Parapets, Merlons and the Bomb-proof Casemate
Cordons and machicolations, tower-top pyramids or huts, dummy ravelins, and a thick-walled casemate
A text page (folio 96v) detailing the upper works of the towers and a bomb-proof casemate. Leonardo specifies a parapet three feet high and merlons a foot and a half thick (six feet where artillery is feared), a half-round cordon and a throat beneath the corbels to hinder escalade, and tower-tops finished as a round pyramid, half-sphere or hut, or hollowed with steps in place of merlons. He allows dummy triangular ravelins at the turret feet, provided the bombards cannot reach them. The last passage describes a casemate of walls five to six feet thick with a void of twelve to fourteen feet and smoke-vents over the embrasures, reached from the keep by a difficult subterranean way and set eight feet from the ditch wall against mining. A small stepped profile is sketched in the lower left margin.
On this page
Parapet, merlons and the anti-escalade cordon
The parapet is 3 feet high and a foot and a half thick, with merlons of the same thickness, or 6 feet where artillery is feared. Beneath the corbels runs a half-round cordon projecting 3 feet, with a smooth flat face below against escalades, and above it a throat projecting a foot and a half from which the wall runs straight before the corbels resume.
Pyramid, half-sphere or hut atop the tower
The tower's summit may be finished as a round pyramid with defences at its feet, as a half-sphere, or as a hut with its entrance open toward the principal tower. Alternatively the top may be hollowed with three or four steps diminishing toward the centre, serving in place of merlons once the others are thrown down.
Dummy ravelins at the foot of the turrets
For added defence of the turrets and walls one may build dummy ravelins, triangular or as one pleases, at their feet. But they must not stand where the bombards can find them, since that would weaken the towers, even though such works help resist the enemy more easily.
The thick-walled casemate with smoke-vents
Where heavy siege engines cannot reach, a hut-like casemate is made of walls five to six feet thick, its void twelve to fourteen feet across and eight high, with smoke-vents over the embrasures. It is built against the keep wall and reached from the keep by a most difficult subterranean way, and stands eight feet from the ditch wall so it cannot be harmed by mining.
Marginal sketch of a stepped tower profile
A small drawing in the lower left margin shows a stepped, terraced profile, illustrating one of the tower-top or scarp arrangements the text describes. It is a faint pen sketch beside the prose.