Friedrich Wilbelm Angnst Argelander, a German astronomer, born at Memel, March 22, 1799. He attended the university of Konigs-berg, where he at first devoted himself to political science. His attention was turned toward the study of astronomy by the lectures of Bes-sel, and in 1821 he was made his assistant in the observatory. In 1822 he was appointed an instructor in the university. In the same year he published his Untersuchungen uber die Bahn des grossen Kometen von 1811, establishing the length of the comet's period as 2,840 years. In 1823 he was made chief of a new observatory at Abo, where he passed several years, publishing in 1830 and 1832 the results of his observations in 560 different cases (Obser-vationes Astronomicœ Aboœ factœ, 3 vols., Hel-singfors), and in 1835 the determination of the positions of the stars he had observed {DLX Stellarum Fixarum Positiones Mediœ). In 1837 appeared his great work, Weber die eigene Bewegung des Sonnensystems (St. Petersburg), in which he proved the truth of Herschel's theory concerning the independent movement of the solar system.

In 1832 he had been appointed a professor at the university of Hel-singfors, and after superintending the building of an observatory, which was completed about the time of the publication of his last-mentioned work, he accepted a professorship at Bonn. Here also he took charge of the building of a new observatory, and completed it in 1845. He published in 1846 Durchmusterung des nordlichen Himmels zwischen 45° and 80° nord-licher Breite (Bonn). His other noteworthy works are: Neue Uranographie (Berlin, 1843); Atlas des nordlichen gestirnten Himmels (Bonn, 1857); and a catalogue of more than 216,000 stars, printed in the third and fourth volumes of the Astronomische Beobachtungen auf der Sternwarte zu Bonn. He was chosen a member of the French institute in 1850. Within the last ten years he has devoted himself to observations of variable stars.