Projection of spheres to a plane; optics of light and shadow
Overlapping shaded circles send rays through a common point to a vertical plane bearing a semicircular arc
At the left several overlapping circles or spheres, some of them shaded, send straight lines that converge toward a single point and then continue to a vertical plane carrying a semicircular arc at the right. The figure is lettered at the centres of the circles and at the point of convergence, and reads as a construction for the projection of light and shadow, or the intersection of visual rays, between bodies and a screen. A fainter version of the same construction lies below at the left, and blocks of Leonardo's mirror-writing along the bottom are not transcribed here; the Bibliothèque de l'Institut de France stamp is present.
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Rays from shaded spheres crossing to a plane
Overlapping circles at the left, partly shaded to suggest solid bodies and their shadows, throw straight lines that pinch through a common point and then spread to a vertical plane bearing a semicircular arc. The construction traces how light and shadow, or the images of the spheres, are cast onto a screen.
Lettered intersection of lines
The diagram is marked with letters at the centres of the circles and at the point where the lines cross, defining the geometry of the intersection. A fainter repeat of the whole construction is sketched below at the left.