Science Under the Microscope: More Anglo–Dutch Misunderstandings

It was not only in matters concerning pendulum clocks and balance- spring watches that Christiaan Huygens interfered in the affairs of British scientific practitioners like Alexander Bruce and Robert Hooke. In this chapter I offer a further example of the way the story of scientific advance is altered once we recognise that a Dutchman, resident mostly in Paris, and an Englishman employed by the Royal Society, were effectively engaged in a long-range collaboration, in spite of the body of water, national ideologies and differences of temperament that separated them.

In this instance, the fortunes of a set of scientific ideas depend on the movement of a copy of a published book – Hooke’s Micrographia, or Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries thereupon (1665). This reminds us that books moved around the Continent of Europe with a speed and efficiency that almost match those achieved by online booksellers today. In August 1655, for example, the antiquarian William Dugdale received a letter from Sir Edward Walker, Garter King of Arms and loyal servant of Charles II, exiled in Amsterdam. Walker congratulated Dugdale on his recently published antiquarian history book, a copy of which he had seen in the hands of a friend to whom Dugdale had sent a personal copy. In reply Dugdale wrote that ‘God be thanked that we have disposed of above 400 of these allready, (though it came out but in Easter Terme,) the one half whereof are gone beyond sea; but our money for them will not come in till ye next spring.’1

What this second example of Anglo–Dutch scientific interaction shows is the way our understanding of the trajectory of development in emerging science has tended to get deflected and sidetracked, because accounts of the scientific debate are overly preoccupied with the local communities – treated as enclosed and self-sufficient – in which those who played a leading role (in this case, the Dutchman Christiaan Huygens in Paris, and the Englishman Robert Hooke in London) worked at the time.

The end of this particular story also reminds us how political upheaval can dramatically alter the perceived importance of an individual’s work, and thus posterity’s opinion of its significance. At the Royal Society, the arrival of William III of Orange in England at the end of 1688 resulted in a significant reorganisation in every English institution, as we might expect when a foreign invasion is followed by long-term occupation. The result for the Society was a particularly dramatic version of ‘régime change’: the meteoric rise of figures hitherto of only middling importance within the institution, while others were swiftly and permanently marginalised, the significance of their scientific work downgraded and thenceforth diminished in importance in the historic records.

The design, manufacture and skilled use of microscopes, like that of clocks, developed very much in parallel, in the seventeenth century, in England and the United Provinces. To the Dutch goes the credit for initially perfecting a lens-based device which could provide a high level of magnification of objects too small to be appreciated using the naked eye.2

There is a measure of consensus amongst historians of science that the Dutch use of magnifying lenses originated in the hands of painters involved in creating ‘lifelike’ representations of natural phenomena, particularly plants and insects. The names regularly associated with the meticulous rendering of detail only accessible with a microscope are Jacob de Gheyn II and Joris Hoefnagel. Intriguingly for the present story, both men and their families were closely associated with the Huygens family. Sir Constantijn Huygens’s mother was a Hoefnagel, and he himself took lessons in miniature painting with a Hoefnagel uncle. The de Gheyns were neighbours in The Hague, and the young Jacob de Gheyn III was Constantijn’s companion on his first diplomatic visit to London. Huygens himself took a keen early interest in microscopy in the 1620s.

In the 1670s and ’80s, both Christiaan Huygens and Constantijn Huygens junior became enthusiastic grinders of lenses for telescopes and microscopes, and practising microscopists. Both corresponded with and visited the famous Dutch microscopist Anton van Leeuwenhoek in Leiden. So it is hardly surprising to find the entire Huygens family captivated by the newly published English book with which Robert Hooke’s name and reputation are most lastingly associated, Micrographia.

Although Robert Hooke’s reputation as an experimentalist and instrument-maker was already considerable at home in England in the early 1660s, he became a figure of note in the Europe-wide community of virtuosi beyond the Royal Society, particularly that in the United Provinces, with the publication of Micrographia in January 1665. The sumptuously illustrated book established his reputation in the international scientific community virtually overnight.3 Immediately it appeared, intellectuals across Europe began exchanging views on the book, and above all its magnificent engravings, in their correspondence.4

The interest of Christiaan Huygens, still at this time domiciled in the family house at The Hague, was immediately aroused when his London- based Scottish friend Sir Robert Moray mentioned Micrographia to him – and the fact that it included information on lens-making (a topic Christiaan was particularly interested in) – in January, and promised to send him a copy shortly thereafter. Moray expressed his satisfaction with the book, one of the first publications licensed by the new Royal Society, but confessed that he had not had time to do more than glance at it himself.5

On 26 February Moray dispatched a copy of Micrographia to The Hague with a covering letter, entrusting it to the English diplomat Sir William Davidson to deliver.6 Because Huygens somehow missed Davidson, however, the book and letter did not reach him until 25 March. The following day he wrote an enthusiastic letter to Moray telling him that he had had no idea the book was of such consequence, and particularly praising the quality of the illustrations and engraving.

But before the book reached him and gained his immediate respect, Christiaan Huygens had unfortunately had some less flattering things to say about Hooke’s abilities in general, based on face-to-face encounters with the Curator of Experiments while Huygens was visiting London some years earlier. Between the dispatch and arrival of his copy of Micrographia, Christiaan had formed some superficial views on it based on selected extracts from the text sent to him by his father, Sir Constantijn Huygens, who happened to be in Paris on Stadholder business in February 1665 and had swiftly obtained a copy.7 Christiaan had at this point not yet had sight of the vital accompanying engravings of a whole sequence of natural phenomena much-magnified, nor had he any idea that the illustrations were the glory of the entire publication.

