Every shadowy body lies between a dark and a bright pyramid
Propositions [732] and [733] on shadow width and the paired pyramids of a window's light
Two lettered propositions are set out. [732] holds that any shadow which grows wider with distance than its cause has its exterior lines joining together between the light and the shadowy body, proved by a window a b without partition, where the luminous air seen from a reaches d and that from b reaches c, the lines crossing at m. [733] states that every shadowy body lies between two pyramids, one dark and one luminous, of which only one is seen, and this happens only when light enters through a window. A diagram shows the window line a b beneath a labelled horizon (Ponente / Levante), with a small sphere and crossing pyramidal lines meeting at M above a hatched shaded rectangle.
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Shadow's outer lines join between the light and the body [732]
Every shadow that grows wider with distance than its cause has its exterior lines joining together between the light and the shadowy body. If a b is a window without any partition, the luminous air on the right at a is seen from the left at d, and the air on the left at b illuminates from the right at c, and these lines intersect at the point m.
Two pyramids, one dark and one luminous [733]
Every shadowy body is found between two pyramids, one dark and the other luminous; one is seen and the other not, and this happens only when the light enters through a window. Take it that a b is the window and r is the shadowy body.
Window, sphere, and crossing pyramids
The diagram carries a horizon line marked Ponente (west) and Levante (east) with the window a b, a small circle for the shadowy body marked m, and straight lines crossing at a lower point M to form paired pyramids above a hatched shaded rectangle, with points o, i, d and c marked.