as a chorister or servitor, and proceeded M.A. on 28 Sept. 1663, on the nomination of Lord Clarendon, chancellor of the university. His mechanical skill brought him to the notice of a concourse of learned men at Oxford in 1655; he communicated his artifices for flying to John Wilkins [q. v.], then warden of Wadham College, studied astronomy by the advice of Seth Ward [q. v.], assisted Thomas Willis [q. v.] in his chemistry, and was by him recommended to the Hon. Robert Boyle [q. v.], whom he materially aided in the construction of his air-pump. Hooke is said by Wood to have also ‘read to him Euclid's “Elements,” and made him to understand Descartes.’ A small tract on capillary attraction, published by Hooke in 1661 (included in his Micrographia, p. 10), won attention from the Royal Society, and on 12 Nov. 1662 he was appointed their curator of experiments, when Boyle was thanked for dispensing with his services (Birch, Hist. Royal Society, i. 124). His election as fellow on 3 June 1663 carried with it exemption from all charges (ib. i. 250); he was frequently a member of the council, and the society's repository was committed to his care on 19 Oct. 1663. In June 1664 Sir John Cutler [q. v.] founded, for Hooke's benefit, a lecture of 50l. a year, leaving the number and subjects of his discourses to the discretion of the Royal Society (ib. i. 484); and his office of curator was, on 11 Jan. 1665, made perpetual, with a salary of 30l. and apartments in Gresham College, Bishopsgate Street, where he resided during the remainder of his life. His nomination as professor of geometry in Gresham College followed on 20 March 1665, and he read astronomical lectures in the same institution as locum tenens for Dr. Pope in 1664–5.
The registers of the Royal Society testify to the eagerness with which Hooke hurried from one inquiry to another with brilliant but inconclusive results. Among those which early engaged his attention were the nature of the air, its function in respiration and combustion, specific weights, the laws of falling bodies, the improvement of land-carriage and diving-bells, methods of telegraphy, and the relation of barometrical readings to changes in the weather. He measured the vibrations of a pendulum two hundred feet long attached to the steeple of St. Paul's; invented a useful machine for cutting the teeth of watch-wheels; fixed the thermometrical zero at the freezing-point of water; and ascertained (in July 1664) the number of vibrations corresponding to musical notes. This he explained on 8 Aug. 1666 to Pepys, who thought his ‘discourse in general mighty fine,’ but his pretension ‘to tell how many strokes a fly makes with her wings’ ‘a little too much refined’ (Diary, iv. 43, Bright's ed.) In 1665 was published his ‘Micrographia, or some Physiological Descriptions of Minute Bodies,’ a book full of ingenious ideas and singular anticipations. It contained the earliest investigation of the ‘fantastical colours’ of thin plates, with a quasi-explanation by interference (p. 66), the first notice of the ‘black spot’ in soap-bubbles, and a theory of light, as ‘a very short vibrative motion’ transverse to straight lines of propagation through a ‘homogeneous medium.’ Heat was defined as ‘a property of a body arising from the motion or agitation of its parts’ (p. 37), and the real nature of combustion was pointed out (p. 103) in detail, eleven years before the publication of Mayow's similar discovery (see Nicholson, Journal, iii. 497; Robison's Note 13 to Black's Elements of Chemistry, i. 535).
While the plague raged in London, Hooke was employed as philosophical assistant by Dr. Wilkins and Sir William Petty, at Durdans, the seat of the Earl of Berkeley, near Epsom; and the meetings of the Royal Society having been resumed, he read, on 21 March 1666, a discourse on gravity, containing the happy idea of measuring its force by the swinging of a pendulum. This was followed, after two months, by a paper on curvilinear motion, illustrated with the aid of the ‘circular pendulum,’ an unacknowledged loan from Horrocks (Birch, Hist. Royal Society, ii. 90; Grant, Hist. of Astronomy, p. 425). By this means Hooke showed experimentally that the centre of gravity of the earth and moon is the point describing an ellipse round the sun. The clear statement of the planetary movements as a problem in mechanics dates from this remarkable essay. About this time Hooke presented to the Royal Society the first screw-divided quadrant, an anemometer (described in Phil. Trans. ii. 444), of a form lately recommended for universal use by Professor Wild (Scott, Meteorology, p. 150), and a ‘weather-clock.’ He applied the circular pendulum to watches (Birch, Hist. Royal Society, ii. 97), experimented upon himself in an exhausted receiver, and on 12 June 1667 discoursed on the effects of earthquakes. On 19 Sept. 1667 he exhibited a model for rebuilding the city after the great fire, which, though not adopted, procured him the appointment of city surveyor. In this lucrative employment he accumulated some thousands of pounds, found after his death in an iron chest, unopened for thirty years. Among the buildings designed by him were the new Bethlehem Hospital, Montague House, and the College of Phy-
