Reflected light and the binocular view of two equal objects
How reflected light weakens with its source, with a lettered diagram, and why the farther of two equal objects can look larger.
The page finishes the paper-swatch method for matching colours in sunlight, then gives a chapter on reflected light: the less luminous an illuminated thing is than its source, the weaker its reflected part, and the nearer a surface lies to the illuminator the more it is lit. A pen diagram labels a luminous body at the left and an illuminated body at the right with the letters a, b, d, c, showing how the ratio of b c to b a governs the illumination of a d against d c. A second chapter and small diagram on perspective note that of two equal objects seen with both eyes, each narrower than the gap between the eyes, the farther appears the larger, the pyramids a c and d b embracing the two objects.
On this page
Reflected light weakens with its source
By as much as an illuminated thing is less luminous than its illuminator, by so much its reflected part is less luminous than the illuminated part, and a surface is most lit where nearest the illuminator. As much as b c enters into b a, so much more is a d illuminated than d c; and the more a wall is lit, the darker its shadows appear.
Two equal objects seen with both eyes
When two equal objects, each by itself narrower than the interval between the eyes' lights, are seen with both eyes, the second appears larger than the first. The pyramid a c embraces the first object, and the pyramid d b embraces the second object.