Derivative shadow keeps the shape of the original shadow
A cross-shaped light makes a round body cast a cross-shaped shadow
The folio holds that a projected (derivative) shadow always conforms to the form of the original shadow on the body itself. A first figure sets screens and a central sphere to show that light in a cross ('crociale') form makes a spherically round opaque body cast a cross-shaped shadow, lettered a b c d e f, n g o t, m l S 9 K 7 x y. A second figure with three luminous bodies and one small opaque body demonstrates that a cast shadow can occur where there is no original shadow, and a tiny subsidiary sketch isolates the relation of light to its point of percussion.
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Derivative shadow conforms to the original shadow
The projected, or derivative, shadow always keeps conformity with the form of the original shadow. Its outline echoes the shape from which it is thrown.
Cross-shaped light makes a round body cast a cross shadow
Light issuing in a cross ('crociale') form causes an opaque body of spherical roundness to produce of itself a shadow of cross figure. The construction is lettered a b c d e f, n g o t, m l S 9 K 7 x y across its screens and central sphere.
A derivative shadow without any original shadow
With three luminous bodies and one small opaque body it is shown that many times a cast, derivative shadow can be found where there is no original shadow at all. The parts are marked h luminous m, f e g, and a b luminous c d.
Light and its point of percussion
A small subsidiary sketch labels only lume (light) and percussione, the point of impact where the ray strikes. It isolates the basic relation used throughout the folio.