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Piazzi, Giuseppe

PIAZZI, GIUSEPPE (1746-1826), PIAZZI, JOSEPH, was born at Ponte in the Valteline (Switzerland), July 16, 1746. His education appears to have commenced at Milan, where he assumed the habit of the Theatins, and became an inmate of the convent of St. Anthony. Here and at Turin he studied the classics and mathematics under Tiraboschi and Beccaria, and at Rome under Lesueur and Jacquier, the editors of the Jesuits' edition of the ' Principia.' He began to teach philosophy at Genoa; but having expressed himself too openly on certain theological points, he was threatened with the persecution of the Dominicans, from which he escaped by accepting the professorship of mathematics in the new university of Malta, conferred upon him by the grandmaster Pinto. Upon his return to Italy, he became professor of philosophy and mathematics in the College of the Nobles at Ravenna; but here again his religious opinions made him many enemies. Soon after the publication of two philosophical theses, which were deemed ' too hold for so yoiing a divine,' he found it expedient to retire, first to Cremona, and thence to Rome, where he was for some time reader 6f dogmatic theology at S. Andre della Valle. In 1780, at the recommendation of Jacquier, ho was appointed professor of the higher mathematics in the Academy of Palermo, where, with the co-operation of the viceroy, ho founded an astronomical observatory. In 1787 he visited Paris, where he made the acquaintance of Lalande, Jeaurat, Pingrf, Dclambre, and Bailly; also of John Cassini, Mechain, and Lcgendre, who were at that time occupied in determining the difference of longitude between the observatories of Paris and Greenwich. He next visited England, where he became intimate with Maskelync, Herschel, Vince, and more particularly with Ramsden, to whom he confided the construction of the instruments for his new observatory. Much of his time during his slay in England was passed at the observatory of Greenwich. Here, with Dr. Maskelync, he observed the solar eclipse of June 3, 1 788; and the year following he communicated a paper to the Royal Society (Phil. Trans., vol. 79, p. 55), containing the observations of that eclipse by twelve other astronomers, and the consequences thence deduced by himself relative to the longitudes of the several observatories. At that time the longitude of the Dublin observatory was taken at 24m 58s; Piazzi gives 25TM 13'4*, and expresses his confidence that this is within two seconds of the truth: the longitude now given in the ' Nautical Almanac' is 25m 22s. This paper is understood to be his earliest production as an astronomer. Having after much importunity obtained the completion of his instruments, he returned with them to Sicily in the latter part of the year 1789, and very soon after became one of the most active and accurate of modern observers. The observatory of Palermo was nt that time the most southern in Europe, that at Malta having been recently destroyed by fire. In the course of the first ten years he determined the positions of nO less than 6748 stars. His first catalogue was published in 1803, under the title of 'Stellarum Inerrantium Positiones,' which was deservedly honoured by the Academy of Sciences of Paris, and acquired for its author the esteem and admiration of astronomers. It was while thus occupied 1hat he discovered, January 1, 1801, the first of the four planets now known to be situated between the orbits of Mars and Jupiter, and to which he gave the name of Ceres Ferdinandea, out of comliment to his patron the king of Naples. [ceres.] Ferinand would have commemorated the event by circulating among the astronomers of Europe a gold medal bearing tho effigy of Piazzi; but the latter suggested that the money would be more usefully applied in the purchase of an equatorial, of which the observatory was in need.

In 1817 he was called to Naples to put into activity the new observatory erected by Murat on the heights of Capo di Monte. He was succeeded in the observatory of Palermo by M. Cacciatore, to whom he had previously confided the difficult task of re-examining Maskelyne's thirty-six principal stars. The observations of Cacciatore, which were extended to 120 stars, form the basis of Piazzi's second Catalogue of 7646 stars, published in 1814. Speaking of this catalogue, the council of the London Astronomical Society remark, in their seventh annual Report, that 'it exceeds everything of the kind which preceded it, and shows more powerfully than words can express what may he effected by the talents and assiduity of one individual.' Piazzi was a member of the principal scientific societies of Italy, France, and Germany. Of the Royal Society of London he was elected a fellow in 1804, at the same time with Baron Zach and Professor Gauss. He died at Naples, July 22, 1826. His library and instruments he bequeathed to the observatory of Palermo, and a liberal annuity in perpetuity, to be appropriated in succession to the education and maintenance of young men who evince a marked partiality for astronomical science. The preceding notice is chiefly drawn from an article in the 'Bulletin des Sciences' for 1826, drawn up by De Angelis under the eye of the Baron Zach. A more detailed account of Piazzi's life and labours has long been expected from the pen of his friend Colonel Visconti, the present director of the geographical engineers at Naples. The published works of Piazzi mentioned in different numbers of the ' Bulletin des Sciences' are collected and appended to a translation of the above article in Brewster's 'Journal' for 1827 (vol. vi., p. 193). They are as under:—

1, 'Discourse on Astronomy,' Paler., 1790.

2, 4 Description of the Observatory of Palermo,' in 9 books, of which four were published in 1792 and five in 1794.

3, 'On the Discovery of the Planet Ceres,' Palermo, 1802.

4, 'Observations on the Obliquity of ike Ecliptic,' 1804. {Mem. Soc. Haliana, torn, xi.)

5, 'On the Precession of the Equinoxes,' 1804. (Ephem. de Milan.)

6, 'On the Parallax of some of the Fixed Stars.' (Mem. Soc. Italiana, xii.)

7, 1 On the Measure of the Tropical Year.' (Id., tome xiii.')

8, 'On the Proper Motion of the Fixed Stars.' (Mem. de Vlnst. Nat. Ital., tome i.)

9, 'The Metrical System for Sicily,' 1812.

10, 'Lessons in Astronomy,' 1817.

11, 'On the Observed and Calculated Solstices." (Mem. de I Inst, de Milan, tome ii.)

12, ' On the Italian and European Clock.' (Giom. de Scienze par la Sicilia, Aug., 1824.)

13, 'On the Progress of Astronomy." (Giorn. de Sue. Lett, et Arti far la Sicilia, April, 1824.

) 14, 'Desciiption of the Meridian of the Cathedral of Palermo, established by Piazzi in 1798,' by M. Cacciatore. (Id., August, 1824.)

See B. E. Maineri, L'Astronomo Giuseppe Piazzi (Milan, 1871); R. Wolf, Biographien, Bd. iv. p. 275; Monatliche Correspondenz (1810; portrait), xxi. 46; Astr. Jahrbuch, liv. 218; Bulletin des sciences (1826), vi. 339; Edin. Journal of Science (1827), vi. 193; Memoirs Roy. Astr. Soc. iii. 119; R. Grant, Hist. Phys. Astronomy, pp. 238, 510, 549.

Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)

Note - this article incorporates content from The Penny Cyclopaedia of the Society for the Diffusion of Useful Knowledge (1840)

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