a river of Germany, entirely within the imperial territory of Alsace-Lorraine. It rises on a north foothill of the Jura, S.W. of Basel, and flows N.N.E. parallel with the Rhine, which it enters from the left, 9 m. below Strassburg. Its course lies for the most part through low meadowland; and the stream, which is 12 3 m. long, receives numerous small affluents, which pour out of the short narrow valleys of the Vosges. It is navigable from Ladhof near Colmar to its confluence with the Rhine, a distance of 59 m. It is on this river, and not on the Rhine, that the principal towns of Upper Alsace are situated, e.g. Miilhausen, Colmarl, Schlettstadt and Strassburg. The Ill feeds two important canals, the Rhine-Marne canal and the Rhine-Rhone canal, both starting from the neighbourhood of Strassburg.