LAHN  , a

river of Germany, a right-bank tributary of the Rhine . Its source is on the Jagdberg, a summit of the Rothaar Mountains, in the cellar of a house (Lahnhof), at an elevation of 1975 ft . It flows at first eastward and then southward to Giessen, then turns south-westward and with a winding course reaches the Rhine between the towns of Oberlahnstein and Niederlahnstein . Its valley, the lower part of which divides the Taunus hills from the Westerwald, is often very narrow and picturesque; among the towns and sites of interest on its banks are Marburg and Giessen with their universities, Wetzlar with its cathedral, Runkel with its castle, Limburg with its cathedral, the castles of Schaumburg, Balduinstein, Laurenburg, Langenau, Burgstein and Nassau, and the well-known health resort of Ems . The Lahn is about 135 M. long; it is navigable from its mouth to Giessen, and is partly canalized . A railway follows the valley practically throughout . In 1796 there were here several en-counters between the French under General Jourdan and the troops of the archduke Johan, which resulted in the retreat of the French across the Rhine .