Vortices where water strikes a submerged block
Reflection of currents, converging flows in a narrows, and scouring around a stone in a river
Leonardo studies how a mass of water striking a submerged obstacle (the block f, upper right) coils into vortices: the lower water hits the bottom and reflects to the surface, meets the upper water, and the two unite and turn together. A second note treats water falling within water in a narrows, where the flow near the middle of the fall is more oblique than at the edges. A lower diagram of a stone block (a n c b) in a river shows the bed scoured more on the side facing the greater current, where a larger wave and eddy form, while the bank breaks at n.
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Vortices from water striking a submerged object (f)
Such coilings of currents arise from the impetus of water beneath other water. The lower part of the struck mass strikes the bottom first and reflects immediately to the surface; the upper half, meeting it, is thrust back and reflects along the same lines and whirls. Where the lower and upper waters meet, they unite and turn together.
Water falling within water in a narrows
Of the water that falls amid other water, the part nearest the middle of the fall is more oblique, and that nearest the edges is more straight. The middle drawing shows converging currents clashing in a constriction.
Stone block scouring the river bed (a n c b)
At a b the bottom is scoured more than on the opposite side, because toward the greater current of the river a larger wave and eddy form at a b than on the other side, as the object f shows above. At n the bank is broken.