Draining coastal ponds with artificial eddies and siphons
The 'accidental eddy' applied to a scheme of sea, pond, river and mill-fall
A dense study of the 'accidental eddy' (retroso accidentale) and its practical use for draining coastal ponds and marshes. Leonardo shows that water swirled in a vessel bares its bottom, then applies the effect with siphons (cicognole), a horizontal 'wheel of increase' and a sealed vessel fed from a pond, all set against a lettered scheme of sea, pond, river and mill-fall. Diagrams labelled a b c, b m, m f, f g, o h n, f d, c d e and r t lay out the sea-shore, pond mouth, feeding river and siphon. He advises walling up the mechanism away from the sea and emptying the pond in June.
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Accidental eddy bares a vessel's bottom (d, c, b, a, e)
A hand turned in circles in a vessel half full of water generates an accidental eddy that bares the vessel's bottom to the air. When the hand stops, the eddy keeps turning but steadily weakens until the impetus imparted to it is spent.
Horizontal 'wheel of increase' driving a centrifuge
A horizontal water-wheel labelled 'wheel of increase' (rota d'aumento) acts on a centrifuge immersed in a vessel joined to the pond, spinning the water to raise an artificial eddy.
Sealed vessel fed only through a siphon (d'un pezzo)
The vessel is closed on every side except the bottom, where water enters only through the siphon (cicognola) brought from the pond; its crank-axle is made of one piece.
Scheme of sea, pond, river and mill-fall (a b c ... r t)
The letters set out the works: a b c the sea-shore, b m the pond's mouth, m f the pond, f g the feeding river, o h n a high canal taking all the river for the mill, f d the mill's fall, c d e the narrow canal from sea to fall, r t the siphon's mouth and t the eddy; the mouth b m is then closed.
Emptying the pond in June
When the pond stands empty in June, Leonardo closes its mouths, diverts the river that fed it, and gives it its outlet at the mill's fall.