File:James Bradley RMG L7803.tiff

A portrait of James Bradley, 3rd Astronomer Royal, 1742-62, in contemporary carved pinewood frame, showing the sitter half-length to the right in clerical robes wearing a wig. The frame has carved floral spandrels, foliate scroll work and is surmounted by carved trophy finial emblematic of science and the arts. Bradley studied theology at Ballol College, Oxford between 1711 and 1714. At Oxford he developed an interest in astronomy, encouraged by Halley who was profesor at Oxford at the time. He did not leave the church until 1721 when he took up the post of Savilian Professor of Astronomy at Oxford. Between 1725 and 1726 he worked with a wealthy amateur astronomer Samuel Molyneux at Molyneux's private Observatory in Kew where observations of the apparent displacement of Gamma Draconis led him to discover aberration. Due to the orbital motion of the Earth, and the finite speed of light, a star appears in a position slightly displaced from its actual position - this is called aberration. Between 1727 and 1748 he made observations of the Moon, from which he discovered nutation. The effect of the precession of the Earth (the 'wobble' of the Earth on its axis) caused by the gravitational pull of the Sun and the Earth is caled nutation. In 1742 he was appointed Astronomer Royal. As well as completing his work on the Moon observations, he studied Jupiter, specifically its diameter and the eclipses of its satellites. Between 1748 and 1762 he made more than 60,000 observations which were posthumously published in two volumes (one in 1798, one in 1805). Bradley also set about re-requipping the Observatory and bringing it up to date. The transit instrument which Bradley put in place remained in use until replaced by Pond in 1816. It is the Bradley meridian (the line on which the transit circle is placed) that is used in the Ordnance Survey rather than the Airy meridian from which GMT is measured. Bradley is buried in Holy Trinity Church, Minchinhampton, Gloucestershire. The artist, Benjamin Wilson (bap. 1721, d. 1788), was a portrait painter and scientist. He was appointed sergeant-painter upon the death of Hogarth in 1764 and became painter to the Board of Ordnance in 1767. Interested in chemistry and electricity, Wilson was award the Copley Medal by the Royal Society in 1760 and was employed in the development of lighning conductors for St Paul's Cathedral.
A portrait of James Bradley, 3rd Astronomer Royal, 1742-62. Benjamin Wilson.