Reinforced Withy Bundles, and Draining the Piombino Marsh
A torsion test of corded fascines, a marsh-draining scheme, and a small balance schema
The sheet studies the strength of bundles of withies (thin flexible rods) under torsion, drawn in three states: an unbound bundle, one corded in a single direction, and one bound in two directions. Leonardo proposes an experiment: bind the bundle e f tightly with the cord e–n–f, then twist its ends in contrary directions with levers a (along line a b) and c (along line c d); the corded bundle cannot be turned unless it thins in itself or the cord stretches or breaks, while the doubly-bound bundle can never be twisted at all. At the foot of the page a small topographic sketch is labelled "Way to drain the marsh of Piombino," and above the centre a short balance schema records the numbers 3, 11, 2 and 7 1/3.
On this page
Torsion test of a corded bundle of withies
The bundle e f, tightly bound by the cord e–n–f, is twisted at its ends in contrary directions by levers a (turned along a b) and c (turned along c d). Experience shows it cannot be turned unless it thins within itself or the cord stretches or breaks, so a bound bundle is far stronger than a single piece.
A bundle bound in two directions resists all twisting
A bundle armed (bound) in two directions will never be twisted in any way, unlike the thin withies that farmers twist to make them pliable and fit for binding faggots of tree branches.
Draining the marsh of Piombino
A small topographic sketch at the foot of the sheet is captioned as a way to drain (dry out) the marsh of Piombino; within the drawing a note begins "property which..." and breaks off.
Balance schema with numbers
Above the centre of the sheet a small balance diagram carries a short column of figures: 3 11 / 3 11 2 / 7 1/3 2.