by Lisa Jardine
On 23 January 1675, Sir Constantijn Huygens’s second son, Christiaan, who had for almost ten years been the leading scientist at the Royal Society’s French counterpart, the Académie royale des sciences in Paris, drew in his notebook a sketch of a coiled hair-spring with one end attached to the centre of the balance of a pocket watch, and wrote underneath it, ‘eureka’. The exclamation signified his triumph at having devised a method of harnessing the isochronous properties of an oscillating balance attached to a coiled spring, to allow it to be used to regulate the mechanism of a compact timekeeper, just as a swinging pendulum could regulate a clock.6
A week later Huygens sent a letter to Henry Oldenburg, secretary of the Royal Society in London, officially lodging with the Society an anagram cryptically containing the secret of his spring-driven balance. On 20 February, having heard that his French clockmaker Isaac Thuret had gone to the authorities claiming the clock he had made to Huygens’s technical specifications was his own, Huygens went public with his timekeeping breakthrough. He rapidly secured a French privilège, or patent, and published an account of it, with diagrams, in the next issue of the journal of the Académie royale des sciences.
On 20 February Huygens also wrote to Oldenburg disclosing the solution to the cipher: ‘The arbor of the moving ring [the balance wheel] is fixed at the centre of an iron spiral.’ He proceeded to enlarge on this with a verbal description:
The fact is, this invention consists of a spring coiled into a spiral, attached at the end of its middle [i.e. the interior end of the coil] to the arbor of a poised, circular balance which turns on its pivots; and at its other end to a piece that is fast to the watch-plate. Which spring, when the Ballance-wheel is once set a going, alternately shuts and opens its spires, and with the small help it hath from the watch-wheels, keeps up the motion of the Ballance-wheel, so as that, though it turn more or less, the times of its reciprocations are always equal to one another.7
London’s leading expert in timekeeper development, the Curator of Experiments at the Royal Society, Robert Hooke, learned of Huygens’s claim to be the first to invent a spring-regulated clock while dining with Robert Boyle (son of the Earl of Cork, and a distinguished scientist who had once employed Hooke as his laboratory assistant) on 25 February 1675 (old style). The following day Hooke lodged a formal complaint at a meeting of the Royal Society. He reminded the members that he had himself produced spring-regulated clocks at their meetings on several occasions in the 1660s, and declared that Huygens’s version was ‘not worth a farthing’. The affair rumbled on for several years. In the end, Huygens’s priority claim was by and large accepted, even in England. Although, in spite of Oldenburg’s best efforts, he was never granted an English patent for his balance-spring watch, he was issued with patents or licences in France and the northern Netherlands, and is today generally credited with this significant innovation in horology.
But was this really how it was? Instead of rushing to look for a ‘winner’ in the ‘race’ to find a precise longitude timekeeper (a clock accurate enough over long periods to allow calculation of a vessel’s east–west position on the open sea), perhaps we should take our cue from the draft notes for a lecture by Hooke delivered around 1676, responding to Huygens’s ‘eureka moment’, and preserved in the treasure-trove of Sloane scientific papers in the British Library. In it he queries Huygens’s claim to single-handed solution of the problem:
He should also have Remembred that Golden Rule to doe to others as he would have others doe to him & not to have vaine gloriously & most Disingenuously Indeavourd to Deprive others of their Inventions that he might magnify himself and with the Jack Daw pride himself in the plumes of others.8
In the spirit of which, and in the light of the fact that my story so far has shown that there was a free flow of ideas and culture to and fro between London and The Hague throughout the period in question, I propose to take another look at the evidence, to try to decide whether Hooke might have been right. Did that Anglo–Dutch exchange of ideas effectively amount to an international collaboration, and ought the two men in fact have been given the credit for a groundbreaking horological invention, the balance-spring regulator for a pocket watch? The story begins in the Netherlands in the 1650s, almost twenty years before Huygens’s eureka moment.
