Questions on Gunpowder and Bombard Firing
Powder's shape and ignition, the copper barrel, placement of touch-holes, and a bombard fired within a bombard
A page of mirror-writing without diagrams lists artillery questions about gunpowder. Leonardo observes that the faster the powder ignites the farther it drives the ball, provided the piece is of copper since other materials burst, and asks what shape powder should take to catch fire sooner or later. He then compares firing at several points along the breech versus a single point, and touch-holes set crosswise versus lengthwise, and finally imagines a bombard fired inside the barrel of another, which would give swift motion but amount to a feathered iron bolt.
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Ignition speed, powder shape and the copper barrel
The more quickly the powder catches fire, the farther it drives its ball, but only if the instrument is of copper, since of other material it breaks at once. Leonardo asks what shape the powder should have to take fire sooner or later.
Where and how to fire the charge
He weighs the difference between setting fire in several places along the length of the bombard's tail and in a single place, whether at the beginning, the middle or the third; and whether the touch-holes should be two meeting crosswise through the gun or two running lengthwise.
A bombard fired within a bombard
If within the barrel of the bombard another bombard were fired that launched its weight at the same moment it moved, this would produce swift motion; but the result, Leonardo notes, would amount to a feathered iron bar.