BRADLEY (Du. JAMES,) a celebrated English astronomer, the third son of Wil liam Bradley, was born at Sherborne, in Gloucestershire, in the year 1692. He went to Oxford, and was admitted a com moner of Baliol College, March 15, 1710, where he took the degree of bachelor the 14th of October, 1714, and of master of arts the 21st of January, 1716. His friends intending him for the church, his studies were regulated with that view ; and as soon as he was of a proper age to receive holy orders, the Bishop of Here ford, who had conceived a great esteem for him, gave him the living of Briclstow, and soon after he was inducted to that of Landewy Welfry, in Pembrokeshire.
He was nephew to Mr. Pound, a gen tleman well known in the learned world, by many excellentastronomical and other observations, and who would have enrich ed it much more, if the journals of his voyages had not been burnt at Polu Con dor, when the place was set on fire, and the English who were settled there cru elly massacred, Mr. Pound, himself, very narrowly escaping with his life. With this gentleman,at Wan ste ad, Mr. Bradley, passed all the time that he could spare from the duties of his function ; being then sufficiently acquainted with the ma. thematics to improve by Mr. Pound's con versation. It may easily be imagined that the example and conversation of this gentleman did not render Bradley more fond of his profession, to which he bad before no great attachment; he continued, however, as yet to fulfil the duties of it, though at this time he had made such observations, as laid the foundation of those discoveries which afterwards dis tinguished him as one of the greatest as tronomers of his age. These observa tions gained him the notice and friendship of the Lord Chancellor Macclesfield, Mr. Newton, afterwards Sir Isaac, Mr. Halley, and of many other members of the Royal Society, into which he was soon after elected a member.
Soon after, the chair of Savilian pro fessor of astronomy at Oxford became vacant, by the death of the celebrated Dr. John Keil, and Mr. Bradley was elected to succeed him on the 31st of October, 1721, at 29 years of age, his colleague being Mr. Halley, who was professor of
geometry on the same foundation. Upon this appointment, Mr. Bradley resigned his church livings, and applied himself wholly to the study of his favourite sci ence. In the course of his observations, which were almost innumerable, he disco veredand settled the laws of theaberration of the fixed stars, from the progressive mo tion of light, combined with the earth's, annual motion about the sun, and the nota tion of the earth'saxis,arising from the un equal attraction of the sun and moon on the different parts of the earth. The former of these effects is called the " aberration" of the fixed stars, the theo ry of which he published in 1727 ? and the latter, the " notation" of the earth's axis, the theory of which appeared in 1737 : so that, in the space of about ten years, he communicated to the world two of the finest discoveries in modern astro nomy, which will for ever make a memo rable epoch in the history of that science. See ABERRATION and NUTATION.
In 1730, Mr. Bradley succeeded Mr, Whiteside, as lecturer in astronomy and experimental philosophy in the Museum at Oxford, which was a considerable emolument to him, and which he held till within a year or two of his death, when his ill state of health induced him to re sign it. He always preserved the esteem and friendship of Dr. Halley, who, be ing worn out by age and infirmities, thought he could not do better for the service of astronomy, than procure for Mr. Bradley the place of regius professor of astronomy at Greenwich, which he himself had many years possessed with the greatest reputation. With this view he wrote many letters, desiring Mr. Brad ley's permission to apply for a grant of the reversion of it to him, and even of fered to resign it in his favour, if it should be thought necessary ; but Dr. died before he could accomplish this kind object. Dr. Bradley, however, obtained the place in February, 1741-2, by the in terest of Lord Macclesfield, who was af terward president of the Royal Society, and upon his appointment the University of Oxford sent him a diploma of doctor of divinity.