Writing to his son, Sir Constantijn was full of praise for Micrographia. Christiaan, by contrast, basing his judgement on the selected extracts, expressed surprise at the ‘rashness’ of some of Hooke’s conjectures. Hooke was neither amiable, nor a good enough mathematician for his activities in any field to be taken seriously, he confided to his father: ‘Thanks for the extracts from Hooke [Micrographia]. I know him very well. He understands no geometry at all. He makes himself ridiculous by his boasting.’8

In Paris, Sir Constantijn did not keep his scientist son’s doubts about Micrographia to himself. Among the French virtuosi who seized eagerly upon Micrographia was Adrien Auzout, a talented observational astronomer and instrument-maker whose name is associated with the development of the eyepiece micrometer for long telescopes. As soon as he heard about Hooke’s book, he arranged to borrow Sir Contantijn’s copy.9 Shortly after Huygens senior had returned to Holland, Auzout wrote from Paris to Christiaan Huygens in The Hague: ‘A few days ago I received a letter from Monsieur de Zulichem [Sir Constantijn], who told me that you, like myself, had found a quantity of interesting things in Hooke’s book.’10

Auzout’s interest in Micrographia and its author began a chain of events which had a lasting effect on Hooke’s long-term reputation, largely without his own intervention or even participation. It is important to note that right at the start, Auzout had been shown Christiaan’s less than generous letter to his father about Micrographia, expressing reservations about some of Hooke’s findings and claims.

Among the ‘quantity of interesting things’ which had caught Auzout’s attention in Micrographia were those parts of the text dealing with Hooke’s technological innovations in microscope manufacture, rather than the extraordinarily minute details of natural phenomena seen under the microscope and reproduced in the plates. A description of a machine for grinding accurate lenses, interpolated into the preface, particularly intrigued Auzout, since he was already involved in a critique of a similar machine advertised by Giuseppe Campani in Italy, and was himself proposing one to the circle of astronomers lobbying for the setting up of the new Royal Observatory in Paris.11

In the course of some passing remarks on telescopes in the preface to Micrographia, Hooke had been drawn into an aside on the need for readily available, high-quality lenses. The way of meeting this need, he went on, was to invent a ‘ready way’ (a machine) for making telescope object glasses. And he announced that he was in the process of refining such an ‘engine’, ‘by means of which, any Glasses, of what length soever, may be speedily made’.12

In an elaboration of these remarks, marked off from the main body of the text by its distinctive typography, Hooke sets down the technical details of his machine, illustrating his remarks with an engraving on the first plate of the volume alongside the well-known images of Reeves’s microscope and scotoscope.13

Auzout was a man on the make, eager to make a splash scientifically – in fact, he was trying hard to get himself made a member of the new French Académie des sciences (he succeeded in 1666, although he resigned from it in 1668). He read the preface to Micrographia in February 1665, and hurriedly inserted a critical response to it into a letter he had composed the previous year on the subject of the Italian Campani’s improved telescopes which he was preparing for publication.14 The expanded version of his ‘Letter to the Abbé Charles’ appeared in print in Paris in April or May 1665, and Auzout immediately sent a copy of the pamphlet to Oldenburg, with whom he was already in correspondence concerning Campani’s observations of the 1664 comet.15 Oldenburg produced a summary in English, including the criticisms of Hooke at length, and passed it to Hooke. Hooke responded with a letter to Oldenburg rebutting all Auzout’s criticisms, and this letter – preceded by Oldenburg’s English summary of Auzout’s published letter – was published in the Philosophical Transactions of the Royal Society of 5 June 1665 as ‘Mr Hooke’s Answer to Monsieur Auzout’s Considerations, in a Letter to the Publisher of these Transactions’.16

So now Hooke had a scientific ‘quarrel’ of a rather fashionable kind on his hands (intellectual quarrels in print were all the rage in London and Paris). The accusation which most exercised him at this stage was that he had not conducted proper trials of his lens-grinding machine, and that to have published an account of such an untried instrument, thereby claiming its priority, was unworthy of the Royal Society, given the Society’s commitment to experimental accuracy. As official Curator of Experiments, and having been admitted as a full Fellow of the Society only a year previously, Hooke was extremely anxious to clarify his position. He was quick to point out that there was a clear disclaimer placed prominently at the beginning of Micrographia, entirely dissociating the Royal Society from any ‘Conjectures and Quaeries’ of his own. Perhaps, he suggested, Auzout’s English had not been good enough to follow the text.17

As it turned out, Hooke’s suspicion was entirely correct. Auzout responded in a letter to Oldenburg of 22 June. He admitted that his English was indeed poor, and that, besides, he had only had Micrographia in his possession for two days. Inevitably he had not read it all, particularly since the illustrations were so captivating, and drew his attention away from the text.18

On 1 July Auzout wrote again, expressing the hope that this letter was with Oldenburg, and announcing his eager anticipation of meeting Wren, who was expected in Paris at any moment.19

Auzout’s public accusation of premature publication was unjust. There is firm evidence that Hooke had conducted proper trials of his machine and was continuing to do so. On 3 November 1664 Oldenburg told Boyle: ‘Mr Hooke is now making his new instrument for grinding Glasses, the successe whereof you will shortly heare of.’20 By the end of November Moray was giving detailed descriptions of Hooke’s machine and the trials being conducted with it to Christiaan Huygens. On 30 January 1665 (just before he dispatched Huygens’s copy of Micrographia) Moray told him that Hooke was being prevented from conducting further trials on his lens- grinding machine by his duties as Curator of Experiments to the Royal Society:21 ‘Mr Hooke has had so many matters on his plate these past days that he has not been able to carry through to completion his new invention for the lenses for telescopes.’22

By September Huygens was reporting to Auzout that there were problems with the operation of the ‘iron circle’ Hooke proposed using.23Again Moray admitted to Huygens that the demands the Royal Society was making on Hooke’s time were hampering his ability to complete projects undertaken:

We keep Mr Hooke so fully occupied with a thousand little things that he has not yet given me the description he promised me of his machine for measuring the refraction of light in water [a machine undertaken at the same time as the lens-grinding machine, and also announced and illustrated in Micrographia]. As soon as he does so I will forward it to you.24

The repeated claims that Hooke’s machine had never been tested were, as Hooke always insisted, entirely without foundation.

