POND, John, English astronomer; b. Lon don, 1767; d. Blackheath, Kent, 7 Sept. 1836. He was educated at Cambridge, traveled exten sively and on his return to England in 1798 set tled at Westbury, near Bristol, where he en gaged in astronomical observations. He erected there an altazimuth instrument, two and a half feet in diameter and by a series of observations proved that the quadrant then in use at Green wich had changed its form through age, render ing the re-equipment of the Royal Observatory a necessity. He removed to London in 1807, was elected a fellow of the Royal Society and in 1811 was appointed astronomer royal. By means of the six-foot mural circle mounted by the Royal Society in 1812 Pond compiled a cata logue of the north polar distances of 84 stars, which he presented to the society in 1813. In 1821 he substituted the mercury-horizon for the plumb-line and spirit level and in 1825 origi nated the system of making observations alter nately by direct and reflected vision, for further experiments in which direction he was subse quently transferred to Queen's College, Belfast.
Though his mathematical knowledge was slight and his work wholly technical, he nevertheless performed valuable services to science and suc ceeded in introducing modern methods and in struments at the national observatory. He first used two instruments for direct and reflected observations of the same star; invented the method of observing in groups; and was the first astronomer who advocated the practice of depending upon masses of observations for all fundamental data. He was pensioned and re tired in 1835. He published a catalogue of 1,113 stars (1833), a work of great value and accuracy. His other publications include the volumes of 'Greenwich Observations,) during his astron omership; various (Papers> in the 'Transac tions' of the Royal and Royal Astronomical Societies; and a translation of the 'Systeme die Monde' of Laplace.