Regulating the Naviglio: sluice-mouths and mill water
How oblique intake-mouths slow the current and starve the mills
Continuing a study of the Naviglio canal, the note argues that the intake-mouths make the water's course more oblique and therefore slower, so that in a given time a smaller sum of water is drawn into the canal and the mills receive less than before, even while receiving all of it; the mouths also silt up with refuse and clog. Leonardo then proposes to keep the canal water high at one and a half braccia as before, with the mouths at the bottom, so as to gain the water of regulation. The page is a full column of mirror-writing in brown ink with no diagram.
On this page
Oblique mouths slow the current and reduce the mills' water
The intake-mouths make the water's course more oblique and thus slower, so that in the same time a smaller sum of water is drawn into the canal and the mills receive less than before, although they receive all of it. The mouths fill with refuse and become blocked.
Holding the canal at a braccio and a half
Leonardo proposes to keep the water high in the canal at one and a half braccia as before, with the mouths at the bottom as before, so that the water of the regulation will be gained.