In fact, Auzout knew far more about Hooke’s lens-grinding machine than he was letting on in his letters to Oldenburg, even before the publication of Micrographia. Throughout the latter half of 1664 he had been receiving copies, at least in part, of the letters being exchanged about it between Huygens and Moray. The Anglo–Dutch connection had once again prepared the way, just as it had done in the case of the pendulum clocks. A vigorous correspondence in French between Moray and Huygens, who sometimes wrote to one another several times a week, ensured that whatever Hooke was doing in London, Huygens knew all about it within days. And whereas Moray was a scientific amateur, who enjoyed participating in events at the Royal Society but had little expertise in any specialism, Huygens was well able to pick up, adopt and adapt experimental details passed to him by Moray.

Huygens and Moray had begun corresponding about lens-making machines in summer 1664.25 Huygens reported to Moray Campani’s claim to have ‘a new way of making lenses using a lathe or turning device, and without using any kind of a mould’. Moray responded with the news that Hooke had shown such a machine to the Royal Society ‘five or six months earlier’, although it had yet to be demonstrated in action.26 Two months later he gave Huygens a much fuller account of the lens-grinding machine, presumably because by November he had had sight of the diagram and description given in Micrographia (licensed by the Society that month):

I think I told you earlier that a few months ago Mr Hooke proposed a sort of lathe for making the lenses for telescopes without using any form or mould. His invention is, to place the lens on the end of a rod which turns on two pivots, then to have a circle of iron attached to the end of another rod which turns in the same fashion, in such a way that the edge of the circle covers the centre of the lens, then applying pressure with the circle upon the lens so that the two rods make whatever angle is desired; according to how big or small the angle between the rods is, the surface of the lens has the section of a large or small sphere.27

In December Moray enlarged on this description in response to a further enquiry from Huygens. By now Hooke had built a prototype, which he had shown to the Royal Society:

Mr. Hooke’s machine is set up and I will keep you informed as to the success of this invention, and of all the details of its structure, if it warrants the effort of describing it to you. Concerning moulds or forms, he claims not to use any. But if it turns out to be necessary to use moulds to give initial shape, and then to polish them, as you suggest, on [an iron] circle, be assured that I will keep you informed. But it looks as if the circles will shape the lenses much more quickly than moulds could do, and so moulds are unnecessary, and as you told me, Campani does not use them at all.28

Huygens copied at least one of these letters to Auzout, keeping him up to date with the information Moray was supplying, in connection with Auzout’s interest in Campani’s machine.29 He also made a note to himself that the use of the iron circle was an exceptionally good idea, and one that he would consider incorporating into an equivalent machine himself, which in typical Huygens fashion he subsequently did.30 At the end of December he devoted a whole letter to Auzout to ‘explaining the iron circle for working lenses’.31 A minute for another letter to Auzout, written on 15 January 1665, shows that they were still discussing refinements to the circle.32 From his further correspondence with Moray it is clear that by now Huygens had built his own prototype machine, and was experimenting with Hooke’s ‘iron circle’.33

Here, as in the case of the balance-spring watch, we have Christiaan Huygens – eager for recognition in the new Paris Académie – absorbing technical detail gathered from informants in London, and incorporating it in his own scientific instruments without acknowledgement. This is precisely the period during which Hooke later accused Oldenburg and Moray of having leaked details of his balance-spring watch to Huygens, and Huygens of having adapted his own prototype watches accordingly.

Hooke was entirely unaware of this correspondence. He knew nothing of the swift transmission to Holland (and thence to Paris) of material he was presenting to the Royal Society in his official capacity as its recently appointed Curator of Experiments.34 In Moray’s eagerness to be seen by Huygens to be fully au fait with new scientific developments in England, he freely communicated construction details of Hooke’s lens-grinding machine, which an expert instrument-designer like Huygens could readily seize upon and adapt. So Moray was transmitting troubling levels of detail concerning a patentable machine, in whose development there was already significant European competition, to his friend Huygens, who in turn discussed technical details with Auzout.

