EDMUND HALLEY, the second English philosopher of the later day of Newton, was born October 29, 1656, at his father's country-house at Haggerston, near London: Mr. Halley the father was a wealthy soap-boiler in Winchester Street. The son was educated at St. Paul's School, of which he was captain at fifteen years of age. He had then begun to lay the foundation of that store of various knowledge for which he was afterwards so remarkable. At Midsummer, 1673, when, before he was quite seventeen, he was entered at Queen's College, Oxford, he was strong in Latin,

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Greek, and Hebrew, and stronger in mathematics and astronomy: he had discovered for himself the alteration of the variation of the needle, before he found in books that it was already known. In 1676 he commenced his career by publishing in the Philosophical Transactions a direct geometrical method of finding the aphelia and eccentricities of the planets.

The

The father, a tradesman of the old school, supplied his son liberally with astronomical instruments. To understand this, the reader must remember that the London man of business in the sixteenth and first half of the seventeenth centuries was generally a friend of knowledge, and not unfrequently a promoter of it who had learned its value at one of the Universities. The poor creature of the eighteenth century, who is described as asking his son what learning was worth on 'Change, and whether Aristotle ever made cent. per cent., belongs to another race of men, which will soon be quite extinct. schism between learning and commerce seems to have been a consequence of the two revolutions, and of the religious and political animosities to which they led. It is by no means unlikely that IIalley's father was capable of reading and judging of his son's first paper. Be this as it may, the son, thus encouraged by his father, applied himself to the observation of Jupiter and Saturn, and detected, for the first time, that acceleration of the one and retardation of the other, the explanation of which has since been made so strong a confirmation of the theory of gravitation. Desiring to amend the tables of these planets, he soon saw that nothing could be done without better catalogues of stars than then existed and learning that Hevelius and Flamsteed were employed on such work in the northern hemisphere, he fixed on the south as the scene of his own operations. With his father's consent, effectively shown by an allowance of 300l. a year, he chose St. Helena as a proper spot from which to observe; for that island he set sail in November, 1676, still a minor, with a recommendation from the king to the East India Company. His principal instruments were a large sextant, quadrant, and telescope, and a pen

dulum clock. He remained at St. Helena two years, not much pleased with the climate, nor with the disposition of the Governor towards him. He formed * a catalogue of 350 stars, observed a transit of Mercury over the sun, and suggested the use which (in the case of Venus) has since been made of such phenomena in determining the distance of the sun from the earth. He observed also that increase of curvature in the moon's orbit at and near the half moons, which was afterwards explained by Newton as a consequence of gravitation. And, on the voyage out, he discovered the necessity of shortening the pendulum of the clock as the ship approached the equator, which was also afterwards explained by Newton, to whom Halley's observations first conveyed the knowledge of the phenomenon. The catalogue was published in 1679, under the title of Catalogus Stellarum Australium.

Immediately after Halley's return, in November, 1678, he was created Master of Arts (Oxford) by Royal Mandate, and was elected a fellow of the Royal Society. This body immediately dispatched him on a mission to Hevelius, the celebrated astronomer of Dantzig, to examine and report on the mode of observing of the latter. Hevelius would not use the telescope, contending that observations might be better made without it, and challenging inspection. Halley arrived at Dantzig, May 16, 1679, and immediately commenced a course of observations with Hevelius, which he continued till the end of July, when he returned to England, satisfied that his coadjutor's observations were certainly good. Hevelius, in his records of this year, calls him a very pleasant guest, a most honest man, and a sincere lover of truth.

In 1680 and 1681 Halley travelled in France and Italy, partly in company with Nelson, afterwards well known as the author of a work on Feasts and Fasts. At

The reader will remember that forming a catalogue of stars includes the accurate determination of their places in the heavens by repeated observations: and the sextant and quadrant mode of proceeding implies very heavy calculation for each star.

the end of 1681 he married the daughter of Mr. Tooke, Auditor of the Exchequer: with this lady he lived upwards of fifty-five years. From 1682 to 1684 he was engaged at his residence in Islington with the commencement of a series of lunar observations. He intended to continue them for eighteen years, the period of a revolution of the moon's node (which, as we shall see, he afterwards accomplished). But the death of his father, and some legal difficulties in which his property was thereupon involved, obliged him to " postpone all other considerations to the defence of his patrimony." He published many papers at this time and in 1685 and 1686 took that remarkable share in the production of Newton's Principia which we have described in our memoir of Newton. It was while his own affairs were embarrassed by the great fire and suits at law that this miracle of energy (for Halley is nothing less) occupied himself with the question of gravitation, sought for information from Hook, Wren, and Newton, found out what the latter had done, induced him to begin the Principia, interested the Royal Society in its continuance, kept Newton up to his engagement, prevented him from mutilating it in disgust, undertook to see the work through the press, paid the expense of printing, and made himself thoroughly master of its contents, the most difficult task of all.

In 1691 the Savilian Professorship at Oxford became vacant, and Bishop Stillingfleet was requested to recommend Halley. Whiston informs us he had it from Dr. Bentley, that the bishop, hearing that Halley was not a believer in Christianity, desired to be excused until his Chaplain (who was Bentley himself) should have talked with the reputed infidel. In the conversation which thereupon took place, Halley "would not so much as pretend" to believe, and the appointment was elsewhere given. We shall presently see that some counter-evidence has been offered on this point. In 1696, the same year in which Newton was appointed to the Mint in London, Halley was appointed Comptroller of that at Chester. At the end of two years he applied to King William for

means to pursue his magnetical observations. The request was granted; he was appointed a Captain in the Navy, and the command of the Paramount, one of the class of vessels called Pinks, was given to him. He set out in November of that year, and had crossed the Line, when he was induced to return, by finding that his crew were little inclined to obey him, and that his First Lieutenant was himself a mutineer. At his return, this officer was dismissed the service; and Halley set out again in September, 1699, no longer Captain only, but Commodore, with two ships under his command. He now traversed the Atlantic, touching at the Brazils, the West Indies, St. Helena, &c., and collected materials for the chart of magnetic variations, which he published on his return. In 1701 he sailed again to survey the British Channel, of which he published a chart. He was then sent to the Adriatic, to assist in the formation of harbours in the Emperor's dominions; and on his return in November, 1703, threw off his epaulettes and put on his gown again, being appointed Savilian Professor of Geometry at Oxford. It is not known that anything was said this time about his religious opinions. In his capacity as Professor, he edited a splendid edition of the Conic Sections of Apollonius, in 1710. More than this, he deciphered and published, from an Arabic manuscript, a translation of the work of Apollonius De Sectione Rationis. Not that he understood a word of Arabic, but he had a few pages which had been translated by Dr. Bernard, which he used, with the diagrams, as a key to the rest. And Dr. Sykes, the Professor of Hebrew, assures us that Halley brought to him emendations of this Arabic text, pointing out what was said, and what ought to have been said, and what Dr. Sykes found might have been said with much slighter alteration than Halley could have supposed.

Halley became resident in town again some years before 1713, for he was largely mixed up with Newton in the proceedings against Flamsteed, and was a member of the Committee which drew up the Commercium Epistolicium, in the dispute with Leibnitz (see our memoir