De Zeventiende Eeuw. Jaargang 12

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Huygens and the Royal Society
Mordechai Feingold

Anyone seeking to evaluate Christiaan Huygens' relations with the Royal Society or, more generally, with English savants, would undoubtedly find it irresistible to take his or her cue from the famous 1670 ‘death-bed’ scene described by Francis Vernon. Believing he was about to die, Huygens entrusted Vernon with ‘12 propositions wich concerne the Doctrine of motion wth their demonstrations’, as well as sundry other papers for safe delivery to the Royal Society. Then, Vernon's narrative continues, Huygens

‘fell into a discourse concerning the Royal Society in England wch hee said was an assembly of the Choisest Witts in Christendome & of the finest Parts: hee said hee chose rather to depositt those little labours of his wch god had blesst & those pledges wch to him were dearest of any thing in this world, in their hands sooner then in any else. Sooner then of those into whose Society hee was here incorporated & from whom hee had received all demonstrations of most affectionate civilitie. because he judged the Seat of Science to bee fixed there & that the members of it did embrace & promote Philosophy not for interest, not through ambition or a vanity of excelling others, not through fancy or a variable curiosity, butt out of naturall principles of generosity & inclination to Learning & a sincere Respect & Love for the truth, wch made him Judge that their Constitution would bee therefore more durable because their designes & aimes were soe honourable & that God almighty would give a great stability & blessing to their Labours because hee had inspired them with soe Worthy desires. Whereas hee said hee did forsee the dissolution of this academie because it was mixt wth tinctures of Envy because it was supported upon suppositions of profitt because it wholly depended upon the humour of a Prince & the favour of a minister, either of wch coming toe relent in their Passions the whole frame & Project of their assembly cometh to Perdition.’

Having singled out several members of the Society for particular praise, Huygens concluded by commending ‘the whole Society in generall for a most chearfull & unanimous agreement & harmony in the advancing of knowledge wthout wch hee said it was impossible for the most selected body or the most chosen witts long to subsist.’^1.

Notwithstanding the temptation to interpret this extraordinary outburst of emotion as indicative of Huygens' true sentiments toward English science and its practitioners, the actual state of affairs was far more complicated. Huygens' veneration of the English was not unqualified. Nor did he unequivocally hold the Royal Society in greater esteem than he did the Académie Royale des Sciences, to whose foundation and working he contributed so much. It seems to me that previous scholars have not been fully cognizant of the numerous occasions in which Huygens clashed with members of the Society. And even when isolated episodes have been cited, their significance has been downplayed. On the whole the rela-

1. The Correspondence of Henry Oldenburg, eds. A.R. Hall and M.B. Hall, 13 vols. (Madison, Wisc. and London, 1965-1986), vol. 6, pp. 502-506.

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tionship has been portrayed as friendly, productive, and long lasting. As Rupert Hall put it

‘Huygens was a constant participant in English scientific life. He was esteemed in this country for his discoveries, for his intelligence and empirical skills, and for the fairness of his judgment. Unlike Newton, Huygens was a man without enemies. Though he found the English difficult in social relations, and excessively insular in their intellectual pride, he charmed everyone except Robert Hooke. (...) We have no reason to suppose that Vernon's account of these events was materially in error, and I think we may take it as giving a faithful picture of Huygens' opinion of his English colleagues.’^2.

My purpose in this paper is to offer a fuller and more nuanced reading of the relationship between Huygens and the members of the Royal Society. Not that I wish to deny the existence of a fruitful and stimulating exchange of ideas between the two sides; only to emphasize the intense nature of the relationship and point out the deep-seated ambivalence that colored the perceptions and dealings of both Huygens and the English savants. In fact, I would like to suggest that perpetual controversy was the hallmark of this relationship and, indeed, that tension and rivalry were conspicuous from the outset. In the domain of science such factiousness was not necessarily a drawback; indeed at times it could, and did, spur the participants into profitable activity. Henry Oldenburg, for one, often utilized precisely such a method in goading his correspondents to reflect on the work of others. However, in this particular instance the intensity of the relationship, the strong personalities of the individuals involved, together with the accumulative effect of recurring clashes over priorities, took its toll - ultimately producing an irreversible rupture.

It is generally assumed that Huygens was elected Fellow of the Royal Society on 22 June 1663, during his second visit to England. However, some evidence suggests that he may have been affiliated with the Society, at least as a supernumerary member, already during his first visit in 1661, when the procedures for election (especially of foreigners) had not yet been instituted.^3. John Evelyn recorded in his diary for 1 April 1661 that he ‘din'd with that greate Mathematicia[n] & virtuoso Monsieur Zulichem, Inventor of the Pendule Clock and Phaenomenon of Saturns anulus; he was also elected into our Society.’ If Huygens was admitted member of the Royal Society at that time - and the minutes for that day do not mention him - he was simply reelected in 1663, as were several English members.^4. Be this as it may, it is evident that during his first visit Huygens had established close ties with several Fellows, especially Sir Robert Moray, and that such amity conferred on him a preferential treatment that lasted for several years. In fact, Huygens was conspicuously exempted from the restrictions imposed by the Society from the start on the communication of its procedures to non-members. Enshrined in the Society's 1663 statutes, the policy of confidentiality was explicit: ‘No Fellow shall give any copy or transcript of any matter contained in the Register-books, or other Books of the Society, to any one that is not a Member thereof; nor communicate the same to any such person to be transcribed, without particular leave obtained at a Meeting of the Society; except the said matter were originally brought in, or communicated by himself.’^5. Clearly then, even if he was not officially elected a Fellow of the Society, Huygens' expressed wish following his return to Holland to

2. A.R. Hall, ‘Huygens and Newton’. In: The Anglo-Dutch Contribution to the Civilization of Early Modern Society (London, 1976), pp. 55, 57.