Meanwhile, Oldenburg replied to Auzout’s letter of 22 June 1665 on 23 July, detailing Hooke’s further rebuttals of Auzout’s continuing refusal to accept the practicality of the lens-grinding machine. In view of Auzout’s lack of knowledge of English, and Hooke’s of French, Oldenburg offered himself as epistolary intermediary: ‘If you wish, I will be the go-between, since you do not know enough English to write to him nor he enough French to reply.’35

But all was not as it seemed. For by 15 July Hooke and the other curators had been instructed to move out of London, to Epsom, in the company of John Wilkins and William Petty, to continue Royal Society experiments safely away from risk of the plague.36Even if Oldenburg had shown Hooke Auzout’s second letter before he left, there is nothing to suggest that Hooke either drafted notes to it or wrote a full answer.37

Emergency measures were in place restricting the post during the plague epidemic. The most secure route for getting letters to Hooke was apparently via Wilkins. In September Moray told Oldenburg that he intended ‘to write within a day or two to Dr Wilkins, to put Mr Hook to the finishing his observations &c concerning the Cometes’.38 Two days later Moray advised Oldenburg: ‘I think you will do well to let Mr Hook know what [Huygens] sayes of Glasses [lenses] & what else concernes him by writing to Dr Wilkins.’39

At the end of September Hooke went to the Isle of Wight to attend to family business (his mother had died at the beginning of the summer), taking him even farther out of range of regular correspondence with Oldenburg in London. He remained there till the end of the year, occupying himself with geological investigations on and under the cliffs of Freshwater Bay. He returned briefly to London at the end of December, before once more returning to Epsom, finally rejoining the Royal Society circle in London in late February 1666.40

From July 1665 onwards, then, it appears that Hooke is being ventriloquised by Oldenburg in his absence in the Auzout–Hooke ‘controversy’.

On 13 August Auzout wrote once again to Oldenburg, again responding to Hooke point by point. Oldenburg’s translation of this letter into English survives. It is apparently intended for Hooke’s use, since it carries marginal annotations goading Hooke to respond to supposed ‘slights’ by Auzout in the text (which Oldenburg has made rather more provocative than the original): ‘What say you to this?’; ‘A handsome sting again will be necessary’; ‘Me thinks, here you may toss railleries with him’; ‘To this I say, He will needs make you say, what you say not’; ‘Non sequitur. You must rally with him again.’41 Perhaps Oldenburg hoped to have Hooke respond to Auzout himself when he returned to London. Perhaps he intended to act once more as intermediary, and to write another letter to Auzout, incorporating remarks of Hooke’s provoked by his own deliberately antagonistic annotations and prompts. Neither thing happened, because Auzout now acted pre-emptively. In July or August 1665 he republished his original ‘Letter to the Abbé Charles’, together with the entire correspondence to date between himself and Hooke (via Oldenburg) in French in Paris.

Oldenburg reacted indignantly, claiming he had never intended his last letter for publication. Auzout replied in some puzzlement – surely the correspondence had always been intended as part of a public epistolary controversy:

I am very upset that you are not happy that I have, at the request of my friends, published the letter that you were gracious enough to write to me to explain Mr Hooke’s feelings [concerning my continuing criticisms]. I did not consider this letter to be something belonging entirely to you, but rather as the reply of Mr Hooke, and because we had already both of us begun to print material on that topic, I saw no harm in supplying the rest, since our friends wanted so much to have sight of the continuation of the dispute.42

It seems clear from Oldenburg’s discomfiture that he had indeed himself composed the detailed arguments attributed to Hooke in the letter to Auzout of 23 July. He now found himself embarrassed by their being made public, which risked bringing the fact to Hooke’s attention. Fortunately, as we know, Hooke’s French was limited. In what was probably an act of damage limitation, Oldenburg summarised the arguments of Auzout’s new book in English, abbreviating and omitting parts Hooke might have construed as betrayals of trust, and published his synopsis in Philosophical Transactions.

Meanwhile Moray, Huygens and Auzout were corresponding vigorously about the affair, savouring every contentious sentence in the exchanges, often passing each other’s letters on as enclosures, and including copies of the Journal des sçavans and Philosophical Transactions where appropriate. In early June 1665, Auzout told Huygens that he was eagerly awaiting the arrival of Philosophical Transactions, which he gathered would contain the first instalment of his exchanges with Hooke:

I am told from England that Mr Hooke has taken up my objections against his machine in the first book of Philosophical Transactions which I hope will arrive on Sunday. We shall see what he says.

On 23 July Moray added a postscript to a letter to Oldenburg, written from Hampton Court, whence he was about to accompany the King to Salisbury:

I had almost forgot to desire you to send to Mr Hugens either the whole former Transaction [June issue], or so much of it as containes Hooks answer to Auzout & withall to let him know what Hook is doing as to his glasses [lenses and telescopes]. I have told him I would give you that task. L. Brounker will let you have hugens’s letter.43

The exchanges amongst this group shaped received opinion concerning the possibility of machine manufacture of precision lenses, and has continued to be treated as the authoritative account of the episode by historians of science ever since.44 Yet, although Hooke played a starring role in these exchanges, this was an extended conversation in which he had no direct voice, and over which he could exercise no control.

And although Hooke’s close friend Christopher Wren was in Paris throughout this period, in daily contact with the Auzout circle, he apparently did nothing to clarify the nature of Hooke’s machine, nor did he communicate the fact that Hooke was now absent from Royal Society circles. Wren was certainly consulted over the Auzout/Hooke affair. In April 1666 Auzout reported to Oldenburg that he had spoken to Wren shortly before he returned to England, concerning Hooke’s proposed method for increasing the focal length of lenses by filling the space between two lenses with liquid (a topic associated with the lens-grinding machine debate).45

By the end of July the Royal Society members had almost all dispersed because of the plague. Hooke, Wilkins and Petty were at Epsom, together with a substantial amount of experimental equipment, and assistant operators. Boyle was briefly with them, then retired to Oxford. Moray was with the King, first at Hampton Court, then at Oxford. For much of the period we are looking at Brouncker was on a ship off Greenwich seeing to navy business. Oldenburg stayed in London with his family, in a state of considerable agitation about the possibility of his succumbing to the plague (he made a will carefully separating his personal affairs from those of the Royal Society). During this time the Royal Society had two locations: a correspondence address with Oldenburg in London; and a transferred ‘real’ centre of operations in Oxford, where Moray and Boyle had established weekly meetings of a caucus of members.46 Huygens was in The Hague throughout, corresponding with Oldenburg, Moray and Auzout (his father, however, was in Paris for three months in early 1665).47

