Out of the Shadow of a Giant
Page 12
There is no specific reason known why Oldenburg should have taken a dislike to Hooke, but a natural supposition is that he became jealous of Hooke’s success. Oldenburg was a would-be scientist, who had known Hooke as Boyle’s mere assistant and saw him rise to heights that Oldenburg himself could never achieve. Whatever the reasons, the antagonism was beginning to show by March 1666, when Boyle objected to Oldenburg’s failure to give Hooke due credit for his depth-sounding device in an article Oldenburg wrote for the Philosophical Transactions. Since Boyle knew both men so well, the criticism has to be taken seriously. It is also now well documented that, as Hooke suspected, Oldenburg passed on details of Hooke’s work on chronometers to Huygens. Jumping ahead a little, in 1676 Oldenburg published in the Philosophical Transactions a translation of a letter from Huygens describing his latest pocket watch:
the invention consists of a spring coiled into a spiral, attached at the end of its middle to the arbor of a poised, circular balance which turns on its pivots; and at its other end to a piece that is fast to the watch-plate. Which spring, when the Ballance-wheel is once set a going, alternately shuts and opens its spires, and with the small help it hath from the watch-wheels, keeps up the motion of the Ballance-wheel, so as that, though it turn more or less, the times of its reciprocations are always equal to one another.
Interesting to compare that with the description of Hooke’s watch from 1668 (see page 23), mention of which Oldenburg ‘forgot’ to include in the records of the Royal. It may or may not be that Huygens hit on similar ideas to Hooke independently, but it is certain that Hooke had the ideas first, and was done out of due credit by the machinations of the Secretary of the Royal. Indeed, in 1675 Hooke had a watch made to his own design by Thomas Tompion, a leading London watchmaker, and presented it to the King. It was inscribed in Latin, ‘Hooke invenit 1658. Tompion fecit 1675.’fn9 In his diary, Hooke wrote: ‘With the King and shewd him my new spring watch, Sir J. More and Tompion there. The King most graciously pleasd with it and commended it far beyond Zulichems.’fn10 The same year, he wrote to Aubrey: ‘I have many things which I watch for an opportunity of Publishing, but not by the Royal Society. Oldenburg his snares I will avoid if I can.’ But in the end, neither Hooke nor Huygens was granted a patent.
In fact, Oldenburg ‘had previous’, as they say in TV detective stories, although he singled Hooke out for special attention. Putting it charitably, Jardine says that he had the ‘instinct of the adept publicist’, eager to whip up controversy and thereby ‘spice up exchanges of letters which would later find their way into his published Philosophical Transactions.’ She cites the example of a letter from the French scientist Adrien Auzout, sent to Hooke via Oldenburg. Oldenburg highlights points for Hooke to respond to, with comments such as ‘What say you to this?’ and ‘A handsome sting again will be necessary.’ And in correspondence from Oldenburg to foreign scientists such as Huygens he describes Hooke as ‘a man of unusual humour’ and suggests that his genius (which even Oldenburg cannot deny) comes close to crossing the line into madness. On 20 May 1677, Hooke had reached breaking point, and considered resigning from the Royal; he wrote in his diary ‘Saw the Lying Dog Oldenburg’s transactions. Resolved to quit all employments and to seek my health.’ But in the end he decided to stick it out, and not long afterwards Oldenburg died. It is against that background that we can return to our story of what happened when Newton, encouraged to come out of his shell by the enthusiastic response of the Royal to his telescope, was persuaded to send them a letter detailing his ideas concerning light and colour.