Almost a decade after the execution of Charles I, and at the height of the English Commonwealth, the Scottish courtier Sir Robert Moray and his old friend Alexander Bruce (later 2nd Earl of Kincardine) were both living in exile in the Low Countries.9 Bruce was attached to the itinerant court of Charles II, while Moray had settled in Maastricht, where he was part of a substantial English garrison assisting the Dutch Orangists to protect the southern Protestant Dutch border.10 The two were staunch Royalists whose families had been closely involved in the fortunes of the Stuarts. Now, cut off from familiar social circles, and with no likelihood (or so it seemed) that they would ever be able to return to Britain, both were occupying their spare time in recreational scientific activities – Moray had a chemistry laboratory complete with a number of stills, and both men were interested in pharmaceuticals and medical remedies.11
They were also interested in precision timekeepers. In April 1658, Moray wrote to Bruce (who was at this point in Bremen, where his family had salt and coal business interests):
I haue a second=watch can measure pulses, but no art can make a watch measure 2 minutes equally, unless yong Zulicom [Christiaan Huygens] at The Hague have found it out, who they say makes clocks that fail not a minute in 6 moneths. But this you will beleave as litle as I do, for I can demonstrate that it must go wrong to keep foot with the sun.12
A week later, Moray was able to tell Bruce (who had moved on to Hamburg) that he had now seen and handled one of the new pendulum clocks:
I have yet to tell you that I have this day seen an exceeding pretty invention of a new way of watch, which indeed I take to be the very exactest that ever was thought upon. The Rhyngrave shew it me. It is long since I heard of it, but did not expect what now I see. The inventor undertakes it shall not vary one minute in 6 moneths, and verily I think he is not much too bold. He is a young gentleman of 22, second son to Zulicon [Sir Constantijn Huygens], the Prince of Orange’s secretary, a rare mathematician, excellent in all the parts of it. I need not describe it to you till we meet, and then I believe I may get you a sight of it.13
Moray’s brief examination of the clock had whetted his horological appetite. The local Commander had shown it to him because it had a defect, and Moray could see what that was:
I find the greatest matter I have at hand to do it with, is that clock I told you of in my last. It is one of the prettiest tricks you ever saw. It stayed no longer here than just to let me see it, as if God had sent it hither of purpose. It was a good part of the time in my hands. It hath a defect and the Rhyngrave sent it to me to considder of, for all that buy them oblige themselves not to put them into workemen’s hands. I needed not look upon it long to know all was in it. I needed no more for that than the very first glance I had of it. The rest is but matter of adjusting of numbers for the wheels and pinions.
However, he had thought it best to advise that the clock be returned to its maker, Solomon Coster. But if Bruce were prepared to put up the money, he went on, the two of them together could easily construct an improved version of Huygens’s clock:
If I thought you had a mind to bestow 40 dollars or some less on one of them I would think to have it ready for you against you come. Never any other design made wanrests14 go so equally … If I make any, I will make it beat another time than this doeth, for it beats at the rate of 80 strokes of the wanrest or thereby to a minute, and I will make it beat just 60 which will be the seconds, and will put an index to shew them. But there is no end of tricks of this kind. When you come to the shop you may perhaps find there will and weal.15
Moray had clearly not at this point met Christiaan Huygens in person, but he was aware of his reputation. Since Christiaan’s father, the
diplomat and lifelong servant of the Princes of Orange Sir Constantijn Huygens, boasted about his son – his ‘Archimedes’, as he called him in letters to the eminent French thinkers Mersenne and Descartes – on every possible occasion, and Moray and he moved in the same circles, this is not surprising.16 It is likely that Bruce already knew the Huygens family too, as they were supporters of Charles II and his sister Mary Stuart, and frequenters of the social and cultural court circle of Elizabeth of Bohemia. By September that year he certainly had met Christiaan, and they had established a shared interest in maritime timekeepers. Bruce was one of the recipients of a presentation copy of Huygens’s Horologium (1658), the book in which he announced his invention of the pendulum clock.17
In any case, it is Moray who is urging Bruce to take an active interest in the new pendulum clocks, which he himself clearly understands a good deal about already. And Bruce soon had ample occasion to follow his friend’s advice.