Wren visited Paris on behalf of Charles II, to inspect new building projects in train there, on 28 July 1665. We know he was frequently in the company of Auzout.48 From then on he provided a direct epistolary route for information from Auzout and his circle in Paris to both Oldenburg and Boyle.49

So we have an epistolary circuit of transmission, detailed explication, claim, counter-claim, assertion, surmise and response, which by mid-1665 has effectively developed a life of its own. The participating correspondents and the readers of the published versions are actually aware of only a small part of the network of exchanges which constitute the ‘controversy’, and the complex webs of influence these create.

Auzout and Oldenburg’s investment in all of this is pretty clear. From the Journal des sçavans in Paris and Philosophical Transactions in London was emerging an entirely new form of intellectual debate, one which reached beyond the bounds of coterie and nation into what was apparently a genuine Republic of Scientific Letters. Both Auzout and Oldenburg had a stake in establishing such an intellectual organ to enhance their own reputations, and both were remarkably successful at doing so. Hooke was more or less caught in the crossfire. As a result of Oldenburg’s letter-writing, translating and publications he acquired a reputation for making boastful claims he could not sustain. Controversy also became associated with his name on the Continent, at just the moment when Micrographia was establishing him as a formidable scientific presence.

The story of the simultaneous attempts in London, Paris and The Hague to develop a machine-method for manufacturing optical lenses is a minor one for the history of science. But we should note that this correspondence, circulating vigorously in Hooke’s absence, and without his knowledge, contains the ‘insider’ remarks supplying clues to the construction of his balance-spring watch which were later to cause him such personal grief and anger.

Indeed, the first ‘leaked’ information concerning the use of a coiled spring to regulate a pocket watch comes in a letter from Moray to Huygens which forms part of the lens-grinding exchanges, sent shortly after Hooke had left London. Hooke, Moray explains, has not yet been able to complete the collating of data on the 1664 comet, collected by virtuosi across Europe, which Huygens has asked for.50 As if to distract his somewhat demanding friend from the fact that he is unable to supply information on this topic, Moray changes the subject:

Up to now I have not ever spoken to you about another thing that he has suggested in his lectures on mechanics (which he gives every Wednesday outside the University term).51 It is an entirely new invention […]52

And Moray proceeds to explain how Hooke uses a spring (’un ressort’) as the regulator for his new watch. Like the ‘iron circle’ Huygens seized on for his lens-grinding equipment, this was quite enough to set Huygens off on the right track – particularly since, as in that case too, Moray proceeded to describe the balance-spring watch to Huygens in increasing detail in succeeding letters.

Hooke and Auzout, by the way, remained on cordial terms during this sequence of events and orchestrated controversies, despite Oldenburg’s promptings to the contrary. Throughout the exchanges, Auzout continued to refer to Hooke in the most respectful of terms, and Oldenburg consistently deleted these from his racy English translations. On 18 December 1666, for instance, writing to Oldenburg to communicate an important astronomical observation, Auzout wrote: ‘I think that Mr Hook, whom I salute wholeheartedly, as well as Mr Wren, will be very interested.’ Oldenburg omitted the phrase ‘whom I salute wholeheartedly’ from the version he published in Philosophical Transactions.53

By contrast with Oldenburg’s tendency to edit the two protagonists’ pronouncements, so as to present Hooke’s work as controversial and his relationship with Auzout as abrasive, the issue of the Journal des sçavans published on 20 December 1666 contained a review of Micrographia, praising it unreservedly and at length, in extravagant terms. Uniquely for the Journal up to that point, the review reproduces two reduced-size versions of the ‘cuts’ or plates for which it expresses enormous admiration (the louse and blue mould).54

The controversy conducted in the pages of the Philosophical Transactions and the Journal des sçavans, and in Auzout’s pamphlet publications issued in the course of 1665, achieved what Auzout wanted: to bring his astronomical expertise to the attention of Colbert and the King of France and secure himself a royal appointment. His opportunism is clear, and is supported by the fact that within two years he had quarrelled with other members of the Paris Académie and left France for Italy.

Oldenburg was more than content that the Philosophical Transactions should have become essential reading among virtuosi across Europe as soon as he began publishing them – by the fourth issue, the one containing the first adversarial exchange of letters between Auzout and Hooke, there was an absolute scramble to get hold of copies immediately they appeared. The élite, high-minded virtuosi Moray and Huygens cemented their intimate Anglo–Dutch friendship by exchanging sought-after information, and keeping each other ‘in the know’.

In spite of his forebodings, after his breakdown of 1676 Christiaan Huygens did return to the Académie des sciences in Paris for a brief period in late 1678. In spring 1681, however, he collapsed again. This time it was his sister Susanna, accompanied by her husband and their three children, who was sent to rescue him. She stayed three weeks – finally realising her dream of visiting the French capital – then brought Christiaan home for the last time. In 1684 the Académie, tired of his absence, dismissed him. He joined his father in the big family house in The Hague, keeping the aged Sir Constantijn company until his death in 1687.