This was in 1672, when Hooke was heavily occupied with his work as surveyor and architect, and the Royal had not yet been able to return to Gresham College. Newton, by contrast, resided in the proverbial academic ivory tower, with nothing to distract him from natural philosophy, unless he chose to do something else.fn11
Hooke was the leading expert on light and optics, and made a careful study of Newton’s letter before reporting back to the Royal. The key difference between Hooke’s model of light and Newton’s model was that Newton regarded white light as being a mixture of colours even when it was not passing through the glass of a prism (or lens), while Hooke thought that the colours did not exist until the light interacted with the glass. Newton also favoured the idea that light was a stream of particles, but Hooke thought of it as a wave. Even so, Hooke was willing to accept that Newton’s hypothesis worked as a possible description of what happened to light when it passed through a prism, but he suggested that it was no better than other hypotheses, in particular his own. He granted that Newton’s hypothesis was ‘very subtill and ingenious’ but concluded ‘I cannot think it to be the only hypothesis.’ Here is a flavour of Hooke’s letter:
But why there is a neccessity, that all those motions, or whatever else it be that makes colours, should be originally in the simple rays of light, I do not yet understand the necessity of, no more than that all those sounds must be in the air of the bellows, which are afterwards heard to issue from the organ-pipes; or in the string, which are afterwards, by different stoppings and strikings produced; which string (by the way) is a pretty representation of the shape of a refracted ray to the eye; and the manner of it may be somewhat imagined by the similitude thereof: for the ray is like the string, strained between the luminous object and the eye, and the stop or fingers is like the refracting surface, on the one side of which the string hath no motion, on the other a vibrating one. Now we may say indeed and imagine, that the rest or streightness of the string is caused by the cessation of motions, or coalition of all vibrations; and that all the vibrations are dormant in it: but yet it seems more natural to me to imagine it the other way.
These were far from being unreasonable comments, even if Hooke’s tone tended to be rather condescending. Oldenburg sent a copy of Hooke’s critique to Newton, but declined to publish it alongside Newton’s own letter in the Philosophical Transactions. Hooke repeated some of Newton’s experiments for the Royal, in particular the one that showed that a rainbow pattern of colours produced when white light passed through a prism could be recombined to make white light by a second prism. But he stuck firmly to his argument that waves of white light could be made up from many different waves, just as the sound produced by a musical instrument could be a combination of different sounds. In this, we now know, he was more right than Newton.
Prompted by Oldenburg, Newton, who was in any case a prickly personality who could not bear criticism, hit back in a long letter addressing all of Hooke’s points in turn, and claiming that he found it easier to imagine white light being split into colours and recombined if it was made of different coloured particles. And he pointed out that light, unlike waves, travels in straight lines.
Newton seems to have got more and more angry as he drafted and redrafted the letter. Many copies survive, and as he ‘improved’ the document he added more and more references to Hooke, making them increasingly offensive. As Newton’s biographer Richard Westfall has put it, Newton ‘virtually composed a refrain on the name Hooke’.
Oldenburg was delighted. He read out the juicy bits of the letter to the Royal on 12 June 1672, and published the whole diatribe in his journal, without giving Hooke the right of reply. Feeling that it was futile to take up the issue with Oldenburg, Hooke wrote to Lord Brounckerfn12 to express his distress at having provoked so violent a reaction. ‘I was soe far from imagining that Mr. Newton should be angry that I cannot yet believe that he is’, he wrote; in matters of philosophical discussion ‘a freedome & liberty of Discoursing and arguing ought to be Tollerated’, and he claimed that he would be happy to see his own hypothesis disproved if that were to be the case. All he sought was the truth about nature.
But the most remarkable thing about this letter, which is not as widely known as it deserves to be, is that he goes on to describe a crucial experiment that he had demonstrated to Brouncker. Referring to a narrow beam of sunlight obtained by making a small hole in a window blind, he says
:
By placing the Edge of a razor in the cone of the Suns radiation at a pretty distance from ye hole … and by holding a paper at some Distance from the razor in the shadow thereof, your Lordship plainly saw, that the Light of the sun Did Deflect very deep into the shadow.
