Underwater Excavation for a Castle Moat
A method for laying a submerged passage, with cornel-wood pincers and long-armed digging machines
The sheet gathers notes and sketches for engineering works around a castle. Leonardo describes an excavation carried out under water 'for the amenity of a castle,' giving the dimensions of its bed and specifying that the trench be part-filled with lime, beaten level with the riverbed, and lined with solid lead. Around this are drawn a section of the moat, a pair of pincers whose handle is cased in mountain cornel wood, and several long-armed digging machines on wheeled bases. Further brief notes on the leaf were not transcribed in the bundle.
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Laying a passage under water
To make the way beneath the water, first form the bottom a to a width of 6 braccia and a height of 2. Then divide the width into three parts, that is b f c, and make f c be filled with lime, beaten down level with the bed of the river; then line it with solid lead.
Excavation under water for a castle
A trench cut beneath the water is proposed for the convenience of a castle. A section of the moat is drawn to show the profile of the submerged cut.
Cornel-wood pincers
The pincers (tanaglia) at the centre are noted as made of cornel wood, and the casing of their handle is to be made of mountain cornel. The hard, tough wood is chosen for the working tool.
Long-armed digging machines
Several machines with long booms mounted on low wheeled frames are sketched across the middle of the sheet, apparently excavators for the underwater and moat works described in the notes.