"When you will have turned the wheels that twist the ropes, put in the staves for the slings."
"All these instruments are in one same work. Make the arms of the crossbow open 20 braccia and have the staves for the slings be 10 braccia, and the stone 50 pounds."
This double catapult is one of the many drawings by Leonardo which describe and interpret the large medieval war machines. Thanks to the movement of cog-wheels and worms, the ropes are twisted to hold and bring closer the two crossbows. Then the two poles are engaged and the machine is charged with stones. E single knock pushes down the rocker, which unhooks the two cog-wheels from the worms: the ropes instantaneously untwist and throw the stones.
The model is based on the drawing:
- Codex Atlanticus f. 152 r. (1485)
Milano, Biblioteca Ambrosiana