published anything of himself, and we may be certain that but for Halley the “Principia” would not have existed. He was the original cause of its being undertaken, and when, in consequence of Hooke's unfair claims, Newton would have suppressed the third book, it was his explanations and entreaties that smoothed over the difficulty and induced Newton to change his mind. He paid all the expenses, he corrected the proofs, he laid aside his own work in order to press forward to the utmost the printing, lest anything should arise to prevent the publication. All his letters show the most intense devotion to the work; he could not have been more zealous had it been his own’ (Glaisher).
After the publication of the ‘Principia,’ Newton took an active part in public affairs. In 1687 James II wished to force the university to confer the degree of M.A. on Alban Francis, a Benedictine monk, without the usual oaths. Newton, with the vice-chancellor and seven other delegates, attended before the ecclesiastical commission to represent the case for the university on 11 April. The vice-chancellor was deprived of his office and dignities, the other delegates sent home with the advice from Judge Jeffreys, ‘Go! and sin no more, lest a worse thing come unto you’ (Macaulay, History, chap. viii.). In 1689 Newton was elected as a whig to represent the university in the Convention parliament. His chief work at this time seems to have been in persuading the university to accept the new government (Thirteen Letters to Dr. Covel, printed by Dawson Turner, 1848). He also became acquainted with John Locke. His friends at this time contemplated his appointment to the provostship of King's College; but this was found to be unstatutable, and rather later, 1691, he was spoken of as a candidate for the post of master of the Charterhouse. His correspondence with Locke about this period (Lord King, Life of Locke) deals with some of his theological speculations. Dr. Edleston has printed (Cotes Corr. p. 273) an interesting paper from Newton to Bentley, who was then preparing the first Boyle lectures, giving directions as to the preliminary reading necessary to understand the ‘Principia.’ ‘At the first perusal of my book it is enough if you understand the Propositions, with some of the Demonstrations which are easier than the rest. For when you understand the easier, they will afterwards give you light unto the harder.’ Some letters to Flamsteed show that he was still working at the lunar theory, and in 1692 he drew up for Wallis two letters on fluxions (printed in Wallis's Works, ii. 391–396), being the first account of the new calculus, now twenty-six years old, published by himself. Next year, 1693, there was some correspondence with Leibnitz on fluxions (Raphson, History of Fluxions, p. 119; Edleston, Cotes Corr. p. 276).
In 1693, Newton, as his letters at this time show, was in a very bad state of health (Brewster, Life of Newton, ii. 85, 132, &c.). A very exaggerated account of his illness was conveyed to Huyghens by a Scotsman named Colin, and was published by M. Biot in his life of Newton in the ‘Biographie Universelle’ (Edleston, Cotes Corr. App. p. lxi). Another story commonly referred to this period is that on coming from chapel one morning he found a number of his papers had been burned by a candle which he had left lighted on the table. Edleston and Brewster both assign this to an earlier date.
Throughout 1694 and 1695 Newton was very actively engaged in elaborating his lunar theory, and he held a long correspondence with Flamsteed relative to observations which he needed to complete that theory (Baily, Life of Flamsteed, pp. 133–60; Edleston, Cotes Correspondence with Newton, n. 118 p. lxiv; Brewster, Life of Newton, ii. 115). The value and importance of his work on the subject have only recently been made known by Professor Adams's labours in connection with the Portsmouth collection. In a scholium in the second edition of the ‘Principia’ Newton states many of the principal results of the theory. The Portsmouth MSS. contain many of his calculations on the inequalities described in the scholium, and also a long list of propositions which were evidently intended to be used in a second edition, upon which it seems that Newton was engaged in 1694 (Cat. of Newton MSS. Pref. pp. xii, xiiii, App. p. xxiii). Another paper of probably the same date, printed for the first time in the appendix to the preface of the ‘Catalogue,’ deals with the problem of the solid of least resistance. In the ‘Principia’ he gives the solution without explaining how he obtained it. The paper in question is a letter to an Oxford friend, probably David Gregory, in which the principles employed are explained.
In a letter to Flamsteed, written in December 1694, Newton endeavoured to explain the foundations of his theory of atmospheric refraction, and a table of refractions by Newton was inserted by Halley in the ‘Philosophical Transactions’ for 1721. It was not known how this table was arrived at, but among the Portsmouth papers are the calculations for certain altitudes, and the method is explained: ‘The papers show that the well-known approximate formula for refraction commonly known as Bradley's was really due to Newton’ (ib. Pref. p. xv).