Thereafter, Christiaan retired to his father’s estate, with its wonderfully serene and restorative garden, at Hofwijk. But with the Dutch invasion of England, his reputation as a brilliant scientific innovator enjoyed one final flowering abroad. For while Hooke was an old-style divine-right-of-kings man (like his close friend Sir Christopher Wren), and had, right up to William of Orange’s arrival, steadfastly backed James II as England’s legitimate monarch, Christiaan Huygens, his scientific adversary, was the clever younger brother of William’s private secretary, Constantijn Huygens junior, who had played a prominent role in the successful invasion.

In London, Constantijn junior was now a senior figure in the new administration, with real political power. The fact that all Sir Constantijn Huygens’s children spoke excellent English was now a further distinct asset. The young English scholar Thomas Molyneux, visiting Christiaan during his final period in Paris, reported that he had received a warm welcome: ‘When he understood after a few words that I was English, he spoke to me in my own language, beyond all expectation, and moreover, extremely well.’55

Constantijn’s new position in England tempted his brother Christiaan out of retirement, with the prospect that he could now be assured of real respect from the English virtuosi, and could finally take his place among the Fellows of the Royal Society (he had been elected an overseas member in 1663 – the first foreigner to receive that honour).

Christiaan had a further reason for allowing himself to be tempted away from the seclusion of Hofwijk. For two years he had been poring over Isaac Newton’s Philosophiae Naturalis Principia Mathematica, or the Principia, of which the author had sent him a presentation copy, working painstakingly through its mathematical calculations. Shortly after he read it, Huygens told Constantijn that he had enormous admiration for ‘the beautiful discoveries that I find in the work he sent me’.56 When John Locke came to visit him, and asked him if he thought Newton’s mathematics, which he admitted he could not himself follow, were sound, Christiaan told him emphatically that they were certainly to be trusted. Newton, to whom Locke recounted this, proudly repeated the Dutch mathematician’s endorsement in London. A visit to London would enable Huygens to meet Newton face to face.

In preparation for his trip, Christiaan resuscitated and rewrote his ten- year-old treatise Traité de la lumière (Treatise on Light), to provide him with his credentials for re-entering English intellectual life. He wrote to Constantijn:

I had intended to stay here at Hofwijk for the whole winter … However, you might have an opportunity to see Mr. Boyle. I would like to visit Oxford, if only to make the acquaintance of Mr. Newton [in fact, of course, Newton was at Cambridge] for whose excellent discoveries I have the greatest admiration, having read of them in the work [Principia] which he sent me.57

Christiaan arrived in London on 6 June 1689. He joined Constantijn junior and Constantijn junior’s son in lodgings close to Whitehall. A week later the three of them went together to stay at Hampton Court Palace, where the new King and Queen were in residence. On 12 June Christiaan travelled by boat back along the Thames to London for a meeting of the Royal Society. He recorded in his diary:

Meeting at Gresham College in a small room, a small cabinet of curiosities, over-full but well kept. Hoskins President, Henshaw Vice-President, Halley Secretary. Van Leeuwenhoek’s letter was read. Newton and Fatio were there too.58

In the period of uncertainty leading up to the Dutch invasion and William’s claiming the English throne, Isaac Newton had already begun to emerge from his sheltered position as a solitary scholar at Trinity College, Cambridge. In 1687, when James II’s interference with the university roused even those as aloof as Newton from their political indifference, he found himself nominated to act for the university in what turned out to be a critical piece of resistance to James II’s policy of installing Catholic cronies in key administrative positions. Newton was one of nine prominent members of Cambridge University who in April 1687 – at the very moment when Edmond Halley was seeing the Principia through the press – confronted the notorious ‘Hanging Judge’ Lord Jeffreys, and refused to allow James II to appoint his personal nominees, without qualification or oath, to senior academic positions.59

So at the beginning of 1689, Isaac Newton was already one of the most prominent, Protestant-supporting members of the university community, with impeccable credentials to serve the incoming regime. On 15 January he was elected one of the three university representatives to the national Convention appointed to settle the legitimacy of William and Mary’s claim to the English throne.60

Two weeks after his arrival in London, having returned to Hampton Court, Christiaan Huygens had an audience with King William and dined with his Dutch favourite, William Bentinck, Earl of Portland, the most powerful man at court. It had been suggested beforehand that, as an esteemed virtuoso particularly well-connected with the Dutch royal household, Christiaan might put a word in with William III on Isaac Newton’s behalf, putting the mathematician’s name forward for a senior academic promotion. Two days later, on 10 July, Christiaan, Nicolas Fatio de Duillier and Newton met at seven in the morning in London, ‘with the purpose of recommending Newton to the King for the vacant Mastership of a Cambridge College’.61 On 28 July, Christiaan attended a fashionable concert at which he was introduced to the Duke of Somerset, Chancellor of the University of Cambridge, and Newton’s preferment was once more discussed.62

So Christiaan Huygens was directly involved in the political game of snakes and ladders, in which Newton – hitherto a small player, politically – moved centre-stage, while formerly powerful intellectuals like Wren and Boyle were nudged to the margins.

The Cambridge college whose headship Newton had ambitions to fill was King’s, and John Hampden, the court lobbyist on Newton’s behalf who approached Huygens, was a leading Parliamentary player. Huygens’s approach evidently had the desired effect. Shortly thereafter, William wrote to the Fellows of King’s College, informing them of his desire that they appoint Newton as their new Provost. The new foreign King was, however, roundly rebuffed by the Fellows, who selected another candidate. This was probably just as well for Newton’s future career as a public figure, since imposed royal appointments were deeply unpopular.63

Even though this personal intervention of Huygens’s to advance Newton’s career did not succeed, the scientific relationship between the two men was thereby significantly strengthened. In August, before he left for home, Huygens received two papers from Newton on motion through a resisting medium. At some point during the visit they also had lengthy discussions of optics and colour.64 Huygens told the German mathematician Leibniz that Newton had communicated ‘some very beautiful experiments’ to him – probably his experiments with thin films similar to the ones Huygens himself had performed twenty years earlier, and to those Hooke had recorded in his Micrographia even earlier.65

After Christiaan Huygens had returned to The Hague, at the end of August 1690, Nicolas Fatio de Duillier spent a month with Newton in London, followed by fifteen months in the Netherlands, mostly with Huygens.66 Over the next several years, Fatio facilitated the exchange of ideas between the two men. Huygens came to regard Fatio as his direct link through which he learned Newton’s latest thoughts on mathematics, gravity and light.

