BERTHOLD

HALLER (1492–1536)  , Swiss reformer, was born at Aldingen in Wurttemberg, and after studying at Pforzheim, where he met Melanchthon, and at Cologne, taught in the gymnasium at Bern . He was appointed assistant preacher at the church of St Vincent in 1515 and people's priest in 1520 . Even before his acquaintance with Zwingli in 1521 he had begun to preach the Reformation, his sympathetic character and his In 1696 he was, although a zealous Tory, appointed deputy comptroller of the mint at Chester, and (August 19, 1698) he received a commission as captain of the " Paramour Pink " for the purpose of making extensive observations on the conditions of terrestrial magnetism . This task he accomplished in a voyage which lasted two years, and extended to the 52nd degree of S. latitude . The results were published in a General Chart of the Variation of the Compass in 1701; and immediately afterwards he executed by royal command a careful survey of the tides and coasts of the British Channel, an elaborate map of which he produced in 1702 . On his return from a journey to Dalmatia, for the purpose of selecting and fortifying the port of Trieste, he was nominated, November 1703, Savilian professor of geometry at Oxford, and received an honorary degree of doctor of laws in 1710 . Between 1713 and 1721 he acted as secretary to the Royal Society, and early in 1720 he succeeded Flamsteed as astronomer-royal . Although in his sixty-fourth year, he undertook to observe the moon through an entire revolution of her nodes (eighteen years), and actually carried out his purpose . He died on the 14th of January 1742 . His tomb is in the old graveyard of St Margaret'schurch,Lee, Kent . Halley's most notable scientific achievements were—his detection of the " long inequality " of Jupiter and Saturn, and of the acceleration of the moon's mean motion (1693), his discovery of the proper motions of the fixed stars (1718), his theory of variation (1683), including the hypothesis of four magnetic poles, revived by C . Hansteen in 1819, and his suggestion of the magnetic origin of the aurora borealis; his calculation of the orbit of the 168e comet (the first ever attempted), coupled with a prediction of its return, strikingly verified in 1759; and his indication (first in 1679, and again in 1716, Phil .

Trans., No . 348) of a method extensively used in the 18th and 19th centuries for determining the

solar parallax by means of the transits of Venus . His principal works are Catalogus stellarum australium (London, 1670), the substance of which was embodied in vol. iii. of Flamsteed's Ilistoria coelestis (1725); Synopsis astronomiae cometicae (Oxford, 17o5); Astronomical Tables (London, 1752) ; also eighty-one miscellaneous papers of considerable interest, scattered through the Philosophical Transactions . To these should be added his version from the Arabic (which language he acquired for the purpose) of the treatise of Apollonius De sectione rationis, with a restoration of his two lost books De sectione spatii, both published at Oxford in 1706; also his fine edition of the Conics of Apollonius, with the treatise by Serenus De sectione cylindri et anti (Oxford, 1710, folio) . His edition of the Spherics of Menelaus was published by his friend Dr Costard in 1758 . See also Biographia Britannica, vol. iv . (1757) Gent . Mag. xvii . 455, 503; A . Wood, Athenae Oxon . (Bliss), iv . 536; J .

Aubrey, Lives, it . 365; F . Baily, Account of Flamsteed; Sir D . Brewster, Life of Newton; R . Grant, History of Astronomy, p . 477 and passim; A . J . Rudolph, Bulletin of Bibliography, No.14 (Boston, 1904) ; E . F . McPike, ' Bibliography of Halley's Comet," Smithsonian Misc . Collections, vol. xlviii. pt. i . (1905); Notes and Queries, 9th series, vols. x. xi. sit., Loth series, vol. ii .

(E . F . NlcPike) . A collection of

manuscripts regarding Halley is preserved among the Rigaud papers in the Bodleian library, Oxford; and many of his unpublished letters exist at the Record Office and in the library of the Royal Society . (A . M .