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Newton and Astronomers

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Newton and Astronomers:

David Gregory (1659-1708) was undoubtedly one of the most committed of Newton’s followers. The son of David Gregory (1627-1720), an inventor and laird of Kinnairdie (near Aberdeen) he had been educated at Marischal College in Aberdeen and had moved to Edinburgh in the mid 1670s. His uncle, James Gregory (1638-75), had been Professor of Mathematics at the University of St Andrews and had evidently been in contact with Newton. The younger David Gregory decided to follow in his uncle’s footsteps and in 1684 produced his first book, Exercitatio geometrica de dimensione figurarum which, as a form of mathematical homage, utilised material from his uncle and Newton. Gregory was quick to send a copy to Newton, with an accompanying letter stating his great regard. It was to be the start of a fruitful academic friendship for both men. In September 1687, shortly after receiving his copy of the Principia Gregory began a detailed commentary on the work and he was an active member of the group of Scottish Newtonians who helped spread Newtonian ideas not only in Scotland but also in England and the Netherlands. Prior to his election to the Savilian Chair of Astronomy at Oxford in 1691 he had been Professor of Mathematics at the University of Edinburgh and had clearly been unofficially teaching Newtonian ideas to a small number of students there. As Eagles (1977) reminds us, the teaching was unofficial because, as yet, the Principia was not officially on the curriculum and the group was small because the utilitarian nature of the Scottish curriculum make it difficult to incorporate a text like the Principia into it. Despite this, Newtonian ideas were certainly being debated in later seventeenth century Edinburgh: in 1688, a year after the publication of the Principia, Alexander Cockburn examined Newton’s theory of gravity in his graduation these (albeit to disagree with it), and David Gregory’s brother James certainly published a number of graduation theses which were based on the Principia. Despite this, incorporation of Newtonian concepts into the lecture courses at Edinburgh had to wait until the late 1690s-early 1700s.

Astronomiæ physicæ & geometricæ elementa (Oxford, 1702), titlepage.Newtonian Astronomy

Gregory had left the University of Edinburgh by 1691. The defeat of the Stuarts and the rise to political power of presbyterians, coupled with an ensuing visitation of the University of Edinburgh in July 1690, had made Edinburgh an unwelcome place for someone with Gregory’s sympathies. Indeed, Gregory only just managed to hold on to his professorship by swearing an oath of loyalty to the new regime. When Edward Bernard (1638-97) resigned the Savilian Chair of Astronomy at Oxford it must have seemed like a Godsend to Gregory who immediately sought to obtain Newton’s support for his nomination. In this he was successful. Gregory’s comments in his inaugural lecture as Savilian Professor at Oxford may be seen in the ‘Newtonian Astronomy’ webpage of the ‘Astronomy at the Worth Library’ exhibition and do not need repetition here. They plainly show his deep intellectual debt to Newton – as does Gregory’s note on his inaugural speech (quoted by Guerrini (1986)) indicating that he had sought Newton’s advice on his speech: ‘In Mr Newtons opinion a good design of a publick speech (and which may serve well at ane Act) may be to shew that the most simple laws of nature are observed in the structure of a good part of the Universe, that the philosophy ought ther to begin, and that Cosmical Qualities are as much easier as they are more Universall than particular ones, and the general contrivance simpler than that of Animals plants etc.’

Gregory was admitted to Balliol College in 1692, took his doctorate there, and quickly settled into the Oxford academic scene. It was there he published his Astronomiae physicae et geometricae elementa in 1702, which was collected by Worth. In his preface, Gregory explain that his ‘design in publishing this Book, [was] that the Celestial Physics, which the most sagacious Kepler had got the scent of, but the Prince of Geometers Sir Isaac Newton, brought to such a pitch as surprises all the World, might, by my care and pains in illustrating, become easier to such as are desirous of being acquainted with Philosophy.’ It proved to be such a popular exposition of Newtonian astronomy that it led to an English translation in 1715. In this the publishers explained their decision to issue the translation – it was because Gregory’s text was ‘generally reckon’d to be a Book that contains not only all the Discoveries and Philosophical Sentiments of the great Kepler, and the various Hypotheses of the most noted Astronomers before and since his Time;’ but also because it was ‘chiefly valued by the best Judges, for the large and instructive Comments deliver’d in it, on the Writings of the illustrious Sir Isaac Newton…’

Introductio ad veram physicam (Oxford, 1705), titlepage.

A number of Gregory’s Edinburgh students followed him to Oxford, among whom was John Keill (1671–1721), who took his M.A. from Balliol and who would become Savilian Professor of Astronomy in 1712. Though trained as a physician Keill’s interest lay in physics. The book collected by Worth was his Introductio ad veram physicam (Oxford, 1705) which were, in fact, the lectures Keill had give at Hart Hall, following his appointment as lecturer in experimental philosophy. In the main, these were mathematical rather than experimental in nature but they served to influence one of his students who would later become one of the most famous Newtonians, John Theophilus Desaguliers (1683–1744).

In later years Keill proved to be a staunch defender of Newton: he played an important role in the Newton-Leibniz dispute and also sought to defend the Principia against the criticisms of Johann Bernoulli. His involvement in these disputes earned him the reputation as a Newtonian protagonist, ever eager to defend Newton’s works against Leibnizians and, if need be, against fellow Newtonians. Unlike his mentor Gregory, or many of the early Newtonian physicians emanating from Scotland, John Keill was a High Churchman, anxious to prove that Newton was not a heterodox threat to society. His view of Newton’s legacy therefore wildly diverged from that of other Newtonians, especially that of the anti-Trinitarian theologian William Whiston (1667–1752) whose allegiance to the Newtonian cause had done so much to undermine it. Keill’s criticism of Whiston’s use of Newton’s theory of comets in his attempt to explain creation via the mechanical philosophy reminds us that Newtonianism meant different things to different people. It was often easier to define Newtonians by what they were opposed to than to find a common denominator beyond an enhanced respect for the man himself.


Eagles, Christina M. (1977), ‘David Gregory and Newtonian Science’, The British Journal for the History of Science 10, no. 3, pp. 216-225.

Friesen, John (2003), ‘Archibald Pitcairne, David Gregory and the Scottish origins of English Tory Newtonianism’, History of Science xli, pp. 163-191.

Guerrini, Anita (1986), ‘The Tory Newtonians: Gregory, Pitcairne, and Their Circle’, Journal of British Studies 25, no. 3, pp. 288-311.

Henry, John (2004), ‘Keill, John (1671–1721)’, Oxford Dictionary of National Biography, Oxford University Press.

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