“ The principal towns on its banks are Würzburg and Frankfort. The Main, in spite of its length, is not very important from a commercial point of view, owing to frequently occurring shoals and the tortuousness of its course. It has, however, been canalized between Mainz and Frankfort, so as to admit vessels of 1000 tons, and its waters communicate with those of the Danube by means of the Ludwigs-Kanal. ”