This was proof, in 1672, that light travels as a wave. Like waves on the sea bending round an obstruction such as a rock, light waves bent around the edge of the razor and into the shadow. But it was not until the early nineteenth century that the experiments of Thomas Young and Augustin Fresnel overthrew the ‘corpuscular theory’ of light, which had held sway for nearly 150 years almost solely on the basis of Newton’s reputation. By the end of the seventeenth century, his status as a giant of science (the giant of science) was so great that anything he had said ‘must be true’ in the eyes of lesser mortals.
Hooke was not the only one to take issue with Newton about his light hypothesis. Huygens read Newton’s letter in the Philosophical Transactions, and wrote to him with some comments and criticisms of his own (Huygens was a leading proponent of the wave model of light). He received such an unpleasant reply that he told Newton ‘seeing that he maintains his doctrine with some warmth, I do not care to dispute’, and gave up the correspondence. For his part, Newton, unable to cope with the kind of frank and fearless discussion that characterised scientific debates of the time, withdrew back into his ivory tower, threatened to resign from the Royal, and laid low for the next couple of years. Hooke carried on as usual, working away at a variety of projects including a calculating machine (based on a design by the German mathematician Gottfried Wilhelm Leibnizfn13) that used geared wheels to carry out multiplication to twenty places, but which proved too complicated to be practical.
Newton had calmed down enough by 1675 to attend several meetings of the Royal, where among other things he saw and heard Hooke describe the diffraction experiment mentioned in the letter to Brouncker. This was probably the first time he had aired the idea in public. Newton was not impressed, and dismissed it as only a new kind of refraction, to which Hooke replied that even if that were the case, it was indeed new.
Early in December 1675, Newton sent Oldenburg a long letter (a scientific paper in modern terminology) on light, which the Secretary read out to the Royal in two parts on successive weeks. As well as setting out his stall and once again responding to Hooke’s arguments, Newton included a sneering reference to Hooke’s razor experiment, claiming that it had previously been described by the Italian Francesco Grimaldi, and others. Even Newton was decent enough to add ‘I make no question but Mr Hook was the Author too’, meaning that Hooke made the discovery independently, but the arch-stirrer Oldenburg left that sentence out of his presentation.
Now Oldenburg fanned the flames of the dispute, or, as Hooke would later put it, he ‘kindled cole’.
Oldenburg told Newton (untruthfully) that Hooke had claimed that essentially everything described in Newton’s letter was contained in Micrographia, which Newton ‘had only carried farther in some particulars’. Until that point, Newton seems to have been willing to acknowledge his genuine debt to Hooke. In the second part of his long paper, he had said that Micrographia contained ‘very excellent things concerning the colours of thin plates, and other natural bodies, which I have not scrupled to make use of so far as they were for my purpose.’ But in response to Oldenburg’s mischief-making, at the end of 1675 and early in 1676 he sent two further letters to the Secretary, saying that Hooke’s discussion of light and colour was not original, but largely lifted from Descartes, and that nothing Newton had borrowed from Micrographia was actually Hooke’s own work. Oldenburg read out the attack on Hooke to the Royal on 20 January 1676, without anyone, least of all Hooke, being warned in advance. Hooke realised that Newton was being manipulated by Oldenburg, and wrote in his diary that ‘Oldenburg kindle cole.’ He immediately wrote to Newton to soothe him, initiating an exchange of letters so important (and so often misunderstood) that it is worth repeating in full.fn14
These to my much esteemed friend, Mr. Isaack Newton, at his chambers in Trinity College in Cambridge.
