HALLEY, EDM UND, a celebrated astronomer and na tural philosopher, was born at Ilaggerston, in the parish of St Leonards, Shoreditch, London, on the 8th November 1656. His father, who was au opulent citizen and soap boiler, sent him to St Paul's school, where, under the care of the learned Dr Gale, he made rapid advances in his classical studies, and acquired such a taste for elemen tary astronomy, that he amused himself in making dials, and observed the change in the variation of the needle at London in the year 1672, the y ear before he left school. nom this seminary, which he left in 1673, lie went to Queen's College, Oxford, where he was entered a gentle man commoner, and where, with the aid of a good collec tion of instruments which his father had purchased for him, lie devoted himself almost exclusively to the study of ma thematics and astronomy. In the year 1676, lie published his first paper in the Philosophical Transactions, entitled " Direct and Geometrical Method of investigating the Aphelia, the Eccentricities, and the Proportions of the Or bits of the Primary Planets, without supposing the equality of the Angle of Motion at the other focus of the Planet's Ellipsis;" and lie continued to employ himself in astrono mical observations. Although he had long entertained a plan of forming a complete catalogue of the fixed stars, yet he abandoned this scheme upon hearing that Flamstead and llevelius were occupied in the same pursuit. lie resolv ed, however, to form a catalogue of the stars of the south ern hemisphere ; and, by the influence of Joseph \Villain son, Secretary of State, and Sir J. Moore, Surveyor of the Ordinance, Charles II. was prevailed upon to send Halley to St Veleta, elena, in order to accomplish this desii able object. He arrived on the island in February 1677, after a voyage of three months; and though lie was much interrupted by the frequent fogs which hover over it, yet, by the most un industry, he at last executed his plan, •mch he published in 1679, under the title of Catalogus Stellarunz Australium. This work was presented, on his return from St Helena, in November 1678, to Charles II. who gave him a mandamus to the University of Oxford for the de gree of A.M. Halley had rewarded the kindness of his patron by forming a new constellation under the name of Robur Carolinum. _ During his stay at St Helena, he had the good fortune to observe the transit of Mercury over the sun's disc.
In the year 1678, Halley was elected a Fellow of the Royal Society of London ; and, in consequence of the dispute be tween Hevelius and Hooke respecting the use of telescopic sights, he went to Dantzic in 1679, for the purpose of settling the controversy, by examining the method of observation employed by the Polish astronomer. Ile remained at Dant zic from the 26th of May till the 18th July, and returned to England deeply impressed with a conviction of the won derful perfection of Hevelius's instruments, and of the great accuracy of his observations.
In the year 1680, Halley set out for Paris, accompanied by his friend Mr Nelson, with the view of performing the grand tour of Europe. In crossing the English channel, he obtained a view of the great comet upon its return from the sun ; and having been fortunate enough to observe its descent towards that luminary, he was able to complete his observations at the Royal Observatory of Paris, which was then under the direction of Dominique Cassini. From Paris he went to Italy, where he spent the greater part of the year 1681 ; but his private affairs obliged him to return to England about the end of the year.
Soon after his arrival in London, Halley married the daughter of Mr Tooke, auditor of the Exchequer, and took up his residence at Islington, where he put up his astro nomical apparatus, and pursued with ardour his favourite study. 'With this amiable woman Halley lived 55 years, but was not blessed with any family.
In the Philosophical Transactions for 1683, he published his Theory of the Variation of the Magnetical Compass—a paper of singular merit, in which he endeavours to spew, that the " whole globe of the earth is one great magnet, having four magnetical poles or points of attraction, near each pole of the equator two ; and that, in those parts of the world which lie near adjacent to any of these magnetic poles, the needle is governed thereby, the nearest pole be ing. always predominant over the more remote." Our author's studies were now somewhat interrupted by domestic misfortunes. His father had suffered greatly from the fire in London ;. and having imprudently entered into a second marriage, he was reduced comparatively to a state of poverty. His son, however, speedily resumed his usual occupations ; and, in the year 1634, his attention was directed*to the subject of Kepler's sesqnialterate pro portion, from which he concluded that the centripetal force must be invet sely as the square of the distance. He found himself unable, however, to establish this by geometrical principles ; and having applied in vain for assistance to Dr Hooke and Sir C. 'Wren, he at last made a visit to Cam bridge, in order to consult Mr Newton. This illustrious mathematician communicated to Halley 12 theorems which he had written upon the subject, containing his theory of gravitation. Halley was so delighted with the develope mem of this gi'eat discovery, that he prevailed upon New ton to complete his PrinciJiia, which was actually publish ed in 1686, under the immediate care of Dr Halley, who prefixed to it a discourse of his own, and complimented Newton in an elegant copy of •Latin verses.