A wedge driven under a beam, and a perspective diagram
A counterweight problem in mechanics beside a study of a figure's height on the picture plane
The sheet carries two distinct investigations in red chalk. At the top and bottom Leonardo sets a mechanics problem: a wedge n is driven and held beneath a beam, and he asks where it will come to rest given the counterweight S that pulls on it. In the middle, under the heading "Prospettiva," a diagram lettered f, a, t, e demonstrates how the distance from the eye governs the apparent height of a man measured on the picture plane.
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Wedge n held under a beam by counterweight S
A wedge (conio) marked n is pulled and forced under a beam, with a hanging counterweight S drawn in a box at left. Leonardo poses the question of exactly where along the beam the wedge n will come to rest through the pull of the counterweight S. The labels 8, n and S key the drawing to the text.
Height of a man measured on the picture plane
Under the heading "Perspective," a diagram lettered f, a, t, e treats diminution with distance. Leonardo lets f be the height and distance from the eye, a the plane on which a man's height is projected, and t a man, arguing that the distance on the plane corresponds to that from the plane to the second figure.