Deepening a canal, and a movable weir that scours the bed
Notes on ordering the treatise 'On Benefits' and a shifting sluice that makes water scour and eddy
The left column concerns deepening a canal and how to arrange the projected treatise 'On Benefits' (de giovamenti): proofs should cite already-demonstrated propositions rather than mix practice with theory, which would confuse the order of the forty books and their illustrations; a stray optical maxim adds that no white or black is transparent. The right column describes a movable barrier (serraglio) and sluice (cateratta): opening sluice a sends water to strike the bed, leap to b, fall back and scour the eddy doubly, rising again at c, the barrier then shifted along the canal by two men per hundred. A pen sketch at the upper right shows the sluice-gate mechanism with its screw-like fitting.
On this page
Ordering the treatise on deepening a canal
The benefits of deepening a canal belong in the book 'On Benefits,' where proofs should cite already-proven propositions; showing the benefit at every proposition would force new instruments and confound the order of the forty books and their figures, mixing practice with theory.
A shifting weir that scours the canal bed
With the barrier set at S o and sluice a opened, the water strikes the bottom, leaps up to b, falls back and discharges into the eddy, scouring doubly and rising at c before falling back to repeat. The barrier can be moved along the canal by two men per hundred, opening new sluices as needed.
Sluice-gate mechanism
A pen sketch at the upper right of the right column shows the sluice-gate (cateratta) and barrier drawn in plan, with a screw-like or spiral fitting.