How a Cross-Current Breaks a Riverbank and Sorts the Debris
A stream falling across the current cuts the embankment and scatters large stones, small stones and sand by size
Leonardo analyses how a stream falling crosswise to a river's current strikes and breaks the embankment. He follows the action from the break shown at a b to the ground torn open at f, and observes that the water sorts the debris it lifts, dropping the large stones at S, the smaller ones at h, and the coarse earth or sand at g. The verso carries his mirror-script beside a pen sketch of the scoured, broken bank.
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A falling cross-current breaks the embankment at a b
The falling motions that descend crosswise to the river are what break the bank, as is shown at a b. The same motion then breaks open the ground at f.
The water sorts the debris by size: stones at S, sand at g
Having lifted the material, the water unloads its large stones at S, the smaller ones at h, and the coarse earth or sand at g. Leonardo reads the deposit as a record of the current's sorting power.
Pen sketch of the broken, scoured bank
A pen drawing accompanies the note, showing the hatched scarp of the embankment broken away and the loosened material scattered below it.