‘To conclude, all his Errors and Blemishes were more than made amends for, by the Greatness and Extent of his natural and acquired Parts, and more than common, if not wonderful Sagacity, in diving into the most hidden Secrets of Nature, and in contriving proper Methods of forcing her to confess the Truth, by driving and pursuing the Proteus thro’ all her Changes, to her last and utmost Recesses…
There needs no other Proof for this than the great number of Experiments he made, with the Contrivances for them, amounting to some hundreds; his new and useful Instruments and Inventions, which were numerous, his admirable Facility and Clearness, in explaining the Phaenomena of Nature, and demonstrating his Assertions; his happy Talent in adapting Theories to the Phaenomena observ’d, and contriving easy and plain, not pompous and amusing Experiments to back and prove those Theories; proceeding from Observations to Theories, and from Theories to farther trials, which he often asserted to be the most proper method to succeed in the interpretation of Nature. For these, his happy Qualifications, he was much respected by the most learned Philosophers both at home and abroad: And as with all his Failures, he may be reckon’d among the great Men of the last Age, so had he been free from them, possibly, he might have stood in the Front. But humanum est errare.’
Richard Waller’s Life of Hooke, The Posthumous Works of Robert Hooke (London, 1705).
Robert Hooke (1635-1703) might have reflected, had he been in a position to read Waller’s edition of his Works, that with biographers like this, he didn’t need enemies. Given that Waller was writing in 1705 at the behest of the Royal Society, Hooke’s quarrels with Newton are lightly glossed over (compared to Hooke’s debate with Johannes Hevelius). The initial dispute over Newton’s theory of light and colours is treated in one diplomatic sentence: ‘This same Year  several Discourses and Papers past between the Learned Mr Newton and Mr Hooke concerning a new Theory of Light and Colours, which being now so generally known, I shall not farther insist on.’ The gravity dispute is quietly ignored, Waller excusing himself by saying that from 1682 onwards Hooke ‘began to be more reserv’d than he had been formerly, so that altho’ he often made Experiments, and shew’d new Instruments and Inventions, and read his Cutlerian Lectures, yet he seldom left any full Account of them to be enter’d, designing, as he said, to fit himself for the Press, and then make them publick, which he never perform’d. This is the reason that I am oblig’d to be the shorter in the remaining part of his Life; and shall only touch upon some few of his Performances, since the bare meaning of them, or mentioning their Titles, will but create an uneasy Curiosity in the Reader without any satisfaction.’ Here we see yet again the influence of Newton as President of the Royal Society (to whom the book was dedicated).
Richard Waller’s life of Robert Hooke in his edition of The Posthumous Works (1705), coupled with the subject matter of the book, does, however, reflect the two sides of Hooke: his avid interest in experiments of all kinds and his often contentious interactions with other natural philosophers. The breadth of Hooke’s interests is awe inspiring but it had an unlooked for effect: all too often Hooke outlined a proposed plan of research but did not carry it through. It was this tendency which was at the heart of the gravity dispute (and indeed Hooke’s dispute with other scientists).
Hooke and Newton’s initial debate in 1672 was concerned with light. Newton, a young academic, had sent his paper on light and colours to the Royal Society. Hooke’s private response was to reject Newton’s theory – a reaction which galvanized Newton to write a public rebuttal which was published in the Philosophical Transactions. Three years later, when Newton’s second paper on colours was published, Hooke’s response was more muted and favourable, though it is clear that the initial dispute continued to rankle with both men. Hooke’s attempt to heal the breach in 1679 later led to an unforeseen effect: a bitter dispute over who had discovered universal gravity.
On the one hand, Hooke could point to his 1664 Cutlerian lecture (published in 1679), which had considered gravity in the following terms:
‘First, That all Celestial Bodies whatsoever, have an attraction or gravitating power towards their own Centers, whereby they attract not only their own parts, and keep them from flying from them, as we may observe the earth to do, but that they do also attract all the other Coelestial Bodies that are within the sphere of their activity… The second supposition is this, That all bodies whatsoever that are put into a direct and simple motion, will so continue to move forward in a straight line, till they are by some other effectual powers deflected and bent into a Motion, describing a Circle, Ellipsis, or some other more compounded Curve Line. The third supposition is, That these attractive powers are so much the most powerful in operating, by how much the nearer the body wrought upon is to their own Centers.’
However, as Westfall (1967) argues, Hooke’s conception of gravity in this lecture talks about particular gravities. Newton, via his editor Roger Cotes later admitted in the second edition of the Principia in 1713 ‘that the force of gravity is in all bodies universally others have suspected or imagined’, but, as Cotes continued to explain, ‘Newton was the first and only one who was able to demonstrate it from phenomena and to make it a solid foundation for his brilliant theories.’ In other words, Hooke might have bright ideas but was unable to progress them, a view encapsulated in Newton’s 1686 letter to Halley concerning the inverse square rule, that ‘Mr Hook, without knowing what I have found since his letters to me, can know no more than the proportion was duplicate quam proximé at great distance from the center, & only guessed it to be so accurately, & guess amiss in extending that proportion down to the very center’. More recent assessments disagree with this view and point to Hooke’s 1685 work (unpublished at the time) which, Nauenberg (2005) argues, includes ‘a geometrical implementation of orbital motion for central force motion’.
In his dispute with Newton, Hooke concentrated on the inverse square law, arguing that Newton owed the idea to his correspondence with Hooke. He was unaware that Newton has already formulated it as an idea. Where Hooke did make his mark was in encouraging Newton to think about orbital motion in a different way. Hooke’s use of the word ‘centripetal’ rather than centrifugal was certainly new. As Westfall (1967) reminds us, ‘Without the concept of centripetal force, the theory of universal gravitation was inconceivable, and Hooke’s contribution to gravitation was not then insignificant’. Even this comment does not perhaps do justice to Hooke. Comparisons with Newton were bound to be odious and drew attention away from Hooke’s very real achievements: his mechanical inventions; the role his many experiments played in keeping life in the Royal Society during difficult times; his architectural initiatives; and, last but not least, his fascinating Micrographia which Westfall (1972) rightly calls ‘one of the masterpieces of seventeenth-century science’. Worth characteristically owned a copy.
Feingold, Mordechai (2004), The Newtonian Moment. Isaac Newton and the Making of Modern Culture (New York and Oxford).
Gal, Ofer (2005), ‘The Invention of Celestial Motion’, Early Science and Medicine, vol. 10, no. 4., pp. 529-534.
Guicciardini, Niccolò (2005), ‘Reconsidering the Hooke-Newton Debate on Gravitation: Recent Results’, Early Science and Medicine, vol. 10, no. 4., pp. 510-517.
Nauenberg, Michael (2005), ‘Hooke’s and Newton’s Contribution to the Early Development of Orbital Dynamics and the Theory of Universal Gravitation’, Early Science and Medicine, vol. 10, no. 4., pp. 518-528.
Pugliese, Patri J. (2004), ‘Hooke, Robert (1635–1703)’, Oxford Dictionary of National Biography, Oxford University Press.
Westfall, Richard S. (1967), ‘Hooke and the Law of Universal Gravitation: A Reappraisal of a Reappraisal’ The British Journal for the History of Science, vol. 3, no. 3m pp. 245-61.
Westfall, Richard S. (1972), ‘Hooke, Robert’, Dictionary of Scientific Biography (New York), vol VI, pp. 481-8.
Westfall, Richard S. (2004), ‘Newton, Sir Isaac (1642–1727)’, Oxford Dictionary of National Biography, Oxford University Press.