red

red white d a – c -b. To the left of the preceding figure, luminous and opaque bodies, with: qo-S-tc-pra-b-rn

qo-S-tc-pra-b-rn

m - e a - n -b-c-o-S. Operation of the compound shadow. The operations of compound shadows are always of contrary motions. That is, if the meeting of the luminous rays is touched by an opaque body before they reach their intersection, all the shadows of that body, breaker of the upper ray, will show themselves beyond that intersection in the striking of the lower ray; and just as the upper ray becomes the lower after the intersection, so the motions the opaque body makes within that upper ray will show themselves of contrary motion after that intersection. And this will be shown in the striking of the compound shadow upon the pavement, or on the wall struck by the sun or another luminous body. But if the luminous ray is impeded by an opaque body somewhat after its intersection, then the striking of the derivative shadow of the opaque body will make a motion similar to the motion of its opaque body. And if such rays are impeded at the very site of their intersection, then the shadows of the opaque body will be two, and will move with contrary motions one to the other before they come to union. The compound derivative shadow is the cause that the striking of the solar ray, passing through any sort of angle, does not imprint those angles but portions of circles, so much the greater or smaller as such impressions are more remote from or near to those angles.

If the marble should take ten years, I do not wish to wait for my payment to pass beyond the term of the completion of my work.

Weapons for shooting. Of the utility of shadows. Of the motion of shadows. Of the figure of shadows. Of quality. Of quantity. Of boundaries. Of simple shadow. Of compound shadow. Of decomposed shadow. Of darkness. Of light. Of light penetrating through various shapes of apertures. Of light passed through various numbers of apertures. Of the composition of several luminous rays. Whether it is possible that from one same luminous source rays may issue that penetrate one within another. Whether from one light, or through some aperture, parallel rays may penetrate.

d a -c b. The thing moved within the rays, before their intersection, casts a shadow of contrary motion after the intersection of those rays.

How the eye does not discern the shapes of bodies within their boundaries except by means of shadows and lights; and many are the sciences that would be nothing without the science of these shadows and light, such as painting, sculpture, astronomy, and in great part perspective and the like. It is proved that the sculptor cannot work without the aid of shadows and lights, for without such shadows and lights the sculpted material would remain all of one colour. And by the ninth of this it is proved that a flat surface, illuminated by an equal light, does not vary in any part the brightness or darkness of its natural colour, and by this equality of colour the evenness of the plane of such a surface is proved. It follows, then, that if the sculpted material were not clothed in such shadows and lights as the reliefs of the muscles and the hollows between those reliefs require, such a sculptor would not continually see his work as the work he is carving requires, and such work made by day would be almost as if it had been wrought in the dark of night. Of painting. But painting, by means of such shadows and lights, upon flat surfaces makes the concave and raised places appear separated one from another with various distances and by diverse aspects, and so on.