Studies of spring-powered catapults
Four torsion throwing engines, with a note on releasing them together
The sheet carries four ink studies of torsion- or spring-powered catapults, each built on a timber trestle and beam frame with a curved throwing arm bent under tension. A note set beneath one of the engines directs that all the releases (lasciari) be made at one and the same moment, springing from a single cause, so that the machine's arms let go their stored force in unison. The variants explore how the arm is seated, braced and linked within its stand.
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All the releases to act at one moment
Beneath a catapult Leonardo notes that every release should be made at the same instant and proceed from a single cause. The intent is that the engine's arms let go their stored force together rather than one after another.
Four framed throwing engines
Four separate studies show catapult frames of trestle and beam construction, each carrying a curved arm and its cords. The variants examine how the throwing arm is bent, seated and braced within the timber stand.