3. In a letter of 13 December 1660 to Adam Boreel Oldenburg noted the ambivalence among the Society Fellows on whether to admit foreigners as members: ‘Whether Foreigners will be admitted I doubt very much, though some say so.’ Oldenburg, Correspondence (n. 1), vol. 1, p. 406.

4. The Diary of John Evelyn, ed. E.S. de Beer, 6 vols. (Oxford, 1955), vol. 3, p. 276. Interestingly, in 1663 the common procedures of election were disregarded and Huygens was admitted Fellow without being first proposed candidate. Th. Birch, The History of the Royal Society of London, 4 vols. (repr. Bruxelles, Culture et Civilisation, 1967), vol. 1 p. 263.

5. The Record of the Royal Society of London, 4th ed. (London, 1949), p. 300. The wording of the statute follows closely the wording of the Society's 13 March, 1661 resolution (Birch, History (n. 4), vol. 1, p. 18).

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be kept informed about the work carried on at Gresham College was discharged meticulously by Moray and others, and further attested to the Society's allowing Huygens pretty much the privileges of a member.

Both sides benefited from such intimacy. For the embryonic Royal Society Huygens was considered quite a ‘catch’, if only for propagandist reasons. His European stature conferred luster on the Society, and his participation in projects sponsored by the Society were advertised by Oldenburg to correspondents throughout Europe. Huygens himself participated in the publication of the aims of the Society and the value of its work. He contrasted the verbal and ‘sterile’ proceedings of the French academies with the ‘deeds’ of the young London Society, and such reports produced, at least temporally, an effort by the Montmort Academy to substitute experimentation for speculations and debates. Noticing such a metamorphosis, Oldenburg could not conceal his glee, boasting in a letter to Boyle that the Royal Society would soon ferment all of Europe.^6. Nor was Huygens less valuable as an active and productive collaborator because of the distance that separated them. The impressive speed with which letters travelled between London and The Hague (or Paris) made him at least as accessible as were most non-London members of the Society - and the density of the correspondence between Huygens and Moray before 1666 certainly attests to the former's active ‘participation’ in the Society's proceedings, either through contributing ‘matter’ to their discussions, or commenting on experiments and papers there discussed.

It is here that the benefit the Society derived from Huygens' membership most closely intersected with the advantages reaped by the latter. Both during, and subsequent to, his visits to England, Huygens was greatly stimulated by the work carried on at Gresham College. For example, having been infected with the vacuum fever in London in 1661, upon his return to Holland Huygens immediately began constructing his own airpump, and his experiments produced not only the initially embarrassing discovery of anomalous suspension - a topic that would engage both Huygens and other members of the Royal Society for years to come - but the first quantitative expression of Boyle's Law as well.^7. Similarly, Huygens' work on pendulums and motion, his astronomical works, and his practical work with telescopes, lenses, and clocks, was stimulated by the labors of the English savants and, in turn, received careful attention in London. Equally important, despite his being a pensionary of Louis XIV since 1664, before 1666 the Royal Society was the only scientific institution to which Huygens belonged and on which he relied to keep abreast of scientific news. Moreover, the Society served as a powerful resource of legitimizing his work and stature. Thus, the English verified his theory of Saturn and contributed to the process of validating the efficacy of his marine chronometers. More important still, Huygens even claimed that the Royal Society had confirmed his as yet unpublished laws of motion. ‘As for his treatise on motion,’ wrote Spinoza to Oldenburg in 1665,

‘I think it is vain to expect it. It is so long since he began to boast that he had discovered by calculation laws of motion and laws of nature quite different from those given by Descartes, and that those of Descartes are almost all false, yet so far he has given no example of this. I know indeed that about a year ago I heard from him that all his former discoveries concerning motion, based on calculation, had subsequently been verified by experiments in England, which I can hardly believe.’^8.

6. H. Brown, Scientific Organizations in Seventeenth Century France (1620-1680) (repr. New York, 1967), pp. 120-121; Oldenburg, Correspondence (n. 1), vol. 2, pp. 540-541.

7. A. Stroup, ‘Christiaan Huygens & the Development of the Air-Pump’. In: Janus 68 (1981), pp. 129-158.

8. Oldenburg, Correspondence (n. 1), vol. 2, pp. 540-541.

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Such intimate, and unparalleled, ties between Huygens and the members of the Royal Society notwithstanding, it is important to recognize the conspicuous recurrence of rivalry and dispute between them. Perhaps this was inevitable given the affinity between the research interests of Huygens and Society members which, under the best circumstances, could not but give rise to competition and jealousy. Initially such sparring was of the constructive kind. As Jean Chapelain wrote François Bernier on 9 November 1662, ‘Huygens is often in controversy with [members of the Royal Society], and from their discussions rise excellent truths which serve to advance this sort of study.’ Here Chapelain described, and condoned, the accepted early modern norm of scholarly and scientific discourse poignantly delineated by Pierre Bayle a few years later. In the ‘Commonwealth of Learning’, Bayle wrote, ‘an innocent War is engaged against any one whatever’ in the name of truth and reason, and ‘every particular Man has the Right of the Sword, and may exercise it without asking leave of those who govern.’^9.

