German. A term used In topography to designate a line representing the deepest part of a continuous depression in the surface, such as a watercourse; hence the middle of the deepest part of the channel of a river or other stream. See Iowa v. Illinois, 147 U. S. 1, 13 Sup. Ct 239, 37 L. Ed 55; Keokuk & H. Bridge Co. v. People, 145 111. 596, 34 N. E. 482.