Reflections of the sun on waves and the angle of vision
Why images of the sun grow fewer and larger, and equal visual angles look equal
The sheet continues Leonardo's study of the sun mirrored on moving water: radiant bursts at the top show sunlight scattered across waves, and he reasons that the nearer to the eye the reflecting waves are, the fewer but larger the images of the sun become. A run of triangular vision-pyramid diagrams with an eye at the apex develops the geometry of the visual angle, restating that a thing appears larger when it sends its likeness to the eye under a greater angle, and that unequal magnitudes seen under the same angle look equal. He heads the theme 'the science of the shadowed, the illuminated and the illuminating,' and a further figure notes that within a shadow no part integrally sees the whole body of the sun.
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Nearer waves give fewer, larger images of the sun (a)
The images of the sun on the waves are fewer in number the nearer to the eye the waves that display them are, and the closer those reflected images lie, the more they grow in size and shrink in number.
The whole pyramid and the sun of one width (a b c)
So remote from the eye that it shrinks to the eye's size, the far body would be seen wholly lit like the stars and moon; the eye a sees the whole pyramid a b c together with the sun as one and the same width.
No part fully sees the body of the sun
In the sun-earth-shadow figure Leonardo notes that within the shaded region there is no part that integrally sees the whole body of the sun. This belongs to his 'science of the shadowed, illuminated and illuminating.'
A greater angle makes a thing look larger (b a, d c)
That thing will appear larger which sends its likeness to the eye under a greater angle. A double-triangle figure demonstrates the principle.
Equal angles make unequal sizes look equal
All visible species that reach the eye under one and the same angle appear equal to one another, even though they are of unequal magnitudes; the proof shows that the larger space b d and the much smaller space h i come to the eye through the same angle.