Impetus and percussion: a man delivering a blow
How impetus acquired along a path is consumed, and how a striker multiplies the force of his blow
The verso carries two notes on the mechanics of impetus and percussion, illustrated by a figure of a man drawn in ink. Leonardo argues that impetus cannot be spent all at once: the impetus gained along the path a-b-c-d is consumed along the line d-e, but some of its power always remains, and when the motion of d-e and the force of the mover are added, the blow at the moment of percussion is multiplied beyond what the simple impetus of d-e alone would give. The second note explains that a man who must strike a great blow with his weapon gathers all his power on the side opposite the point to be struck, because a thing in greater motion becomes more powerful against what impedes it. The figure is labelled c, b, d, a, e. Much of the surrounding surface shows faint show-through and offset from the other side of the leaf.
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Impetus consumed along a path, and multiplied at percussion
Leonardo states that impetus cannot be consumed immediately but is spent gradually along whatever line it follows. The impetus acquired along a-b-c-d is consumed along d-e, yet part of its power remains; adding the motion of d-e with the force of its mover multiplies the blow at percussion beyond the simple impetus born of the motion d-e alone.
A striker gathers his power to multiply his blow
The man who must deliver a great blow with his weapon disposes all his power on the side opposite the point to be struck. Leonardo reasons that the thing which moves more becomes more powerful over the thing that impedes its motion. The figure is annotated with the labels c, b, d, a, e.
Figure of a man in the act of striking
A man is drawn in ink at the centre of the sheet, his body twisted into the winding-up posture the text describes for delivering a blow. The pose demonstrates the mechanical argument rather than being an independent portrait.