Newton, Sir Isaac 1642 -1727.

Newton was born in the manor house at Woolsthorpe, eight miles south of Grantham, Lincolnshire on 25th December 1642. Newton's father died at the age of 36, in October 1942, before the birth of his son. His mother then married Barnabas Smith, Rector of North Witham, Lincolnshire who died in 1656. On his mother's second marriage Newton was left at Woolsthorpe in the charge of his grandmother, Mrs Ayscough. He was sent in 1654 to the grammar school at Grantham kept by Mr Stokes.

Newton made little advance in his education but after a fight with an older boy he grew keener and soon rose to be head of the school. At the age of 14 his mother returned to Woolsthorpe on the death of her second husband. She took over the management of her farm, and removed young Newton from the school. On the advice of his uncle he was sent back to school in 1660, and on the 5th June 1661, Isaac was matriculated at Trinity College Cambridge under Mr Pulleyne.

In 1664 Newton made some observations on halos afterwards described in his "optics". He graduated B.A. in January 16th, 1665. His unrivalled genius for mathematical speculation showed in boyhood. Before coming to Cambridge he had read Sanderson's "logic" and Kepler's "optics". As an undergraduate he applied himself to Déscartes' "Geometry" and Wallis's "Arithmetica Infinitorum". He attended Barrow's lectures. His mental activity immediately after taking his degree during 1665 and 1666 was extraordinary. He found the method for approximating series and the rule for reducing the power of any binomial to a series. This was his binomial theorum. In May he found the method of tangents of Gregory and Slusius. In the November he produced the direct method of “fluxions” (ie. the elements of the differential calculus). In the next year in January he wrote on theory of colours. In the following May he started work on integral calculus. In the same year he began to think of gravity extending to the Orb of the Moon. Newton was driven from Cambridge by the plague in 1665, and in that autumn "he fell into a speculation that the power of gravity is not found sensibly diminished at the remotest distance from the centre of the earth from which we can rise”. It appeared reasonable to him that this power must extend much further than is usually thought. Why not as far as the moon? If so the motion must be influenced by it –“perhaps she is retained in her orbit thereby”. Voltaire, who was told about this by Newton’s step-niece, Mrs. Conduit, popularised the story that this train of thought was caused by an apple. Newton at this time by a simple deduction from Kepler's third law, proposed that if the Moon were kept in an orbit approximately circular by a force directed to the centre of the earth, then that force must be inversely proportional to the square of the distance between the Moon and the earth. He proceeded therefore to compare the consequences of his theory with the observed motion of the Moon and found them to answer pretty nearly. Still the matter was laid aside and nothing more came of it for nearly 20 years. To make the calculation, knowledge of the Earth's radius was required. The common estimate in use among geographers before Newton’s time was based on the supposition that there were 60 miles to a degree of latitude and Newton took this common estimate but added "as this is a very faulty supposition, each degree containing about 69 and a half miles" his computation did not fit, and he concluded that some other cause must at least join with the power of gravity on the Moon.

Newton was elected a Fellow of the Royal Society in 1672. He was unable to calculate the attraction of a large spherical body on a point near its surface until about 1685. It was in his "Principia" that Newton first publicly divulged the solution of that problem. He was elected a Fellow of Trinity College in 1667. During the next few years he turned his attention to his optical work and made his first reflecting telescope in 1668. It had an aperture of about one inch and was six inches long. With it he saw Jupiter's satellites.

At the end of 1668 Mercator had shown how to calculate the area of a hyperbola. A copy of this was sent by John Collins to Barrow, and shown by him to Newton. Newton recognised that the method was mainly the same as the more general one he had already devised for finding the area of curved surfaces and for solving other problems. Newton was chosen in 1669 to succeed Barrow in the Lucasian chair at Cambridge. He was led to conclude from his optical experiments that it was impossible to perfect the refracting telescope and he applied himself to improving his reflecting instrument. Towards the end of the same year, 1671 he was busy enlarging his method of infinite series. He was proposed for election as a Fellow of the Royal Society in 1672. He wrote afterwards an account of the experiments with the prism bought in 1666 to try to explain the phenomena of colours. The experiment had shown conclusively "that light consists of rays differently refrangible - that colours are not qualifications of light derived from refractions of natural bodies as was generally believed but original and connate properties in which divers rays are diverse that to the same degree of refrangability ever belongs to the same colour. The white light is never compounded and to its composition are requisite all the primary colours mixed in proper proportion". On this Hooke alone appears to have reported and his report was read at the next meeting. Hooke in the discussions about the telescope had already appeared as a critic of Newton. Déscartes had in 1637 described the rainbow colours produced by refraction of light banded by shade through a prism and had elaborated a theory of colours. This theory was adopted by with modifications in 1664 by Hooke, who described an experiment practically identical with that of Newton's experiment with the prism. See the Dictionary of National Biography, 1893.

[1] Robert Hooke (1635 - 1703) postulated before Newton the theory of universal gravitation, but was unable to express it mathematically. He did moreover state the inverse square law and related this to the path of projectiles. He quarrelled constantly with Newton on the basis of who introduced these ideas first. He had made many inventions including an odometer; a hearing aid; a reflecting Quadrant; a system of telegraphy; a barometer; the universal joint; an anchor escapement for clocks and an arithmetical machine (calculator). He produced the Gregorian telescope and a theory of the variation of the compass. He explained the scintillation of the stars by irregular atmospheric retractions and inferred the solar repellent force in producing the tails of comets. He suggested the motion of the sun amongst the stars and propounded correct notions as to the nature of fossils and the succession of living things upon the earth (preceding Darwin). He also invented a marine barometer. One of his posthumous works was a hypothesis of the cause of gravity found in any propagated pulse of the ether (dark matter). See Dictionary of National Biography, 1893