Impact of a square body versus a round body
Percussion acts wholly on the surface and cannot be divided in itself
At the top a parallelogram lettered S (with a and n) and a round body lettered t (with m) are shown resting on two oblique lines, comparing how each strikes a slope. Leonardo argues that although the time and the length of a heavy body's motion are divisible, the act of percussion, being made on the surface of the bodies, cannot be divided in itself. He adds that even though the square figure S strikes obliquely at a n and might seem too glancing to be effective, its blow is in fact far more powerful than that of a round body, and its rebound follows a straight line.
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The act of percussion cannot be divided in itself
Although the time in which heavy bodies move, together with the length of that motion, is divisible, it does not follow that the act of percussion, being made on the surface of those bodies, can be divided in itself.
Square body S striking obliquely at a n
Even though the figure S strikes the obliquity a n and seems, being glancing, to have no force, its percussion is much more powerful than that of a round body, and its bounce follows a straight line. The round body is lettered t and m.