The walls of a rectangular horizontal channel, the bottom of which was smooth, were lined with corrugated iron arranged to give a shore line of alternate bays and capes. When water passed through the channel with a well-marked critical velocity, a continuous train of self-induced waves was formed on the surface, and moved steadily upstream into the contraction which led from the supply reservoir. With a narrow stream the waves possessed horizontal transverse crests and troughs, but above a certain width the waves were antisymmetrical. With different combinations of channels and corrugations, the mechanism was examined by which energy was taken from the stream to maintain the waves. Linings of rectangular capes and bays produced higher-order waves, and the effect was largely independent of the number of bays.