The first occasion for conflict presented itself a few months after Huygens' first visit to England. On 4 September 1661, following the reading of Bernard Frénicle de Bessy's hypothesis concerning the motion of Saturn, Christopher Wren was requested to deliver to the Society his own ‘observations and hypothesis of Saturn’. Within a month Wren complied in the form of a letter to Sir Paul Neile, in which he modestly slighted the value of his hypothesis, especially now that ‘Hugenius hath outrid [him]’. Wren explained that he opted ‘rather to neglect that right [he] might in justice have vindicated, than by challenging it too late, incur the jealousy of being a plagiary’. Wren insisted that he consented to present his theory only because the Society would ‘not suffer [him] to continue in this peaceable humour’. Having recounted the course of his observations since 1655 and the formulation of his own theory, he confessed to having abandoned it after hearing about Huygens' hypothesis:

‘I was so fond of the neatness of it, and the natural simplicity of the contrivance agreeing so well with the physical cause of the heavenly bodies, that I loved the invention beyond my own; And though this be so much an equipollent with that of Hugenius, that I suppose future observations will never be able to determine which is the truest, yet I would not proceed with my design, nor expose so much as this sheet any farther than to the eye of my bosom friend.’

Wren's modesty and candid acknowledgement of the superiority of Huygens' theory were sufficient to prevent a dispute, even when Wren's explicit request that his hypothesis should not be sent to others or published was ignored, and copies forwarded to both Frénicle and Huygens.^10.

In contrast, the collaboration between Huygens and Alexander Bruce, second earl of Kincardine proved far less auspicious for the Royal Society (which inadvertently got dragged in). Huygens and Bruce began their collaboration on the marine chronometer in 1661, and while Huygens was unquestionably responsible for the design of the clock, it was the young Scottish nobleman who solved the problem of fitting it to keep time at sea. Unfortunately, Kincardine soon became convinced that he deserved at least an equal share in both profits and credit for the anticipated discovery of a reliable method to determine longitude at sea and, by 1663 he even applied for an English patent. Understandably, Huygens grew

9. Brown, Scientific Organizations (n. 6), p. 94; The Dictionary Historical and Critical of Mr Peter Bayle, 2nd ed. revised by Pierre Des Maizeaux (5 vols. London, 1735; repr. New York, 1984), vol. 2, p. 389, note D.

10. Birch, History (n. 4), vol. 1, pp. 47-49; O.C., vol. 3, pp. 416-427.

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disconcerted and his letters to Moray gave expression to his resentment of what he perceived to be Kincardine's attempt to rob him of his discovery. Moray was placed in the unenviable position of arbiter, and all he could do was to reproach both parties and, finally, to cajole them into agreeing to take out a patent in the name of the Royal Society. But nonetheless, though Huygens acquiesced to this arrangement, the outcome of the affair was detrimental to his relations with Moray, who failed to ‘defend’ Huygens, or so the latter believed.

The falling out between the two can be easily measured quantitatively. Between April and December 1661 some twenty-one letters were exchanged between Huygens and Moray. Thirty-five letters survive for the next two years, and forty-eight for the period between January 1664 to May 1665. Then the volume sharply decreases. Only five letters survive for the next seven months, and only three were exchanged during the first half of 1666, prior to the breaking-off of the correspondence in mid-May for almost two and a half years. This abrupt suspension of the epistolary exchange cannot be explained simply in terms of Moray's consigning the correspondence to Oldenburg when he prepared for his sojourn to Scotland, since Moray left a full year after the correspondence was suspended. Besides, it is significant that Huygens terminated all correspondence with England during that period.

Undoubtedly, this new attitude can be attributed, at least in part, to Huygens' resentment of the lukewarm support he had received from Moray and the Royal Society during his protracted dispute with Kincardine. But more important was his move to Paris. Huygens kept his English friends in the dark about the exact nature of his negotiations, so much so that in September 1665 Moray turned to Oldenburg for information concerning Louis XIV's invitation of the Dutchman to Paris, explaining in a subsequent letter: ‘I say nothing to Mr Hugens of his going to France because he sayes nothing of it to me’. Whether Huygens was simply cautious - even Auzout wrote Oldenburg on 2 February 1666 that ‘It is so long since Mr. Huygens wrote to anyone in this country’ - or whether his silence reflects the chilly aftermath of the disputes over his clocks is not clear. It is striking, though, that the last English letter to reach Huygens before the protracted silence was a 1etter from Oldenburg, who congratulated Huygens on his safe arrival to Paris, expressing the hope that a new era of cooperation between the two societies would be inaugurated.^11. Huygens must have seen matters differently. Having broken out of his relative isolation in Holland, and having obtained a very lucrative position in Paris, it seems he had little need for his cantankerous English corespondents. Only in late September 1668 did Moray attempt to renew the correspondence, but his conciliatory effort miscarried miserably as a consequence of the Gregory affair.

It was Moray who introduced James Gregory to Huygens early in 1663, urging the latter to pursue and evaluate Gregory's Optica promota. As things turned out, Gregory missed Huygens in Paris and the letter in which Huygens conveyed to Moray his opinion of the book does not survive. In September 1667 Gregory sent Huygens a copy of his new book, Vera circuli et hyperbolae quadratura, reminding him of his previous attempt to establish contact and requesting his opinion of the book. Gregory's rather civil letter went unanswered, but on 2 July 1668 Huygens published a scathing review of the book in the Journal des Sçavans where, in addition to controverting certain of Gregory's assertions, he also claimed for himself the priority

11. 11. Oldenburg, Correspondence (n. 1), vol. 2, pp. 504, 540; vol. 3, pp. 37, 129-130.

