Rosanes, Jacob:

By: Isidore Singer , Frederick T. Haneman

German mathematician; born Aug. 16, 1842, at Brody, Galicia. He received a common-school education in his native town and became a clerk in a mercantile house in Breslau, whither he had removed in 1858. Preparing himself for the university, he commenced the study of chemistry in 1860, and mathematics and physics in 1862. After receiving his Ph.D. degree from Breslau University in 1865, he continued his studies in Berlin, and returned to Breslau, where he became privat-docent in mathematics in 1870, assistant professor in 1873, and professor in 1876. In 1897 he received the title "Geheime Regierungsrat," and in 1903 was elected "rector magnificus" of his alma mater.

Among Rosanes' many essays may be mentioned: "Das einem Kegelschnitt Umschriebene und einem Andern Eingeschriebene Polygon," in Crelle's "Journal für die Reine und Angewandte Mathematik" (Berlin), lxiv.; "Dreiecke in Perspectiver Lage," in "Mathematische Annalen," ii.; "System von Kegelschnitten," ib. vi.; "Ein Princip der Zuordnung Algebräischer Formen," in Crelle's "Journal," lxxvi.; "Linearabhängige Punktsysteme," ib. lxxxviii.; "Abhängige Punktsysteme und Reciproke Verwandtschaften Zweier Ebenen," ib. xcv. He is, besides, the author of "Die Neuesten Untersuchungen in Betreff Unserer Anschauungen vom Raume," Breslau, 1871.