PIAZZI, Giuseppe, joo-sep'pe pe-at'se, Ital ian astronomer: b. Ponte, Valtellina, Italy, 16 July 1746; d. Naples, Italy, 22 July 1826. He was educated in Milan, Turin and Rome, and appointed professor of mathematics at the Uni versity of Malta in 1770, where he remained until its abolition in 1780. In the same year he accepted the chair of mathematics at Palermo, where, through his efforts, an observatory was established in 1789. Previous to its opening he made a journey to England where he established friendly relations with the English astronomers Maskelyne, Herschel, Vince and Ramsden. At his new observatory he made important investi gations, the results of which were published in 1792, and in 1801 he discovered the first of the planetoids known to science, which he named Ceres. Though it was visible for but a short time his observations were sufficient to com pute its orbit so that it was found in the fol lowing year. In 1803 he completed his first catalogue of the fixed stars, which contained 6,784 stars, and received a prize from the In stitute of France at Paris, to which it was ded icated. His second catalogue containing 7,646
was completed in 1814 and also received recogni tion from the Institute at Paris. This catalogue has been of great and lasting value and Piazzi's observations are now being used in a new com putation by modern methods. He also made valuable discoveries concerning comets, and in 1817 was appointed chief director of the govern ment observatory at Naples. His most import ant work after his catalogue was ele mentarii di Astronomia> (2 vols., Palermo 1817). The Kaiserlich-Mnigliche Sternwarte, Vienna, has published in its 'Annalen' (2 series, Vols. IV—XII, Vienna 1841-51) a collection of his observations under the title 'Piazzis Beo bachtungen, 1792-1813.' Consult Edinburgh Journal o Science (Vol. VI, p. 193, Edin burgh 1827), containing a list of his works; Grant, R., 'History of Physical Astronomy' (London 1852) ; Mameri, B. E., 'L'Astronomo G. Piazzi) (Milan 1871).