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to some of Gregory's results. Stunned, Gregory immediately retaliated with an indignant rebuttal in the July issue of the Philosophical Transactions and, following a rejoinder by Huygens in the Journal des Sçavans, the Scot struck back with an abusive preface to his Exercitationes geometricae.^12. Initially, Gregory was backed not only by John Collins but also Brouncker and Wallis, whose favorable opinion was published by Oldenburg in the March 1668 issue of the Philosophical Transactions. As late as August 1668 Wallis was still of the opinion that though he did not agree with everything in the book, he was ‘well innough satisfied with it’ and, furthermore, expressed his surprise that Huygens ‘should write against him unprovoked, unlesse there had been more cause than what’ he could see. Wallis conveyed such approving sentiments to Huygens as well.^13. Unfortunately, by then Gregory was not receptive to any criticism and his blunt response to Wallis' alienated the touchy Oxford professor, who henceforward squarely championed Huygens' case against the increasingly acrimonious writings of Gregory.^14.

Huygens apparently expected the Royal Society to follow Wallis' lead and support him, and he undoubtedly interpreted Oldenburg's surprising solicitation in October 1668 for his rules of motion as indicative of the Society's favorable disposition toward him. He was not completely wrong. Always deferring to Wallis in mathematical matters, Oldenburg bolstered Huygens' cause, at least covertly, thereby irrevocably alienating Gregory who subsequently refused to contribute to the Society's work. As he explained to Collins in 1670, ‘I am not yet so much a Christian as to help those who hurt me.’ Brouncker, it appears, continued to be partial to Huygens' case and, notwithstanding the pressure exerted by Collins, refused for several months to allow the publication of further rebuttal by Gregory in the Philosophical Transactions. Above all, Huygens expected Sir Robert Moray to stand firmly by him and ‘as far as possible ... vindicate [him] against the false aspersions cast upon [him] by Mr. Gregory’. But in this he was deeply disappointed. Though he wrote Huygens in late September 1668 that he would like to renew their ‘ancient correspondence’, Moray not only failed to exhibit the intimacy that marked his former letters, but he also proceeded to reproach Huygens for the bitterness of the dispute - although, he assured Huygens, he was as disapproving with Gregory.^15.

Most important, Moray allowed Collins to guide him in appraising the substance of the controversy and proportionate culpability of the two adversaries, and it was the position paper drafted by Collins (rather than the one prepared by Wallis) which was ultimately dispatched to Huygens as denotative of the Society's judgment of the case.^16. Understandably, Huygens was offended by it. After all, Collins himself had intimated to Gregory that his ‘designe in it being partly to show a Rancour in Hugenius and that according to the French custome, he wrote ex animo vitipendendi’. So Huygens caustically protested to Oldenburg that Collins' document ‘ought not to be called “The State of a Controversy,” but a decision in favor of Mr. Gregory against [him]; and to judge on this basis would be to judge after hearing only one side of the case.’ Even more emphatic was his demurring to Moray that he had received little satisfaction from the report that, for all intents and purposes, appeared to have been dictated by Gregory. Indignantly, Moray retorted that he had attempted to intercede as a friend, not act as a judge; and with this the correspondence between Huygens and Moray terminated.^17. Nevertheless, Huygens chose to drop the matter and carry on the exchange with Oldenburg, not

12. O.C., vol. 4, pp. 318, 330-331; vol. 6, pp. 154, 228-231, 240-243, 272-276; Journal des Sçavans n^o 5 (2 July 1668), pp. 361-368; Philosophical Transactions 3, n^o 37 (13 July, 1668), pp. 732-735. See E.J. Dijksterhuis, ‘James Gregory and Christiaan Huygens’. In: James Gregory Tercentenary Memorial Volume, ed. H.W. Turnbull (London, 1939), pp. 478-486.

13. Philosophical Transactions 7, n^o 33 (16 March 1667/8), pp. 640-641; Oldenburg, Correspondence (n. 1), vol. 5, pp. 3-4; O.C., vol. 6, pp. 253-255.

14. Gregory Memorial Volume (n. 12), pp. 51-53; O.C., vol. 6, pp. 296-298.

15. Gregory Memorial Volume (n. 12), pp. 54-60, 77; Oldenburg, Correspondence (n. 1), vol. 5, p. 362; O.C., vol. 6, p. 268.

16. For Wallis's paper see O.C., vol. 6, pp. 282-289; for Collins's paper see ibid. pp. 372-376.

17. Gregory Memorial Volume (n. 12), pp. 59-60; Oldenburg, Correspondence (n. 1), vol. 5, p. 452; O.C., vol. 6, pp. 393-394, 423.

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least because the Royal Society was pursuing at precisely the same time its ambitious investigation of the laws of motion, a subject in which Huygens prided himself as being peerless.

‘When certain Fellows of the Royal Society proposed at the last meeting that it would be appropriate to make some experiments on the nature and the laws of motion,’ Oldenburg began his letter of 26 October 1668, ‘others remarked that Mr. Huygens thought he had already discovered a theory which explained all kinds of phenomena concerning motion.’ Mixing flattery with insinuation concerning the possible loss of credit, Oldenburg urged Huygens to join in the Society's work:

‘I was ordered to let you know what had passed, and to entreat you, as one of their number, to think fit to inform them when you would bring your speculations and observations on this subject before the public. Further, in case you had not yet reachd the point of having them printed, I was to ask you to be so good as to communicate to them your hypothesis of motion, which they would endeavor to examine by every kind of experiment, and to register it as the offspring of your mind. I hope, Sir, that you will not scruple to grant the Society (of which you are one of the leading members) what is thus requested of you, for our philosophers have purposely suspended the pursuit of this question (so important to all science) in order neither to forestall you, nor to lose any time upon a matter which is thought to be already explored and settled. You will thus oblige me, Sir, if you will convey your decision on this point to me as soon as you conveniently can, so that I may render an account to the Society of the commission which it entrusted to [me].’^18.

