in 1579, and left the income from his investments to have the house converted into a college and to pay for the appointment of seven ‘professors’ in perpetuity. The professors would be provided with an income of £50 a year for life, and rooms in the college, in return for giving lectures in their specialist subjects once a week in term time. The specialist subjects chosen by Gresham were law, physic (medicine), divinity, rhetoric, music, chemistry and astronomy. The professors were also required to be celibate, although as we shall see the interpretation of this term was rather loose. The status of these posts has waxed and waned over the years, but there are still Gresham Professors giving lectures, even though they no longer have a college to live in.

Hooke’s Oxford friend, Christopher Wren, had become the Gresham Professor of Astronomy in 1657, a post he held until 1661, when he returned to Oxford as Savilian Professor of Astronomy. Other experimental philosophers based in, or visiting, London (and crucially including Wilkins, who had become the Master of Trinity College in Cambridge in 1659, but was ejected when the Royalists returned to power, and was now lodging with a friend in Gray’s Inn) used to attend Wren’s lectures, and got into the habit of meeting up afterwards to discuss the topics raised and other scientific matters. On 28 November 1660, after one of Wren’s lectures, the group decided (clearly by prior arrangement) to formalise these gatherings. A record in the Royal Society archive reads:

Memorandum November 28, 1660. These persons following according to the custom of most of them, met together at Gresham College to hear Mr Wren’s lecture, viz. the Lord Brouncker, Mr Boyle, Mr Bruce, Sir Richard Moray, Sir Paule Neile, Dr Wilkins, Dr Goddard, Dr Petty, Mr Ball, Mr Rooke, Mr Wren. And after the lecture was ended they did according to the usual manner, withdraw for mutual converse.

That ‘mutual converse’ led to the resolution that they would form an association ‘for the promoting of Experimentall Philosophy’ and:

That this company would continue their weekly meetings on Wednesday, at 3 of the clock in the term time, at Mr Rooke’s chamber at Gresham College; in the vacation at Mr Ball’s chamber in the Temple, and towards the defraying of expenses, every one should, at his first admission, pay downe ten shillings and besides engage to pay one shilling weekly … Dr Wilkins was appointed to the Chair, Mr Ball to be Treasurer, and Mr Croone, though absent, was named the Registrar.

This was the beginning of the Royal Society, whose members became known as ‘Fellows’. Because of Wilkins’ reputation as a Parliamentarian, it became politic for him to take a back seat (at least formally), and Sir Robert Moray was installed as President of the fledgling association on 6 March 1661. In no small measure thanks to his skill at political wheeling and dealing, the Society gained its first Royal Charter in 1662, with Brouncker now named as President, but this Charter proved unsatisfactory (for obscure reasons), and was replaced by a second Charter in 1663, formalising the name as ‘the Royal Society of London for Promoting Natural Knowledge’.

The Society had a coat of arms, and a motto, Nullius in Verba, which can be translated as ‘take nobody’s word for it’. In other words, carry out experiments and test hypotheses for yourself, do not rely on hearsay. It would be Hooke who soon put that fine sentiment into practice. We shall always refer to the institution as the Royal Society (even for the period before the award of the first charter), the Royal, or the Society; one of the aims of seeking royal status was to get financial support from the King, which was never forthcoming, but the status did encourage rich dilettantes to offer their support, if only by becoming Fellows and (sometimes) paying their subscriptions.

As early as December 1660, the Society laid out the ground rules for doing experiments, and recognised the need for ‘curators’ who would carry out the experiments. At first, this role was carried out by the most expert Fellows (known as virtuosi), but this was not a success, and it became clear that they needed somebody who could do the job full time. In the early 1660s, Boyle was spending some of his time in Oxford and part at his sister’s house in London, where he had a laboratory. Hooke accompanied him and was well known to the Fellows (his little paper on capillary action is mentioned in their records). By 1661, Boyle and Hooke were developing an improved air pump, and Boyle gave their original pump to the Royal, where it languished with nobody able to operate it satisfactorily. This was another indication of the need for a skilled curator who could make things work. And who better than the man who had designed and built that pump?

So on 12 November 1662 Sir Robert Moray proposed, and the Fellows accepted, that Hooke should be appointed Curator of Experiments ‘to furnish them every day when they met, with three or four considerable Experiments’, as well as following up topics for investigation suggested by the Fellows. The only snag was, the Royal did not have any funds with which to pay him. The solution was that in effect Boyle ‘lent’ Hooke to the Royal Society until 1665, when a combination of circumstances (not all of them straightforwardly honest) stabilised the situation.

