On the non-periodic or residual motion of water moving in stationary waves

It is well known that when water moves in stationary waves, the particles do not, like pendulums, simply swing to and fro, returning after each oscillation to the points from which they started; but that each element takes up a new position after each oscillation, so that it traces out a path for itself, only returning after many oscillations to its starting point. Part of this non-periodic or residual motion, as I shall call it, in stationary waves, has been traced out mathematically by Lord Rayleigh. The object of the present paper is to show, experimentally, what it is, as completely as possible. In his classic paper “On the Circulation of Air observed in Kundt’s Tubes, and on some Allied Acoustical Problems,” Lord Rayleigh examined, among other things, the influence of the bottom of a horizontal vessel on the motion of water moving in it in stationary waves, and he came to the following conclusion: calling places of maximum horizontal motion loops, and places of maximum vertical motion nodes, “near the bottom the fluid rises from the bottom over the nodes, and falls back again over the loops, the horizontal motion near the bottom being thus directed towards the nodes and from the loops.” Quite close to the bottom, on the contrary, he found that the motion was in the opposite direction, from the nodes and towards the loops. Fig 1 shows these two sets of vortices diagrammatically.