James Bradley, Astronomer Royal (circa 1692-1762), 17th century (mezzotint)

Creator: Thomas Hudson (artist); Johan Faber (engraver & publisher) Jacobus Bradley, S.T.P. Regalis Societatis Socius Astronomus Regius et apud Oxonienses Astronomiae Professor Savilianus'. In 1742 Bradley was appointed Astronomer Royal. Bradley had studied theology at Balliol College, Oxford between 1711-1714. He later worked with Molyneux at Molyneux's private Observatory in Kew, where observations of the apparent displacement of Gamma Draconis led him to discover aberration. Between 1727 and 1748 he made observations of the Moon, from which he discovered nutation. He also studied Jupiter, specifically its diameter and the eclipses of its satellites. Between 1748 and 1762 he made more than 60,000 observations. As Astronomer Royal, Bradley in 1750 established a new Greenwich meridian for altitude observations, slightly east of and replacing those of Flamsteed and Halley. This became the longitudinal baseline of the original Ordnance Survey of Britain later in the century. After Airy's meridian some 19 feet further east was establishd in 1851, and in 1884 became Longitude 0 degrees for the world, the discrepancy was noticed but judged to small to warrant cartographic adjustments for land use. Bradley's meridian is therefore still the basis of British land maps. This portrait by Hudson (of which the original oil of 1742-1747 belongs to the Royal Society) was re-engraved several times. A steelplate version appears, for example with Bradley's biography, in Charles Knight's seven volume 'Gallery of Portraits' (1836).