The Royal had notionally set Hooke’s salary as £80 a year, even though they were not paying it. Nor were they able to provide him with accommodation, so he had to make do with temporary lodgings. Partly as compensation, in recognition of his value he was elected as a Fellow of the Royal Society on 5 June 1663, with all the usual fees and subscriptions being waived. The prospect of establishing the relationship on a proper basis came in May 1664, when Isaac Barrow (the successor to the Laurence Rooke in whose rooms the Royal had its early meetings) resigned his post as Gresham Professor of Geometry to become the first Lucasian Professor of Mathematics in Cambridge (where he came across a student called Isaac Newton, who later became the second Lucasian Professor). Before he left for Cambridge, Barrow had been giving some of the astronomy lectures in place of Dr Walter Pope, Wren’s successor, who was temporarily away from London. After Barrow left, Hooke took on those temporary duties, and received the appropriate stipend, while Pope was away. Who better to be Barrow’s replacement?

There were two candidates for the post: Hooke, who had strong support from the Royal, and a physician, Arthur Dacres. On 20 May 1664, a committee (‘The Court’) met to decide between them, and duly announced their verdict:

two learned persons viz. Dr Arthur Dacres and Mr Robert Hooke being suited for the same, their petitiones being Read their ample Certificates considered and the matter debated The Court proceeded to election and made thereof the said Dr Dacres to supply the said place of Geometry Reader in the College.

A few days later, perhaps while drowning his sorrows, Hooke bumped into a wealthy merchant, Sir John Cutler, in a public house. He knew Cutler through a mutual friend, and gloomily recounted the tale. Cutler’s response was to tell Hooke to cheer up, because he, Cutler, would provide the financial support Hooke needed by creating a post for him to lecture on the History of Trades, at the same remuneration as a Gresham Professor – £50 a year. Before the arrangement could be formalised, however, the Royal Society got wind of some irregularities surrounding the appointment of Dacres. It turned out that the actual committee had voted for Hooke by five to four, but that the Lord Mayor of London, Sir Anthony Bateman, who was present as an observer but not a member of the committee, then voted for Dacres, making a tie, and followed this up by claiming the right to a casting vote in favour of his man. Bateman’s term as Lord Mayor came to an end shortly after this fiasco, and he was succeeded by Sir John Lawrence, a more straightforwardly honest man who knew Hooke’s abilities. Following formal representations by the Royal, a committee of investigation chaired by Sir John met on 20 March 1665 and concluded:

that Robert Hooke was the person legally elected and accordingly ought to enjoy the same with the Lodgings profits and all accommodation to the place of Geometry Reader appertaining.

In the months before the appeal was heard, the Royal acted with underhand cunning to secure the benefits of Cutler’s offer for themselves. On 27 July 1664, the Council of the Royal formally voted to appoint Hooke as Curator of Experiments with a salary of £80 a year, but kept this secret while they negotiated ‘on Hooke’s behalf’ with Cutler. It was agreed that Hooke would give what became known as the Cutlerian Lectures, on practical applications of science ‘to the advancement of art and nature’ but on specific topics chosen by the Royal. And Cutler’s money would be funnelled to Hooke through the Royal. So when Hooke was formally appointed as Curator on 11 January 1665, the Royal only had to add £30 a year for his income to be made up to the promised £80. The situation was compounded when Cutler (possibly piqued by this, or maybe just unreliable) failed to pay his share most of the time, leading to tedious legal hassles only resolved in Hooke’s favour after Cutler’s death, in 1696 (for the first ten years, the Royal also had trouble finding the money to pay their contribution to his salary). But still, as he did get the Gresham chair Hooke was reasonably comfortable from the time he was installed as Gresham Professor in March 1665 (he had actually been lodging in rooms in the College since the previous September). As well as the income, he had a parlour, library and two smaller rooms in a first-floor apartment, a workshop on the ground floor, cellar rooms providing further space for his experimental work, and a garret for a servant. He was able to keep at least one servant, usually a girl, and usually on more than friendly terms, as we discuss later. He was a gregarious and friendly man (at least until old age and infirmity made him more grumpy), who welcomed visitors to his home, as well as mingling with his friends in the coffee houses. At the age of twenty-nine, he was settled for life, with no need of patronage.

Hooke was a diligent lecturer, unlike many of his fellow Gresham Professors. Some didn’t even live at the College, but let out their rooms and enjoyed a quiet life in the country, or even in another country. Hooke’s duties (in addition to his work for the Royal, remember!) were to give his lectures on Thursdays in term time,

in Latin between 8 a.m. and 9 a.m. and the same lecture in English between 2 p.m. and 3 p.m. He seems to have always had the lectures prepared and been available to do his duty, but very often, as his diary records, nobody turned up to listen to them. He also gave the Cutlerian Lectures, officially during the vacations but sometimes on other occasions; many of these were collected and published in 1679. These wandered far from the original brief, which makes them much more interesting to us even if it helps to explain Cutler’s reluctance to pay Hooke.

But that is getting ahead of our story.

The year 1665 was a turning point for Hooke in other ways, but before we discuss the changes in his life that took place in the second half of the 1660s, we should go back to look at his scientific achievements in the first half of that decade.

Some idea of the breadth of Hooke’s activities can be gleaned from a ‘wish list’ he wrote at the beginning of the 1660s of the projects he had in mind: