The Dents Left by a Ball Striking at Angles
How condensed air deflects a ball whose path is off-centre
Two quarter-circle diagrams at the head of the page, lettered a m b - n - c, show spheres striking a horizontal and an oblique plane. The text argues that the marks a heavy spherical body leaves do not stand in the same proportion to one another as the obliquity of the sites where they strike. Leonardo blames the discrepancy on the air condensed ahead of the ball: because that air cannot move as fast as the ball driving it, it packs denser the harder the ball is thrown, so that a ball whose line of travel is not central is deflected. The passage breaks off mid-sentence.
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Impact marks and the condensation of driven air
The dents left by a spherical body do not keep the same proportion to one another as the obliquity of the surfaces struck. Leonardo attributes this to air condensed ahead of the ball, which packs ever denser the harder the ball is driven and deflects a ball whose path is not central.
Spheres striking horizontal and oblique planes (a m b - n - c)
Two quarter-circle constructions lettered a m b - n - c set a ball against a horizontal plane and against an oblique one, providing the geometric frame for comparing the impact marks made at differing angles.