Although Christiaan Huygens retreated rapidly to his self-imposed life as an intellectual invalid at Hofwijk, his brother Constantijn continued to be a person of influence at the court of William and Mary.67 Newton, mean-while, became Master of the Royal Mint, and a formidable figure in London political circles. He was also by now an international celebrity as the author of the Principia – the man who had finally unlocked the secret of the motion of the heavens. In terms of his own continuing career, Hooke now found himself between a rock and a hard place: between the City and the Royal Society. In neither did he any longer command any kind of authority, and in neither could he find powerful protectors who had survived the change of dynasty.68

So when, on 12 June 1689, Huygens, Newton and Hooke found themselves together at a meeting of the Royal Society, Newton and Huygens were, unbeknown to Hooke, about to embark on a new, yet more intense phase of their intellectual relationship. Hooke, meanwhile, was increasingly ill at ease with the Royal Society, where all but a few of his oldest friends among the members seemed to take him less and less seriously.69

Of all Hooke’s claims to scientific breakthrough, and to have anticipated Huygens’s and Newton’s ideas, those in optics were probably the most convincing and well-documented. Both Newton and Huygens had started their work on thin coloured films in 1665–66 after having read Hooke’s suggestive discussion in Micrographia.70 Similarly, both men had pursued the wave theory of light proposed in that book, and the associated calculation of the velocity of propagation of light. In the early 1670s, when Newton first wrote to the Royal Society with his theory of colour, and first crossed swords with Hooke, who inevitably challenged him, Newton was open about having been influenced by Hooke’s work.71 By 1675, however, egged on by Oldenburg, Newton was denying Hooke’s influence and claming that any ideas the two men shared were simply ‘common thoughts’: ‘I desire Mr Hooke to shew me therefore … [that] any part of [my hypothesis] is taken out of his Micrographia.’72 Nevertheless, Hooke’s experiments in optics were an authoritative contribution to the reputation of the Royal Society, and some important intervention from him at that auspicious meeting of the Society in which Huygens and Newton participated was to be expected. None is recorded.

Following the meeting of the Royal Society on 12 June, Hooke worked through the arguments propounded in Huygens’s Treatise on Light with even more than his usual punctiliousness. We can surmise that he was discouraged and depressed by the confident authority with which Huygens and Newton had conducted themselves at the Royal Society meeting. He responded by drafting two lectures defending in detail his own ‘philosophical’ views: the first dealing with those concerning light and its properties (wave theory and thin films), the second dealing with planetary motion (orbits of the planets, and shape of the earth). Hooke’s health that year was particularly bad. According to Richard Waller, he was ‘often troubl’d with Head-achs, Giddiness and Fainting, and with a general decay all over, which hinder’d his Philosophical Studies’.73

Eight months later, on 19 and 26 February 1690, Hooke delivered his response to the Society.74 The first lecture includes a particularly poignant restatement of his own originality, which appeals to his listeners to assess his own contribution before deciding that Huygens’s competing views are correct:

This is in brief what I thought necessary to be considered before what I have formerly Deliverd concerning Light be rejected and before what is here Deliverd be Received, for though I doe readily assent that Monsieur Huygens & others much more Able than myself may penetrate farther into the true causes of the Phenomena of Light than I had done at that time; yet I confesse I have not yet found any phenomenon or hypothesis propounded by any writer since that time that has given me cause to alter my sentiments concerning it. However I should be very gladd to meet with any such and shall be as Ready to Relinquish this Upon the meeting with a better as I was in making choice of it for the best at the time of publication.75

In the second lecture, Hooke went on to analyse Huygens’s Discours sur la cause de la pesanteur (Discourse concerning the cause of weight). Here Hooke fastens onto Huygens’s treatment of gravity:

For what follows afterwards is additionall to that Discourse as he himself Declares in his preface, which is concerning those proprietys of Gravity which I myself first Discovered and shewed to this Society many years since, which of late Mr. Newton has done me the favour to print and Publish as his own Inventions. And Particularly that of the Ovall figure of the earth was read by me to this Society about 27 years since upon the occasion of the Carrying the Pendulum Clocks to Sea And at two other times since, though I have had the Ill fortune not to be heard, and I conceive there are some present that may never well Remember and Doe [not] know that Mr. Newton did not send up that addition to his book till some weeks after I had read & shewn the experiments & Demonstration thereof in this place.76

As usual, Hooke insists that he had himself long ago made every one of the discoveries Huygens and Newton claim for themselves. This time he had clear justification for maintaining his influence, and documented the indebtednesses with measured intelligence. A group of well-disposed members attended the lectures in question, including Sir Robert Southwell, Sir John Hoskins, Waller, Edmond Halley, John Wallis, Hans Sloane ‘and divers others’.77 But Huygens and Newton had moved on.78 According to the records, Hooke’s intervention was barely registered, and nobody bothered to respond.79

