Page:History of the Royal Astronomical Society (1923).djvu/191

 1860-70] ROYAL ASTRONOMICAL SOCIETY 163 is less strong than that to be derived from other physical phenomena. Admiral Russell Henry Manners [1800-70] was elected President in 1868. He had retired from active service in 1849. He joined the Society in 1836 and was one of the Secretaries for ten years, 1848-57 ; he then became Foreign Secretary, and held that post for ten years, till his election as President. Manners delivered the address in 1869 on presenting the Gold Medal of the Society to Stone, for his rediscussion of the Transit of Venus in 1769 and his other contributions to Astronomy. By reason of illness, Manners was unable to give the address on the award of the medal to Delaunay in 1870 February, and he died on May 9. As has been stated on an earlier page, Adams delivered the address on Delaunay's work. E. J. Stone [1831-97] was educated at King's College, London, and in 1856 went to Queens' College, Cambridge. He graduated as fifth Wrangler in 1859 an d became a Fellow of his College. In 1860 he became First Assistant at the Royal Observatory, and held the post for ten years, until he was appointed to the Cape Observatory in 1870 on the resignation of Sir Thomas Maclear. On Main's death in 1878, Stone was appointed Radcliffe Observer, and held the post until the day of his almost sudden death in 1897. He was one of the Secretaries of the Society from 1866 till 1871, Huggins being his fellow Secretary. Stone's work on the solar parallax was the chief theme of Manners's address. Airy had in 1854 and 1857 taken steps to move astronomers to a realisation of the need to revise Encke's value 8"-57, derived from the observations of the 1761 and 1769 Transits of Venus, which had been held in general acceptance from 1824 up to the beginning of this decade. Hansen had also derived from his investigations of the moon's motion a conviction that Encke's value was too low (M.N., 15, 9), and had himself deduced a value 8"-92 (M.N., 24, 8). Again Le Verrier had found in 1858 from his researches that a value of 8 "-95 was indicated. Yet again Foucault in 1854 had measured the velocity of light and found a value 185, 287 miles/sec. (298,i87km./sec.), considerably less than the value deduced by Fizeau from his avowedly preliminary experiment in 1849 (194,663 miles/sec, or 313,274 km./sec). Observations of eclipses of Jupiter's satellites were taken as indicating a value of about 192,500 miles/sec. All these lines of research called for a revision of the value of the sun's distance from the earth. Hence Airy's eagerness for a worthy attack on the problem, and the readiness with which astronomers responded to the call. Stone's reductions of observations of Mars made in 1862 at Greenwich,