A similar letter was dispatched to Christopher Wren and within a week both wrote back agreeing to communicate their results.

Unknown to Huygens, however, some members of the Society had more than scientific inquiry in mind. In a follow-up letter to Wren, Oldenburg added that ‘some of that company (yr particular friends) did wish, that you should hasten as much as is possible yt reexamination, least you should be prevented by strangers, & to impart wth wt speed you might, the rules & axioms, you have raised allready from such experiments, as you have formerly tryed; to ye end; yt the glory might redound to persons of the English nation for ye establishment of yt important subject.’ Though Huygens was not aware of this, the shrewed Dutchman knew with whom he was dealing and already in his initial reply to Oldenburg he had raised the issue of credit and priority, explicitly telling the Secretary of the Royal Society that he was willing to communicate his rules and theorems ‘since they promise me to examine them, to verify them with their experiments, and to give them a place in their registers, which is indubitably a very certain way of ensuring that no one is deprived of the honor of his own discoveries.’^19.

Oldenburg proceeded cautiously. Having received Huygens' first batch of propositions on 4 January 1668/9, he immediately wrote back to acknowledge their safe arrival, informing Huygens at the same time that he would open the letter only in the presence of Viscount Brouncker or at the next meeting of the Society. He also promised to send Huygens a copy of Wren's paper which had already been registered. When it arrived two weeks later, Huygens was gratified to read the paper since, he told Oldenburg, it agreed entirely with his results ‘and these are certainly the correct ones.’ In fact, so pleased was Huygens with this turn of events that he also promised to send other theorems on the same subject. He then seized the op-

18. Oldenburg, Correspondence (n. 1), vol. 5, p. 104.

19. Ibid., pp. 135, 127.

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portunity and proposed the institution of a procedure that would secure for his discoveries priority and credit irrespective of whether they were published first:

‘as I have noticed that very frequently in cases of the discovery of new truths one is forestalled by the first who make them public, for lack of means of making it known that one has discovered the same thing, I have asked these gentlemen (in order to relieve both them and me of such qualms) to agree to my sending them in cipher or anagram form what I may have available in the way of propositions and new inventions, these to be interpreted to them at a later time, and let those of them who have anything similar do the same. For these ciphers being preserved on both sides in register books will serve in the future not only for us, but also in respect of men in other countries, to assure to everyone the honor due to him, which in my opinion ought to be equally assigned to all those who find out a thing for themselves without regard to the time [when it was done], provided that they can state firmly that they have made the discovery without any assistance.’^20.

By return mail, however, Huygens received a copy of the Philosophical Transactions for January 1669, in which Oldenburg inserted the papers by Wren and Wallis, without even mentioning that he had also received Huygens' rules of motion. Somewhat disingenuously, Oldenburg excused the omission by telling Huygens that ‘If I had your permission, and if you had communicated a summary of all your reflections on the subject, I would have enriched this same number of the Transactions with them most willingly.’ Attempting to sweeten the blow, Oldenburg informed Huygens that the Society ‘very much approves of what you propose as a way of ensuring to everyone the honor of his own discoveries and inventions’.^21. Huygens must have been distraught by the arrival of the package from London as it included not only the issue of the Philosophical Transactions and Oldenburg's rather lame excuses, but also Collins's ‘report’ on the controversy between Gregory and Huygens. For five weeks Huygens remained silent. Only then, after he had received two additional letters from the anxious Oldenburg, did Huygens finally respond. Coldly, he pointed out to the Society's Secretary that no permission was required for publishing the basic fact that the Society received and registered Huygens' rules, and that they were ‘substantially the same’ as those of Wren: ‘For having nowhere made any mention of myself,’ he protested, ‘you have to all intents and purposes anticipated me in the publication of those rules, although you had made me hope for the contrary when you asked me to open relation with gentlemen on the question of motion.’ In order to establish his priority, Huygens continued, he had just published in the Journal des Sçavans a summary of his discoveries, though he ‘had no wish to complain of this slight injustice of which I have just written, and so I related only what had passed between us so that no one could accuse me of having copied my rules from those of Mr. Wren.’^22.

Oldenburg immediately seized the opportunity to cast off all blame for not having published Huygens' paper himself. ‘I must begin by confessing,’ he replied indignantly, ‘that when I read your letter of 30 March, I was extremely surprised to find myself there accused of injustice, after having taken so much trouble to do everything I had promised you to do and all that you asked of me.’ In fact, the Society registered his rules and its members were busy examining them experimentally. ‘But as for the failure to publish your theory or a summary of it, this (to speak frankly) is your own fault. You had the Journal des Sçavans as a means for getting

20. Ibid., pp. 318, 362.

21. Ibid., pp. 373-374. Oldenburg should well have apologized, for, if Collins is to be believed, something a little more sinister had transpired behind the scenes. When Huygens' ‘Theories of Motion, Percussion and Collision’ arrived, Collins told Gregory, ‘it seemes nothing more is discovered then what Dr Wren formerly imparted ... so they have returned Huygen's thanks, but ordered Dr Wren's paper to be printed in the Transactions.’ (Gregory Memorial Volume (n. 12), p. 65).

22. Oldenburg, Correspondence (n. 1), vol. 5, p. 452.

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it printed, if you had wished to do so, as quickly as was done here for Messrs. Wallis and Wren in the Philosophical Transactions.’ A month later Oldenburg did publish the Latin version of Huygens' rules of motion, but prefaced it with an historical introduction intended to protect English interests: ‘Before these Rules of Motion be here deliver'd, ‘tis necessary to preface something, whereby the worthy Author of them may receive what is unquestionably due to him, yet without derogating from others, with whom in substance he agreeth.’^23.

