Eddies in rivers: fast and slow whirlpools and their mixing
How delayed water rejoins the current, and how fast and slow eddies combine their force
Illustrated by whirlpool sketches in the right margin, these notes analyse river eddies (retrosi). Water delayed behind obstacles finds its only outlet where it meets the river's current, and every eddy mixes two waters, incident and reflected. Eddies turning backward belong to the faster water, those turning downstream to the slower; where the two meet they mingle and roughly double their power, the slow eddy quickening and the fast one slowing. A lettered figure (a c b d; a b fast, d c slow) adds that eddies sink against the flow in fast water and downstream in slow water.
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Where water delayed behind obstacles finds its exit
All the water that is delayed behind the obstacles in a river's current has no outlet except where it comes into contact with the current of that river.
Eddies of two waters, fast and slow, mixing their power
Eddies always mix two waters, incident and reflected: those turning backward belong to the faster water, those turning toward the river's flight to the slower. Where they meet they mingle and roughly double their power, the slow eddy becoming faster than before and the fast one acquiring slowness.
How eddies sink in fast and slow water (a c b d)
In the lettered figure, a b marks the fast water and d c the slow. The submersion of the eddies in fast water goes against the coming of the waters, while in slow water it goes toward the flight of those waters.