The following year, in 1659, Alexander Bruce married Veronica van Aerssen van Sommelsdijck, daughter of Cornelis van Aerssen, Heer van Sommelsdijck, the wealthiest man, and one of the most politically prominent, in the United Provinces, and set up home in The Hague. The van Aerssens were a distinguished diplomatic family, who had served the house of Orange for three generations. They were neighbours of the Huygenses in het Plein, the smartest quarter of The Hague, close to the Mauritshuis.18 On the eve of the Restoration of Charles II, Bruce – now the Earl of Kincardine – became an extremely rich and influential man in Holland, and a family friend of one of the most celebrated horologists in Europe. He retained his Scottish rank and position also – Samuel Johnson’s friend and biographer James Boswell was a direct descendant.
From Moray’s correspondence we learn that Alexander Bruce and Christiaan Huygens began working on clocks together almost as soon as they met. In early 1660 Moray (now in Paris, probably helping negotiate the terms of the return to the English throne of Charles II), wrote responding to a description of this work by Bruce:
If all Mr Zulicom’s addition to his invention be no more but the making of a clock of the size that the pendule beats the seconds, that is every stroak takes up a second, I do not considder that of all. For I know the pendule must be about a yard long to do that, and it is believed here that all the church clock’s in The Hague are made after his way, so that they ever strike all at once, for so it hath been said here to our Queen [Henrietta Maria]. I have not seen his book, nor think it can be bought here. therefore think of sending me one. If you recommend it to Sir Alexander Hume19 and bid him send it by some of the Earl of St Albans’s servants it will come safe. If I see him here I will talk to him of his perspective glasses, and mean to make my court with him upon your account.20
So Moray and Huygens had still not met, though Moray was intent on their doing so, to discuss lenses and telescopes, and in order that he might ‘make [his] court’ on Bruce’s account.
In summer 1660, Sir Robert Moray returned to London, where he was given a senior Scottish appointment in the new government of Charles II, and became part of the close inner circle of courtiers, with lodgings within Whitehall Palace itself.21 By now Bruce has ordered a Huygens-designed clock for Moray, at his own expense, the delivery of which Moray was eagerly awaiting:
I am well pleased with Mr Zulicem’s ordering of my clock. Let it be so, and I will thank him when I see him. I have not time now to talk of that curiosity you mention,22 but where people think it needless and that those watches are best that have the pendule fast to the axeltree that hath the two pallets,23 but I am not yet of their mind, nor for that advantage he speaks of in the stoppers24 you mention. I shall onely say more of this that if the watch do not mark the inequality of the days, it goes not equally.25
Alexander Bruce and his Dutch wife, meanwhile, settled into a well-to- do international lifestyle which involved moving between the family home in The Hague, London, and Bruce’s family home (and coalmines) at Culross (Fife) in Scotland.26 In 1668, for example, Veronica’s mother, in a letter to Constantijn Huygens congratulating him on the marriage of his son Constantijn junior, tells him that she is currently staying with her daughter and son-in-law at Culross:
[Dutch] I shall be going home shortly, because the winter is coming on. I regret that I did not come here three months earlier, then I would have made a little progress with the language. [French] And I would have had the contentment of spending [more] time with the Count of Kincardine and my daughter, and this agreeable peace and civility. [Dutch] It is very beautiful and fruitful here. The Lord of Kincardine’s house lies on a high hill and the park is delightfully close by. My daughter is extremely sad that I am leaving.27
To make herself feel more at home, Veronica laid out the garden at Culross in the Dutch style, and planted it with imported Dutch tulips.
The Royal Society was established in London on 28 November 1660 by a group of scientific enthusiasts that also included John Wilkins, Robert Boyle and Christopher Wren.28 Sir Robert Moray and Alexander Bruce were founder members. The records show them to have been extremely active, usually together, in the Society’s early meetings.29 Precision timekeepers were on the agenda of these from the outset, particularly Huygens’s new pendulum clocks. The pendulum improved the accuracy of mechanical clocks dramatically: from a variance of fifteen to thirty minutes a day, to less than a minute.30 Its potential for naval and military use looked extremely promising.