Huygens opted not to further pursue the matter, in part because Oldenburg had assured him that there was general agreement in the Society concerning the truth of his rules.^24. But he rescinded his earlier design to dispatch his other propositions to the Society. Instead, in late August 1669 he sent Oldenburg fourteen anagrams he wished the Secretary to register in the Society's books according to the ‘method which [he] proposed to avoid disputes and to give everyone his due in the discovery of new things.’ When this is done, Huygens continued,

‘considerations of where it is will create confidence everywhere, when this kind of deposit is reclaimed, that there is no fraud nor deceit involved, and I hope that this method of registration may become commonly known to and practised by all those involved in mathematics, so that no one ever say, when seeing a proposition of something new, that he had also discovered it.’^25.

During the second half of 1669 Huygens carried on a cordial scientific exchange with Oldenburg, and though he was informed of a few instances in which members of the Society were treading on his domain - Wren's method of printing in facsimile is one, Hooke's work on pendulum and clocks another - no conflict occurred. Still, the development of events ever since he had reestablished his exchange with the Royal Society appears to have confirmed his jaundiced view of the English. Indeed, less than a month before sending the account which opened the present essay, Vernon conveyed a different message, cautioning Oldenburg not to be too open in his communications with Huygens:

‘you had done better not to have communicated your intentions about measuring the Earth to him. For though he bee a very knowing & worthy person, Yet hee hath a great zeale for the honour of The French academie even to Jealousie & I believe (whether it bee Mr Gregory or who it is that hath toucht him) that hee is a little suspitious of the workings of the English nation. & thinketh that you would take patterne by them.’^26.

For the moment, though, Huygens' deep concern for the fate of his discoveries forced him to lay aside his resentment and suspicion of the English. He was fully cognizant of the fact that the Royal Society alone had adopted formal procedures aimed at establishing credit for discoveries and, believing himself faced with imminent death, he was intent on ensuring immortality by entrusting his discoveries to the Society.

Huygens, of course, did not die, and the long process of convalescence in Holland also contributed to soothing the relations with the Society. By June 1671 Huygens was back in Paris from whence he continued the cordial and productive exchange with Oldenburg. The latter regularly supplied him with copies of the Philosophical Transactions and with the latest scientific news (such as the Alhazen problem and Newton's telescope^27.), often endeavouring to solicit Huygens' judg-

23. Ibid., p. 465; ‘A Summary Account of the Laws of Motion, communicated by Mr. Christian Hugens in a Letter to the R. Society, and since pr in the Journal des Scavans of March 18, 1669. st. n.’. In: Philosophical Transactions 4, n^o 46 (12 April, 1669), 925-928.

24. On 19 May 1669 Huygens wrote Oldenburg: ‘please let us speak no more of that, since in the end the result was not unfortunate nor disadvantageous for me, for I do not believe that I share the honor of this discovery with Mr. Wren but rather that it belongs wholly to each of us.’ (Oldenburg, Correspondence (n. 1), vol. 5, p. 556).

25. Oldenburg, Correspondence (n. 1), vol. 6, p. 212.

26. Ibid., pp. 435-436.

27. Perhaps it is not insignificant to observe that Oldenburg told Newton he hastened to send the news concerning Newton's telescope to Huygens ‘thereby to prevent the arrogation of such strangers, as may perhaps have seen it here’ (The Correspondence of Sir Isaac Newton, ed. H.W. Turnbull et al., 7 vols. (Cambridge, 1959-1977), vol. 1, p. 73).

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ment on these and other issues. But behind the veneer of normalcy new tensions were brewing. Already in late 1671, John Wallis published his Mechanica, wherein he attributed the first observation of the phenomenon of anomalous suspension to Boyle. Huygens did not complain, but in July 1672 he published his own account in the Journal des Sçavans.^28. Then, during the spring of 1672 Oldenburg asked Huygens to comment on both Newton's theory of colors and Wallis' double method of tangents. Huygens' compliance with such requests proved fateful.

Huygens articulated his criticism of Newton's theory in four consecutive letters, each more critical than the previous. But although Oldenburg promptly apprised Newton of such criticism, the Cambridge professor did not respond for over six months, except to express irritation and announce his desire to resign from his Fellowship. In contrast to his hackneyed treatment of Gregory, however, from the start Oldenburg was fully committed to Newton's cause and he desperately attempted to appease Newton, apologizing to him for the criticism of both Huygens and Hooke: ‘I could heartily wish,’ he urged Newton in one of his letters, ‘you would passe by the incogruities, yt may have been committed by one or other of our Body towards you, and consider, that hardly any company will be found in the world, in wch there is not some or other yt wants discretion. You may be satisfied, that the Body in general esteems and loves you, wch I can assure you of’.^29. Unfortunately, Newton's reply was rather vehement and, though not as acerbic as his rebuttal of Hooke, was sufficiently testy to force Oldenburg to apologize to Huygens in advance for the tone: ‘I can assure you that Mr. Newton is a man of great candor, as also one who does not lightly put forward the things he has to say.’ Huygens, however, was unwilling to be chastized like a schoolboy: ‘Touching the Solutions, given by M. Newton to the scruples by me propos'd about his Theory of Colors, there were matters to answer them, and to form new difficulties; but seeing that he maintains his opinion with so much concern, I list not to dispute’.^30. Though he added a few more reflections Huygens desisted from further responding to Newton's more tempered rebuttals and the relations between the two was not renewed until Huygens' third visit to England in 1689.

