V. On the origin of windings of rivers in alluvial plains, with remarks on the flow of water round bends in pipes

Abstract

In respect to the origin of the windings of rivers flowing through alluvial plains, people have usually taken the rough notion that when there is a bend in any way commenced, the water just rushes out against the outer bank of the river at the bend, and so washes that bank away, and allows deposition to occur on the inner bank, and thus makes the sinu­osity increase. But in this they overlook the hydraulic principle, not generally known, that a stream flowing along a straight channel and thence into a curve must flow with a diminished velocity along the outer bank, and an increased velocity along the inner bank, if we regard the low as that of a perfect fluid. In view of this principle, the question arose to me some years ago:— Why does not the inner bank wear away more than the outer one ? We know by general experience and obser­vation that in fact the outer one does wear away, and that deposits are often made along the inner one. How does this arise ? The explanation occurred to me in the year 1872, mainly as follows:—