Three motions in a man's leap; the endless aspects of a limb
Why the head outstrips the heel in jumping, shown with a hand and the moving eye
Continuing the analysis of the body, the page states that one half of a man's thickness and breadth is never equal to the other unless the joined limbs make equal and similar motions. A chapter on leaping shows that when a man jumps upward the head is three times faster than the heel and twice as fast as the hips, because three joint-angles unbend at once. A further chapter argues that no memory can retain all the aspects and changes of a limb, demonstrating this with a hand and with the eye's motion through the continuous, infinitely divisible space from a to b. Two small diagrams accompany the text: a hand set within a lettered circle (C, B, A) and a foreshortened hand marked n and m.
On this page
The three motions of leaping upward
When a man jumps upward the head is three times faster than the heel, before the tip of the foot leaves the ground, and twice as fast as the hips. This happens because three angles unbend at the same instant: the trunk joined to the front thighs, the rear thighs joined to the rear legs, and the front leg joined to the bone of the foot.
The two halves of the body never equal in motion
One half of the thickness and breadth of a man will never be equal to the other half unless the limbs joined to them make equal and similar motions. This continues the study of bodily correspondence begun on the preceding page.
No memory can hold every aspect of a limb
It is impossible for any memory to retain all the aspects or changes of any limb of any animal, a case exemplified with a hand. Because every continuous quantity is infinitely divisible, the motion of the eye that watches the hand pass through a continuous space likewise varies its aspect at every part of that motion.
Diagrams of a hand within a lettered circle
Two pen diagrams sit in the text column. In the first, a hand is inscribed in a circle whose radii are lettered C, B and A, demonstrating the eye's line of sight sweeping the circle. The second shows a foreshortened hand marked with the letters n and m, illustrating the eye moving from one point to another through continuous, divisible space.