OLBERS, HEINRICH WILHELM MATTHIAS (1758 1840), German astronomer, was born on Oct. 11, 1758, at Ar bergen, a village near Bremen, where his father was minister. He studied medicine at GOttingen, 1777-80, attending at the same time Kaestner's mathematical course. In 1779 he devised a new method of calculating cometary orbits. The treatise contain ing this important invention was made public by Baron von Zach under the title Ueber die leichteste and bequentste Methode die Rahn eines Cometen zu berechnen (Weimar, 5797). A table of 87 calculated orbits was appended, enlarged by Encke in the second edition (1847) to 178, and by Galle in the third (1864) to 242. In 1781, Olbers settled as a physician in Bremen, where he practised till his retirement on Jan. 1, 1823. The greater part of each night was meantime devoted to astronomy, the upper portion of his house being fitted up as an observatory. He paid special attention to comets, and that of 1815 (period 74 years) bears his name in commemoration of its detection by him. He also took a leading part in the discovery of the minor planets, rediscov ering Ceres on Jan. I, 1802, and discovering Pallas on March 28 following. His hypothesis of their origin by the disruption of a primitive large planet (Monatliche Correspondenz, vi. 88),
seemed to gain confirmation by the finding of Juno by Harding, and of Vesta by himself, in regions indicated by the hypothesis. Olbers was deputed by his fellow-citizens to assist at the bap tism of the king of Rome on June 9, 1811, and he was a member of the corps legislatif in Paris (1812-13). He died on March 2, 1840. He was twice married, and one son survived him.
See Biographische Skizzen verstorbener BremiScher Aerzte, by Dr. G. Barkhausen (Bremen, 1844) ; Allgemeine geographische Ephemeri den, iv. 283 (2799) ; Abstracts Phil. Trans. iv. 268 (2843) ; Astronom ische Nachrichten, xxii. 265 (Bessel), also appended to A. Erman's Briefwechsel zwischen Olbers and Bessel (2 vols., Leipzig, 1852) ; Allgemeine deutsche Biographic (S. Gunther). The first two volumes of Dr. C. Schilling's exhaustive work, Wilhelm Olbers, sein Leben and seine Werke, appeared at Berlin in 1894 and 'goo, a third and later volume including his personal correspondence and biography. A list of Olbers's contributions to scientific periodicals is given at p. xxxv. of the 3rd ed. of his Leichteste Methode, and his unique collection of works relating to comets now forms part of the Pulkowa library.