Throughout the 1660s, the records of the Royal Society document a steady sequence of experiments involving pendulums and other isochronous oscillators in timekeeping.31 Moray was not the only enthusiast, but his prominent position (he chaired the meetings) meant that his encouragement of improvements to Huygens’s published designs was important.
Christiaan Huygens paid his first visit to London in April 1661, as part of the official United Provinces delegation attending Charles II’s coronation. His existing Anglo–Dutch social connections helped him to develop cordial social relations with those with similar scientific and technological interests to his own in London. Almost the first courtesy call he paid was on Bruce’s Dutch wife Veronica, to fulfil a commission from a Dutch mutual friend he had spent time with in Paris.32 The next day Bruce took Huygens to a meeting of the Royal Society at Gresham College, at which Moray was presiding, following which Dr Goddard (a prominent member) took Huygens to his Gresham rooms and showed him three handsome pendulum clocks.33
Thereafter Huygens spent much of his time in the company of Bruce and Moray, both of whom, we should remember, spoke fluent French and good Dutch and had many Dutch social connections, and other Fellows of the Royal Society.34 He did not even bother to attend the coronation of Charles II, preferring to observe a lunar eclipse with members of the Society. Bruce showed Huygens pendulum clocks of his own design, in which the Dutchman took a particular interest.35 John Evelyn tells us in his diary that he and Huygens visited the clockmaker Ahasuerus Fromanteel on 3 May, ‘to see some pendules’.36
By the time Huygens returned to The Hague in late May, a deep and lasting friendship had been established between himself and Moray, his relationship with Bruce had been consolidated, and he was also well integrated with other leading members of the Royal Society. Thereafter he took a close personal interest in advancing the cause of pendulum clocks in Britain, both scientifically and commercially. Shortly after his return to The Hague, Huygens asks Moray in a letter how the long-pendulum clock, ordered from Huygens’s clockmaker and paid for by Bruce, was performing (Moray confessed in a separate letter to Bruce a month later that he had still not had time to have it properly set up by a clockmaker);37 Huygens also helped procure clocks for Lord Brouncker, the President of the Royal Society.38 In June 1661 Henry Oldenburg paid a courtesy visit to Huygens at The Hague, on his way back to England from unspecified business in Bremen and elsewhere in the Netherlands (Oldenburg had received his university education at Utrecht). He too conducted a vigorous correspondence with Huygens following his return to L
ondon.39 There was talk of Moray and Brouncker visiting The Hague later in the same year. These plans came to nothing, but the point is, there was a regular to-and-fro of like-minded individuals, with Anglo–Dutch interests going back ten or more years, and with an interest in science, between London and The Hague throughout the 1660s.
In October 1662, Bruce arrived in The Hague on one of his regular round trips to and from his home in Culross, having used the journey in both directions to test pendulum clocks modified to his own design for their suitability as longitude timekeepers.40 According to Bruce, it was the success of these first trials which convinced Huygens that it was worth pursuing the possibility of adapting his new clocks to determine longitude at sea. He reminded Huygens later:
At my first arivall at the Hage, after the tryall I had made betwixt Scotland & [The Hague] of my watch, when you did me the favour to see me at my chamber, we fell upon the subject of the going of the pendule watches at sea; & you told me positively then that it was your opinione that it was impossible, that you hade been making experiments of it, and all the effects of them was, to be settled in that opinion by them: you did lykewise urge reasons of the impossibility of it.41
It is not clear whether Bruce’s marine clock had been built for him in Holland or England, by Dutch or English technicians, but it was certainly pendulum-regulated.42 He later told Huygens that this clock of his was the same one he had had in his possession in London eighteen months earlier when he and Huygens met there, and that it differed significantly from Huygens’s:
I came afterwards to see that watch by which you hade made your experiment; & I believe you will acknowledge that it was so farre different from mine in the whole way of it that it is not lyke they should ever have met. And the rather I thinke this, that I showed you at London 18 moneths before that tyme the same watch which receaved very small amendments thereafter; & if you hade thought that way able to bring it to passe, you might from that view have ordered one to be made for your tryell.43