While Newton had only recently come to Huygens' attention, John Wallis' relations with the Dutchman dated back to the 1650s and the epistolary exchange between the two is indicative of the esteem with which Wallis regarded Huygens. Only a few years earlier, it was noted above, Wallis had also been an animated champion of Huygens' cause in the debate with Gregory. Given their amity, the rift between the two proved more dramatic than the one with Newton. Relations soured following the publication of Wallis' two methods of tangents in the March 1672 issue of the Philosophical Transactions. As usual Huygens' opinion was solicited by Oldenburg. Huygens waited for more than five months before returning a cutting verdict: Wallis' first method was indistinguishable from that of Fermat - and he (Huygens) had a better one - while the second ‘was not unknown to [him] either’, but then, again, he had ‘another method, better and much more compendious than all those for tangents’. Wallis, who rarely tolerated criticism and who was in any case over-sensitive to his priority, was deeply offended; and though he told Oldenburg that he did not wish to enter into a dispute with Huygens over this matter, resentment was festering.^31.

With the publication in 1673 of the Horologium Oscillatorium the tension came to

28. Following the publication of Huygens' account, Wallis wrote Oldenburg that ‘since the first discovery of ye Phenomenon was in our own Society, I would willingly that ye true Cause should be there determined allso; and not that we should be therein prevented from abroad.’ However, he continued, he did not wish that his remarks on Huygens' article and the issue in general give occasion to ‘any difference or contest, because ye businesse is not worth it; & I have a kindness for monsr Hugens, which makes me not desirous of any contest with him.’ (Oldenburg, Correspondence (n. 1), vol. 9, pp. 322-323).

29. Oldenburg, Correspondence (n. 1), vol. 8, p. 637; vol. 9, pp. 119, 249, 383; Newton, Correspondence (n. 27) vol. 1, pp. 243, 255-256, 262, 264-266, 284.

30. Oldenburg, Correspondence (n. 1), vol. 9, pp. 571, 676.

31. Philosophical Transactions 7, n^o 81 (25 March, 1672), 4010-4016; Oldenburg, Correspondence (n. 1), vol. 9, pp. 249-250, 276. As noted above (see n. 28), Wallis was to reiterate his disinclination to dispute with Huygens two weeks later.

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a head. In fact, that publication provoked several reactions. For example, anticipating the book's imminent publication, Viscount Brouncker rushed into print his own proof of the isochronism of the cycloid, to which Oldenburg prefaced a statement claiming an independent discovery for the President of the Royal Society. Then, after he had received a copy of the book, Oldenburg immediately wrote Huygens to claim for Hooke priority for discovering the conical pendulum, as well as for the invention of an instrument ‘for measuring the speed of fall of bodies.’^32. But it was Wallis who took center stage this time. The Oxford professor was doubly offended: ‘you not only seem to insinuate a charge of bad faith directly against myself,’ he remonstrated to Huygens on 30 May 1673, ‘but seem rather doubtful whether William Neile fully achieved [the rectification of the semicubic parabola] that, as you admit, he nearly accomplished.’ ‘You are ill acquainted with the spirit of the English’, Wallis concluded. ‘Whatever may be thought of the French or the Dutch, certainly the English are not thus given to continual pursuit of fame.’ And this was only the beginning. Three weeks later Wallis drafted a Latin letter to Oldenburg, perhaps expecting its publication in the Philosophical Transactions where, in addition to further defending both Neile's and Wren's contributions, and charging Huygens with knowing this, he again accused the latter of becoming too French: ‘Why Huygens should have put up pretences about all this can only be because he has been rather less than impartial towards us, being perhaps influenced in this by the French, since formerly he used to behave more fairly. And this even when I have acted so fairly towards him and his countryman [heuraet]’.^33.

Though Oldenburg did not publish the letter, he conveyed to Huygens the grievances of the English, adding another by Kincardine, then in London, that it was he who first suggested to Huygens to try pendulums at sea when the latter ‘had the greatest possible difficulty in believing that this could be put into practice at sea.’ Though cognizant of the gathering storm, Huygens refused to capitulate when explaining his position to Oldenburg and Wallis. The latter he chided for failing to publish Neile's discovery, ‘for this would have been much better than laying a claim to it afterwards.’ Besides, he reminded Wallis, the English are just as covetous of praise as are the French or the Dutch. Oldenburg made a valiant effort to mediate. On 4 August he assured Huygens that he would ‘never fail to contribute all that [he could] to maintain mutual goodwill between distinguished people everywhere’, adding his hope that Huygens would not ‘take it in bad part’ the publication of Newton's response to Huygens' criticism of the theory of colors.^34. Huygens did not respond. Nor did he react to further assaults by Wallis who not only wrote another spirited defense of Neile, published by Oldenburg in the November 1673 issue of Philosophical Transactions, but was the true author of another article in the same issue, the one attributed to Brouncker, confirming Neile's discovery.^35.

Oldenburg continued to be unwavering in his efforts to spur Huygens to carry on his correspondence, regularly dispatching to Paris scientific news, copies of the Philosophical Transactions, and books by members of the Society. By March 1674 Oldenburg was beside himself:

‘Here once again is my journal, which I send to you to complete the century, and to try whether I can arouse you, who, to speak frankly, owes me five or six letters. You

32. Philosophical Transactions 8, n^o 94 (19 May 1673), p. 6032; Oldenburg, Correspondence (n. 1), vol. 10, p. 2. Even as early as 1671 John Collins attempted to incite Newton into publication in order to forestall Huygens. See The Mathematical Papers of Isaac Newton, ed. D.T. Whiteside, 8 vols (Cambridge, 1967-1981), vol. 3, p. 23.

