A Treatise on Painting/Chapter 94

by Leonardo da Vinci

Chap. XCIV.—Of the three Motions in jumping upwards.

When a man jumps upwards, the motion of the head is three times quicker than that of the heel, before the extremity of the foot quits the ground, and twice as quick as that of the hips; because three angles are opened and extended at the same time: the superior one is that formed by the body at its joint with the thigh before, the second is at the joint of the thighs and legs behind, and the third is at the instep before^[1].

1. The author here means to compare the different quickness of the motion of the head and the heel, when employed in the same action of jumping; and he states the proportion of the former to be three times that of the latter. The reason he gives for this is in substance, that as the head has but one motion to make, while in fact the lower part of the figure has three successive operations to perform at the places he mentions, three times the velocity, or, in other words, three times the degree of effort, is necessary in the head, the prime mover, to give the power of influencing the other parts; and the rule deducible from this axiom is, that where two different parts of the body concur in the same action, and one of them has to perform one motion only, while the other is to have several, the proportion of velocity or effort in the former must be regulated by the number of operations necessary in the latter.

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