Falarica engines and a caisson for emptying a harbour
With a note on hearing distant ships through a blowpipe and a recipe for crocus of iron
The upper half of the sheet shows two views of a falarica, an ancient spear-throwing engine, drawn in ink over faint mirror-script. On the right Leonardo notes that a blowpipe held with one end in the water and the other at the ear lets one hear distant ships, and he gives a recipe distilling vitriol and saltpetre with iron filings to make crocus of iron. The lower left shows a large square caisson, forty braccia on a side, for baring the bottom of a harbour so it can be worked. Further untranscribed mirror-script fills the right margin.
On this page
Two views of the falarica engine
Two drawings at the top of the sheet are each labelled falarica, an ancient throwing engine. Leonardo repeats the name over a second, analogous figure. The framed timber structures carry curved arms suggesting the throwing mechanism.
Caisson for emptying a harbour (a b - c d)
A large open coffer, forty braccia on each side, is sunk to bare the harbour bottom. Once the bottom within is emptied, one face is left standing and the other three are shifted beyond it, and the process is repeated. The points a b and c d mark the structure.
Blowpipe as a listening device
Leonardo describes setting one end of a cerbottana (blowpipe) in the water and the other at the ear to hear ships far off, or resting it on the ground to hear people passing at a distance. The same passage adds a distillation of vitriol and saltpetre with iron filings to yield crocus of iron.