Using gunpowder to blast a lock and to storm walls
A military note on charging a lock with gunpowder to escape or to drive defenders from the battlements
Leonardo advises that anyone wishing to flee a locked city or other closed place should fill the lock with gunpowder and set it alight to blow it open. He adds that the same charge is useful when scaling walls, its blast serving to drive the enemy from the battlements. A red-chalk diagram of quadrilaterals, the upper one bevelled at the top, accompanies the note.
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Gunpowder charge to blow a lock and clear a wall
To escape a locked place, fill the lock with gunpowder and set fire to it. Leonardo notes the same expedient is good in scaling walls, its flash and blast driving defenders back from the battlements (merli).
Diagram of the lock
Below the note a diagram of quadrilaterals is drawn, the upper figure bevelled at the top, representing the lock or bolt to be charged. The tall vertical form suggests the housing into which the powder is packed.