Folio 90v of Codex Madrid I contains a design with three rods bound to a large wheel - the clues found by the Leonardo3 research center imply that the drawings refer to the Mechanical Lion, which Leonardo built to walk before the King of France and offer him lilies as a gift. The fundamental drawing is found in the upper part of folio 91r. The same corded mechanism of folio 90v appears twice, with a wheel in the middle. The design represents the movement of a leg whose three segments are supposed to be a thigh, a tibia and a paw. The drawing on folio 91r confirms the theory of a mechanism that imitates the movement of a quadruped’s legs. There is a wheel in the small drawing on the left-hand side of folio 91r that could very well be the central wheel that pulls the ropes. The way they are mounted would allow the ropes to remain separate for each rotation. As for the mechanisms that make the lion move and stop autonomously and open both its mouth and a little door on its chest from which previously-loaded flowers are made to fall, we can only make speculations. The energy for the autonomous movement could be supplied either by an internal spring connected to the main wheels with a tight rope or by a simple gear. The ideal point at which to place the spring is in the middle of the pelvis so as to contain both the weight and resulting center of gravity between the points of support: the tail and the central wheels. An intermediate gear placed right above the supporting wheels in line with the spring could be used to connect the spring to the wheels. The lion’s walk is artificial: while its legs move, the wheel that rotates at its base is what actually makes it move forward, and the only reason the lion can stand is because of the stability provided by its tail. To make the lion stop after advancing a certain distance, we could either use a transmission connected to a cam that blocks the forward-movement system with a stop or we could simply allow the spring to run out of energy. When the lion stops, the forwardmovement system could release a hook, thereby causing the chest to open automatically. The lilies could thus slide down the open throat and fall the ground, thereby completing the action.
Codex Madrid I, folios 90v, 91r