Velocity of bombards: fire, powder and weight of the ball
Circle and its parts within rectangles, with proportions of the growth of fire
Continuing his study of the velocity of bombards in equal time, Leonardo states that among guns of equal powder and ball, the one igniting more fire in the same time drives its ball faster and farther. Among balls of equal weight the faster one behaves as though heavier and strikes harder, and the proportion m n bears to f g r is the proportion of the velocity of the fire's growth. Central diagrams show a circle and its parts (quarter, half, whole) framed in rectangles with a pointed rectangle, labelled a, b, c d, and m n; a marginal note advises making the charge-tail's void as high as it is long.
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More fire in equal time drives the ball farther
Among many bombards of equal powder and ball, the one in which a greater sum of fire is ignited in the same time drives its ball faster and farther. Leonardo makes the rate of ignition the measure of the gun's reach.
The faster ball seems heavier and strikes harder
Among balls of equal weight, the faster one proves heavier in effect and delivers a greater impact. Speed, not mass, governs the force of the blow here.
Circle and its parts within rectangles; proportion of fire
The framed figures carry the labels a-b, c d, a e n, f g, o r m and m n, ranging from a quarter-circle to a full wheel and a pointed rectangle. Whatever proportion m n has with f and g r, such is the velocity of the growth of their fire.
Marginal note on the charge-tail's void
Make the tail (coda) have its void as high as it is long, so that all the powder goes to the benefit of the flight. Among reinforcements of equal power, the one that better resists the breech is the one whose bombard drives its ball the less.