JOHN

See also:

• POND
• JOHN POND (c. 1767-1836)

POND (c. 1767-1836)  , English astronomer-royal, was born about 1767 in London, where his father made a fortune in trade . He entered Trinity College, Cambridge, at the age of sixteen, but took no degree, his course being interrupted by severe pulmonary attacks which compelled a long residence abroad . In 1800 he settled at Westbury near Bristol, and began to determine star-places with a fine altitude and azimuth circle of 22 ft. diameter by E . Troughton: His demonstration in 18o6 (Phil . Trans. xcvi . 420) of a change of form in the Greenwich mural quadrant led to the introduction of astronomical circles at the Royal Observatory, and to his own appointment as its head . He was elected a fellow of the Royal Society on the 26th of February 18o7; he married and went' to live in London in the same year, and in 1811 succeeded Maskelyne as astronomer-royal . During an administration of nearly twenty-five years Pond effected a reform of practical astronomy in England comparable to that effected by Bessel in Germany . In 1821 he began to employ the method of observation by' reflection; and in 1825 he devised means (see Mem . Roy . Astron . Soc. ii .

499) of Combining two mural circles in the determination of the

place of a single object, the one serving for direct and the other for reflected vision . Under his auspices the instrumental equipment at Greenwich was completely changed, and the number of assistants increased from one to six . The superior accuracy of his determinations was attested by S . C . Chandler's discussion of them in 1894, in the course of his researches into the variation of latitude (Astron . Journ . Nos . 313, 315)/ He persistently controverted (1810-1824) the reality of J . Brinkley's imaginary star-parallaxes (Phil . Trans. cviii . 477, cxiii . 53) .

Delicacy of

health compelled his retirement in the autumn of 1835 . He died at Blackheath on the '7th of September 1836, and was buried beside Halley in the churchyard of Lee . The Copley medal was conferred upon him in 1823, and the L'alande prize in 1817 by the Paris Academy, of which he was a corresponding member . He published eight folio volumes of Greenwich Observations, translated Laplace's Systkme du monde (in 2 vols . 8vo., 1809), and contributed thirty-one papers to scientific collections . His catalogue of 1112 stars (1833) was of great2 (After Wossidlo . From Strasburger's Lehrbuch der Botanik.) Potamogeton natans . 1, Apex of flowering shoot . 3, Flower viewed from the side . 2, Flower viewed from above . 4, Diagram of flower . axillary or terminal spikes; they have four stamens, which bear at the back four small herbaceous petal-like structures, and four free carpels, which ripen to form four small green fleshy fruits, each containing one seed within a hard inner coat; the seed contains a large hooked embryo: An allied genus Zannichellia (named after Zanichelli, a Venetian botanist), ' occurring in fresh and brackish ditches and pools in Britain, and also widely distributed in temperate and tropical regions, is known as horned pondweed, horn the curved fruit .