Sir., – The hearing a letter of yours read last week in the meeting of the Royal Society, made me suspect that you might have been some way or other misinformed concerning me; and this suspicion was the more prevalent with me, when I called to mind the experience I have formerly had of the like sinister practices. I have therefore taken the freedom, which I hope I may be allowed in philosophical matters to acquaint you of myself. First, that I doe noe ways approve of contention, or feuding or proving in print, and shall be very unwillingly drawn to such kind of warre. Next, that I have a mind very desirous of, and very ready to embrace any truth that shall be discovered, though it may much thwart or contradict any opinions or notions I have formerly embraced as such. Thirdly, that I do justly value your excellent disquisitions, and am extremely well pleased to see those notions promoted and improved which I long since began, but had not time to compleat. That I judge you have gone farther in that affair much than I did, and that as I judge you cannot meet with any subject more worthy your contemplation, so I believe the subject cannot meet with a fitter and more able person to inquire into it than yourself, who are every way accomplished to compleat, rectify, and reform what were the sentiments of my younger studies, which I designed to have done somewhat at myself, if my other more troublesome employments would have permitted, though I am sufficiently sensible it would have been with abilities much inferior to yours. Your design and mine are, I suppose, both at the same thing, which is the discovery of truth, and I suppose we can both endure to hear objections, so as they come not in a manner of open hostility, and have minds equally inclined to yield to the plainest deductions of reason from experiment. If, therefore, you will please to correspond about such matters by private letters, I shall very gladly embrace it; and when I shall have the happiness to peruse your excellent discourse, (which I can as yet understand nothing more of by hearing it cursorily read,) I shall, if it be not ungrateful to you, send you freely my objections, if I have any, or my concurrences, if I am convinced, which is the more likely. This way of contending, I believe, to be the more philosophical of the two, for though I confess the collision of two hard-to-yield contenders may produce light, [yet] if they be put together by the ears by other’s hands and incentives, it will [produce] rather ill concomitant heat, which serves for no other use but . . . . . . kindle – cole. Sr, I hope you will pardon this plainness of, your very affectionate humble servt,
Robert Hooke
This could hardly be more conciliatory, and in the genuine circumstances of Hooke’s busy life we can accept his wish to make it clear that in other circumstances he might have taken things further himself. At first sight, Newton’s reply is equally conciliatory.
‘Cambridge, February 5, 1675–6.
DR. Sir, – At the reading of your letter I was exceedingly pleased and satisfied with your generous freedom, and think you have done what becomes a true philosophical spirit. There is nothing which I desire to avoyde in matters of philosophy more than contention, nor any kind of contention more than one in print; and, therefore, I most gladly embrace your proposal of a private correspondence. What’s done before many witnesses is seldom without some further concerns than that for truth, but what passes between friends in private, usually deserves the name of consultation rather than contention; and so I hope it will prove between you and me. Your animadversions will therefore be welcome to me; for though I was formerly tyred of this subject by the frequent interruptions it caused to me, and have not yet, nor I believe ever shall recover so much love for it as to delight in spending time about it; yet to have at once in short the strongest objections that may be made, I would really desire, and know no man better able to furnish me with them than yourself. In this you will oblige me, and if there be any thing else in my papers in which you apprehend I have assumed too . . . . . . If you please to reserve your sentiments of it for a private letter, I hope
you [will find that I] am not so much in love with philosophical productions, but that I can make them yield . . . . . . But, in the mean time, you defer too much to my ability in searching into this subject. What Descartes did was a good step. You have added much several ways, and especially in considering the colours of thin plates. If I have seen farther, it is by standing on the shoulders of giants. But I make no question you have divers very considerable experiments beside those you have published, and some, it’s very probable, the same with some of those in my late papers. Two at least there are, which I know you have often observed, – the dilatation of the coloured rings by the obliquation of the eye, and the apparition of a black spot at the contact of two convex glasses, and at the top of a water-bubble; and it’s probable there may be more, besides others which I have not made, so that I have reason to defer as much or more in this respect to you, as you would to me. But not to insist on this, your letter gives me occasion to enquire regarding an observation you was propounding to me to make here of the transit of a star near the zenith. I came out of London some days sooner than I told you of, it falling out so that I was to meet a friend then at Newmarket, and so missed of your intended directions; yet I called at your lodgings a day [or] two before I came away, but missed of you. If, therefore, you continue . . . . . . to have it observed, you may, by sending your directions, command . . . . . . your humble servant,