The mercurial Dutch virtuoso Christiaan Huygens floats in and out of other people’s stories from his adolescence, through the Europe-wide acclaim accorded him in his prime (while he resided in Paris, as Louis XIV’s favourite scientist), down to his decline, depression and death. From his childhood he had been his influential and ambitious father’s favourite. Sir Constantijn was determined to find his second son a lucrative appointment to enable him to utilise his scientific talents, and as an anglophile his first preference would have been for Christiaan to join the scientific community in London. Between October 1661 and April 1665, Sir Constantijn shuttled between Paris and London as he negotiated the return of Orange (seized by Louis XIV) to the house of Orange. While he was at it, he lobbied people in high places to try to secure a position for his son.80

Christiaan preferred Paris. Even the festivities surrounding Charles II’s coronation did not make London seem glamorous to him. After his first visit, he wrote to his brother Lodewijk:

I had little pleasure of my visit to London … The stink of the smoke is unbearable and most unhealthy, the city poorly built, with narrow streets having no proper paving and nothing but hovels … There is little going on and nothing compared with what you see in Paris.81

In December 1666, Christiaan Huygens was appointed to a salaried position in the new Académie royale des sciences in Paris, though he was made a foreign Fellow of the Royal Society, and remained in active contact with his fellow scientists in London throughout his life.

If it is hard to imagine a biography of Christiaan’s father Sir Constantijn which does not straddle the Narrow Sea and consider him in a robustly Anglo–Dutch historical context, the same is even more true of Christiaan, whose life and career as represented in the literature of the history of science are both shadowy and contradictory – depending on whether he is being looked at in a Dutch, English or French context and milieu.

The events described in this and the preceding chapter have made it clear, I hope, that Christiaan Huygens’s claims to priority in the matter of the spring-regulated pocket watch, and pre-eminence in the field of lens- grinding, microscopy and telescopy, are inseparable from his sometimes uncannily close connections with his British and French counterparts. So let it be another of Christiaan Huygens’s involuntary international collaborations at a distance that takes us forward to the final chapter of this story – Anglo–Dutch relations in the New World.

In a letter written on 25 October 1660 from Hartford, Connecticut, where he was governor of the English colony, John Winthrop junior, son of the founder of the English colony at Jamestown, and a considerable scientist in his own right, told the English scientist and educator Samuel Hartlib that he was disappointed that his ‘Telescope of [focal length] about 10 foot doth shew little of Saturne’.82 He asked Hartlib, who acted as an intellectual go-between for scientists and practitioners across Europe, to tell him if he knew ‘the manner of the fabrique of that new Telescopium in holland’, expressing the hope that Christiaan Huygens might have described such an instrument accurately in his Systema Saturnium (System of Saturn), which Winthrop had not yet read. Huygens’s book, announcing his remarkable discovery of Saturn’s rings, had been published the previous year. Winthrop’s anticipation of a copy arriving in Connecticut is further evidence of the ease with which new publications circulated across the known world. It was another year, however, before Hartlib wrote telling Winthrop that ‘some weeks agoe’ he had sent him ‘the Systeme of Saturne with all the Cuts [illustrations]’. Winthrop was gripped by the contents of Huygens’s book, and was keen to observe the phases in Saturn’s appearance himself.

His astronomical observations were interrupted by more pressing local political concerns. Connecticut had been founded during the Protectorate of Oliver Cromwell. Now, in 1661, Winthrop was obliged to return to England to negotiate a new charter for the colony with the returning King, Charles II. He was away for almost two years, during which time he was successful in gaining for the inhabitants of Connecticut a charter from the King, assigning them lands from the Pawcatuck River all the way westwards to the Pacific Ocean. While in England he was also made a Fellow of the Royal Society. He returned to Connecticut in 1663, and in 1664 assisted in Charles II’s seizure of the thriving Dutch settlement on Manhattan Island for the English.83

In January 1665, in the midst of unfolding events following the seizure of Manhattan, Winthrop wrote to Sir Robert Moray at the Royal Society, sending him observations of the moons of Jupiter which he had made with a refracting telescope of ’3 foote and [a] halfe with a concave ey-glasse’. Inspired by Christiaan Huygens’s book, he had, it seems, brought the English-made telescope back with him from London:

Having looked upon Jupiter with a Telescope upon 6th of August last I saw 5 Satellites very distinctly about that planet; I observed it with the best curiosity I could, taking very distinct notice of the number of them, by severall aspects with some convenient time of intermission; and though I was not without some consideration whether that fifthe might not be some fixed star with which Jupiter might at that time be in near conjunction, yet that consideration made me the more carefully to take notice whether I could discern any such difference of one of them from the other four that might by the more twinkling light of it or any other appearance give ground to believe that it might be a fixt star, but I could discern nothing of that nature.84

Winthrop turned out to be mistaken – although a fifth moon of Jupiter was indeed discovered in the nineteenth century, his telescope could not have detected it, and he is indeed most likely to have taken a fixed star, crossing the face of Jupiter, for a satellite circling the planet.

But the accuracy or otherwise of John Winthrop’s observations of Jupiter is not our concern here. What is, is that more than three thousand miles from London, in an American colony, an English astronomical enthusiast’s passion for telescopic observation had been kindled by a young Dutch astronomer who had made an exciting discovery about the planet Saturn. In 1671, Winthrop presented his reflecting telescope as a gift to the new Harvard University – its first recorded astronomical instrument. So the emerging science of astronomy in North America, with a long and distinguished future stretching ahead of it, was, it seems, in its earliest days equally indebted to English and Dutch astronomers back home.

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