DOUBLE SILING, detail

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. A single mallet knock pushes down the rocker, which unhooks the two cog-wheels from the worms: the ropes instantaneously untwist, hurling the stones in the air.