Visual illusions, their causes, characteristics and applications (1922)
Luckiesh, Matthew, 1883- · New York, Van Nostrand · leaf 70
57 TYPES OF GEOMETRICAL ILLUSIONS at the horizon in a manner somewhat similar to the angle but it is difficult to imagine such an angle made by the vault of the sky and the earth's horizon. If Fig. 19. — Circles influenced by position within an angle. there were one in reality, it would not be seen… … Fig. 20. — Contrasting angles. being common to the inner and two bounding angles, the effect of contrast is very apparent, as seen in Fig. 20. In Fig. 57 are found examples of effects of lines con- trasted as to length.
Optical illusions
Internet Archive · Gerstein - University of Toronto · Public domain (published before 1931). Free to use for anything.
