Dr James, a celebrated English astronomer, was born at Sherborne in Dorsetshire in March 1692. He was educated at a school at North Leach, and at Balliol College, Oxford. As soon as he was of age to receive holy orders, the Bishop of Hereford gave him the vicarage of Bridstow; and he obtained soon afterwards the rectory of Llandewy-Welfric in Pembrokeshire. Both these livings, however, and the hopes of further advancement in the church, he at length resigned, that he might devote himself entirely to mathematics and astronomy.

For a while he was curate of Wanstead in Essex, of which parish his uncle, Mr Pound, favourably known to the learned world for his astronomical observations, was rector. It may be imagined that the example and conversation of Mr Pound did not render Bradley fonder of his profession than before. He still continued, however, to fulfil his duties, though at this time he had made such observations as laid the foundation of those discoveries which afterwards distinguished him as one of the greatest astronomers of his age. These observations, made as it were by stealth, soon gained him the notice and friendship of the Lord Chancellor Maccllesfield, Newton, Halley, and other members of the Royal Society, into which he was soon elected a member. On the death of Dr Keil in 1721, Bradley was appointed to succeed him as Savilian professor of astronomy; and for his colleague he had Halley, who was professor of geometry on the same foundation. Bradley now resigned his two livings, quitting with joy a situation in which his duty was directly at variance with his inclination. From this time he devoted himself wholly to the study of his favourite science; and in 1727 he established his reputation by publishing a Theory of the Aberration of the Fixed Stars, which is allowed to be one of the most useful and ingenious discoveries of modern astronomy. Three years afterwards he was appointed lecturer in astronomy and physics in the university of Oxford. In the course of his observations, he discovered that the inclination of the earth's axis upon the plane of the ecliptic was not always the same, but that it varied backwards and forwards some seconds, and that the period of these variations was nine years. This period seemed altogether unaccountable, as it could not be supposed to have anything in common with the revolution of the earth, which is performed in one year. Bradley, however, discovered the cause of this phenomenon in the Newtonian system of attraction, and published his discovery in 1737; so that in the space of about ten years he communicated to the world two of the finest discoveries in modern astronomy, which will forever form an epoch in the history of that science.

In 1742 he had the honour of succeeding Dr Halley as astronomer-royal. That great man, now worn out with age and infirmities, had intended to resign in favour of Bradley; but while occupied with this friendly project, he died. As soon as Bradley's appointment became known, the university of Oxford created him doctor of divinity. Bradley was now in his proper element, and pursued his observations with unwearied diligence. In 1748 he availed himself of the annual visit made by the Royal Society to the observatory, to represent the necessity of repairing the old instruments and purchasing new ones; and in consequence, a grant of L1000 was made by the king for that purpose. This sum enabled the astronomer-royal to furnish the observatory with as complete a collection of astronomical instruments as this most skilful and diligent observer could then procure.

In 1751 Bradley received an offer of the vacant vicarage of Greenwich, a very considerable living, and conveniently situated for the performance of its duties; but this offer he declined on conscientious grounds. The king, on hearing of the refusal, granted him a pension of L250 a-year, in consideration of his great abilities and knowledge in astronomy and other branches of the mathematics, which had proved so advantageous to the commerce and navigation of Great Britain, as is particularly mentioned in the grant, dated the 15th of February 1752. About the same time he was admitted into the council of the Royal Society, and in 1748 he was elected a member of the Royal Academy of Berlin. In 1752 he was made a member of the Imperial Academy at Petersburg; and in 1757, of that instituted at Bologna.

Till within two years of his death, Bradley continued to be indefatigable in his observations, and every honour he received became an excitement to fresh exertion; and when at last his strength gave way, the vigour of his intellect suffered no abatement. He died, after a painful illness, on the 13th of July 1762. He had married in 1744 Susannah Peach, a lady of Gloucestershire, by whom he had one daughter.

Dr Bradley possessed an amiable disposition and great equanimity of temper. Though a good and clear speaker, he was remarkably silent, never speaking except when he thought he could communicate some useful knowledge. He was not more inclined to write than to speak, and published very little, having had a diffident aversion to attract public notice. Two volumes of his observations were published at Oxford in 1798 and 1805.