VOL. I.] PHILOSOPHICAL TRANSACTIONS. f 



A spot in one of the Belts of Jupiter. By Mr. Hook. 



N^l.p.S. 



The ingenious Mr. Hook * did, some months since, intimate to a friend of 

 his, that he had, with an excellent twelve-foot telescope, observed, some days 

 before he then spoke of it, (viz. on the 9th of May 1(564, about nine o'clock 

 at night) a small spot in the largest of the three obscurer belts of Jupiter; 

 and that, observing it from time to time, he found, that within two hours after, 

 the said spot had moved from east to west, about half the length of the diameter 

 of Jupiter. 



The Motion of the Comet Anno 1664, predicted by M. Auzout.'\ 



N" 1, p. 3. 



The motion of comets was hitherto thought so irregular, as not to be reduci- 

 ble to any laws, and astronomers had always contented themselves with observing 

 exactly the places through which they passed, and where they ceased to appear; 



* Mr. Robert Hook who became celebrated as a philosopher and mathematician, was bom in 1^35 

 in the Isle of Wight. Having a natural taste for painting, he became the pupil of Sir Peter Lely, 

 but soon quitted this pursuit, the oil-colours being injurious to his health. He was then placed under 

 the tuition of Dr. Busby, from whom he acquired a knowledge of the languages. About the year 

 1653 he went to Christ-church, Oxford, and became a member of the philosophical society of 

 learned men then associating in that university. He there assisted Dr. Willis in his chemical 

 operations; and afterwards became assistant to Mr. Boyle. In 1662 he was appointed curator 

 of experiments to the Royal Society, and in l664 professor of mechanics to that learned bodyj 

 at the same time he was also elected professor of geometry in Gresham college. After the 

 fire of London he produced a plan of his own for rebuilding the city, which procured him the 

 appointment of one of the city surveyors, though his plan was not carried into effect. In 1 668 

 he had a dispute with Hevelius respecting telescopic sights, which he supported with such warmth 

 as to give great offence to his scientific friends. In 1671 he attacked Sir Isaac Newton's 

 Theoiy of Light and Colours; and when that philosopher's Principia came out. Hook pretended 

 that the discovery concerning the force and action of gravity was his own, which occasioned 

 tliat patient man to feel some just resentment against him. In 1677 he succeeded Mr. Oldenburg as 

 secretary to the Royal Society. In 1691 archbishop Tillotson created him M. D. by warrant. He 

 died in 1702. Mr. Hook was author of several valuable works, besides many curious papers in the 

 Phil. Trans. A posthumous vol. of his writings appeared in folio, 1705. He was a man of great 

 mechanical genius, and the sciences are highly indebted to him for several valuable instruments and 

 improvements. It is said he was rather deformed in his person^ of a penurious disposition, and ex- 

 tremely jealous of his reputation as an original discoverer. 



f M. Adrian Auzout, a French mathematician and astronomer, of some reputation, was born at 

 Rouen, and died in 1691. It is said he invented tlie micrometer; and wrote a treatise on that in- 

 strument, published in l693. It is also said he was the first person who applied the telescope tp 

 astronomical quadrants, 



A 2 



