A balance-and-catapult rig for testing throwing power
Apparatus of equal arms m and n, with a suspended platform and cylinders
The page carries pen sketches of an experimental apparatus and text describing how to use it. At left a balance arm resembling a small catapult (labelled n and m) holds a ball; at right a frame suspends weighted cylinders over a hanging platform, and the Bibliotheque de l'Institut stamp appears at centre-right. Leonardo directs that the wood n match the size of the ball and the whole balance be sized to it, that the arms m and n be of equal length and weight, and that the striking weight and the mobile weight always stay equidistant from the centre of the balance, so as to test the ultimate power of things that throw weights.
On this page
Balance apparatus with arms m and n (catapult c-n-m)
The instrument is a balance whose arms m and n must be of equal length and weight, with the wood n made the size of the ball and the whole balance scaled to it. The centre of the striking weight and the centre of the mobile weight are to remain equidistant from the centre of the balance. Leonardo directs only two trials, using a double weight (double by weight, not by figure).
Testing the ultimate power that moves and throws weights
The rig is built to test the ultimate power of things that move and throw weights, giving them more or less weight so one can see which weight travels furthest from its mover. Every test-body is to be of round figure and the same material, isolating weight as the only variable. The mobile that goes farthest marks the weight proportionate to that power.