Seven cannon and falcon barrels with their dimensions
A French cannon, four large cannons and two falconets, each measured in braccia and inches
The sheet presents seven artillery barrels drawn upright in elevation, each labelled and paired with a column of measurements giving length, bore, wall thickness and the placement of the trunnion (polo). They range from an ornamented French cannon, through a small old cannon and several large new cannons (including one with a twelve-sided body), to two falconets, old and new. For the French piece Leonardo states a founder's rule: divide the barrel's mouth diameter into eleven parts, keep seven for the bore, and let the remainder form the thickness of the metal. All lengths are given in braccia and inches (once, twelfths of a braccio).
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French cannon: bore, tail and the eleven-part metal rule
The ornamented barrel at the far left is the French cannon, marked a b. Its bore is 3 1/2 inches throughout the whole barrel except at the tail, where it narrows to 3 inches, and the housing of the tail is 1 1/4 braccia. Leonardo adds a proportioning rule: divide the diameter of the barrel at the top into eleven parts, leave seven for the bore, and the rest becomes the thickness of the metal.
Small old cannon, four braccia long
The second piece is a small old cannon. Its thick middle body is 1 braccio 5 inches long and 7 1/2 inches thick outside, tapering half an inch toward the muzzle; the mouth is 3 1/2 inches thick. The trunnion begins beyond the middle of the barrel, whose whole length is 4 braccia.
Twelve-sided cannon a, built without a tail
A large new cannon of twelve sides, marked a, measures 5 braccia from the rear cornice to the muzzle. It is built without a tail, only a little work of 1 1/2 inches beyond the small square a. The clear breech shaft is 7 3/4 inches thick and the trunnion sits below the middle of the barrel's length.
New and old falcons with eight-faceted shafts
The sixth piece, a new falcon marked a, is 4 braccia 3 inches long from the square a to the muzzle; all falconets carry their tail in one piece with the rest. Its shaft is faceted into eight faces for 2 1/2 braccia and round beyond. The seventh, an old falcon, is shorter and likewise eight-angled at the mouth.
Proportioning bore to metal by dividing the diameter
The measurements throughout are handled as ratios: the mouth diameter is split into eleven parts, seven for the void and four for the metal wall. Each barrel's breech, middle and muzzle are given as fractions of a braccio, and tapers are noted in fractions of an inch.