Falling water: sheets, jets and the mill-wheel vortex
Six short notes and diagrams on water dropping onto flat water, meeting jets, and hollowing beneath a board
A page densely illustrated with hydraulic sketches, including a forked jet, a plank or sluice structure, arcing streams and a strong swirling vortex at the lower right. The short captioned notes examine how water falling onto shallow flat water uncovers the bed, how two falls meet, and how a sheet of water rebounds. Leonardo observes that water always hollows out beneath a board it passes under, proposes measuring how deeply an oblique fall digs beneath the surface, and notes that water turns in front of an incident jet like a mill wheel.
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Falling water uncovers the shallow bed
Water falling along different lines onto a flat place, where the water is shallow, uncovers the bed beneath it. Leonardo adds that the concatenation (the linked continuity) of the water is little or not at all separated by the percussion of the fall.
A sheet of water rebounding at c
In a labelled figure (a n, b, m), the sheet-like water a b rebounds at c. Leonardo weighs whether it is drawn up by the water m or goes there of itself toward the water n m.
Water hollows out beneath a board
For water passing under planking, marked a b, Leonardo notes that it always empties out and hollows beneath the board a b.
Water turning like a mill wheel
After a fall, the water boils up: it turns in front of the incident water like a mill wheel. This describes the swirling rotary motion drawn as a vortex at the lower right of the sheet.