33. Oldenburg, Correspondence (n. 1), vol. 10, pp. 4, 41-42.

34. Ibid., pp. 66-67, 72-74, 113-114; O.C., vol. 7, pp. 339-340.

35. Oldenburg, Correspondence (n. 1), vol. 10, pp. 279-282, 291-292; Philosophical Transactions 8, n^o 98 (17 November, 1673), pp. 6146-6150. For further complaints by Wallis see Oldenburg, Correspondence (n. 1), vol. 10, pp. 525-526, 564-566.

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seem entirely to have forgotten the interest which you have in the Royal Society or else you take in bad part (which is what nevertheless I should not easily wish to think) that one or two of this body take the liberty of speaking frankly of some particulars which you gave to the public. However it may be, you may be assured that our Fellows do not fail to have the same esteem which they have always had of your merit, and which they demonstrated from time to time; in a manner which cannot fail to please you.’^36.

But it was only in May 1674, nearly a year since he had last written, that Huygens finally responded. The cause for the long silence, he informed Oldenburg, ‘is nothing but that I saw that my letters only served to put me wrong with those gentlemen over there, some not taking in good part the liberty I employed in speaking my opinion about their works and in raising objections to them, others framing for themselves other sources of discontent, which I did not expect at all.’ Oldenburg became indignant again:

‘It gives me decided displeasure to find by yours of 15th May that you seem to have let your correspondence with us lapse because of the misunderstandings which you believe have been born out of your freedom towards the Fellows. I can assure you that those who know you here do not fail to continue the same affection and esteem for your person and merits always; and they only take the same liberty towards you, which you takes towards them, which is, to speak frankly their opinions of your works, and sometimes to correct the blunders which they think are committed there over the priorities of certain inventions. “We grant indulgence, and we seek it in return.” This being practiced on both sides, it is necessary, it seems to me, to maintain steadily the same friendship, and to do nothing which can enfeeble or set at variance the forces of the intelects who work successfully for the advancement of science.’^37.

Rhetoric aside, however, Oldenburg was truly hoping to normalize the relations between Huygens and the Royal Society, but this was not to be. Wallis, for one, was not to be pacified. ‘If Mr Hug. be out of humour,’ he quipped in June 1674 in response to the news that Huygens resumed the correspondence with Oldenburg, ‘I cannot help it; The occasion did not begin on our side, nor have we given him any just occasion so to be.’ Six months later he was irked by ‘Hugenius's Reflexions on Mr Hook's Lecture [An Attempt to Prove the Motion of the Earth from Observations], in ye Transactions of July. For wheras hitherto ye Jesuites &c have only desired a Parallax, to a full conviction of ye Earth Motion; he now studies to pick a hole in that allso. But I find, since his being Frenchified, his humour is strangely altered from what it was wont to be.’^38. But it was Robert Hooke who emerged to occupy center stage.

Constraints of space do not permit a thorough analysis of the events of the mid-1670s and unfortunately the re-evaluation of the relations between Huygens and Hooke must be left for another occasion.^39. It should be emphasized, however, that the violent eruption between Huygens and Hooke was not simply a debate over priorities and profits between two talented and touchy individuals. At least as important was the fact that Huygens was caught up in the crossfire between two opposing factions in the Royal Society and Hooke's attacks were directed as much against Oldenburg as against Huygens; likewise, the equally rigorous attempts to discipline Hooke were motivated as much by considerations of Royal Society politics as by the desire to defend Huygens' honor.

In the end, however, Oldenburg's death in September 1677 and the ousting

36. Ibid., pp. 490-491.

37. Oldenburg, Correspondence (n. 1), vol. 11, pp. 2-3, 25.

38. Ibid., pp. 37, 155; Philosophical Transactions 9, n^o 105 (20 July 1674), p. 90.

39. For recent discussion and bibliography, see M. Wright, ‘Robert Hooke's Longitude Timekeeper’. In: Robert Hooke: New Studies, eds. M. Hunter and S. Schaffer (Woodbridge, 1989), pp. 63-118; R. Illife, ‘In the Warehouse’: Privacy, Property and Priority in the Early Royal Society'. In: History of Science 30 (1992), pp. 29-68.

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several months later of Brouncker from the Presidency of the Royal Society left Huygens with few friends in the Society. Nor was the election of Hooke and Nehemiah Grew as Secretaries auspicious for the continuation of cordial relations. Huygens did receive the form letter dispatched to all of Oldenburg's former correspondents, requesting them to carry on their exchange with the Society, and he responded favorably to it on 6 June 1678, ‘expressing his desire to be informed of the inventions and proceedings of the Society, as he had formerly been by Mr. Oldenburg, and promising in return to communicate to them whatever he should think worthy of their notice.’ Huygens further intimated that of late ‘he had been employed some thoughts about improving microscopes, being prompted by the discovery of Hammius.’ After the letter was read at the weekly meeting ‘it was ordered, that care should be taken to answer this letter, and to continue this correspondence with Monsr. Huygens.’ Grew dully dispatched a civil letter on 26 July but Huygens, it seems, failed to respond, thereby effectively terminating his relationship with the Royal Society.^40. For the next decade and a half formal relations did not exist and Huygens had to rely on Denis Papin, Leeuwenhoek, family members, and occasional visitors for scraps of news on the Society's work. Then, during his third visit to England in the summer of 1689 Huygens attended a couple meetings at Gresham College; nevertheless, Huygens made no attempt to correspond subsequently with the Society, and its members exhibited no interest in soliciting his participation in their work.

40. Birch, History (n. 4), vol. 3, p. 415; O.C., vol. 8, pp. 84-85.