Part 24

Extent, interrupted, illusions of, 48

External image, 15, 17, 34

Eye, physiology, 13 position, 30 adjustments, 33 defects, 19

Fatigue, 128

Field, visual, effect of location in, 44

Figures, equivocal, 64

Filters, color, 214

Fluctuation of attention, 65, 106, 141, 164

Focusing, 14

Form of sky, apparent, 166

Fovea centralis, 22, 23, 139

Frames, picture, effect of wood grain, 190

Geometrical illusions, 44

Glare, 119

Grain of wood, apparent distortions due to, 190

Grecian art, 196

Growth and decay of color sensation, 131

Guttman, 175

Hallucination, 4, 72

Halo, 178

Haze, illusions, etc., 103, 166, 183 earth and high, 240

Helmholtz, 13, 74

Hering, 74 illusion of direction, 80

Hue and brightness, 125

Illusions, geometrical, 44 equivocal figures, 64 influence of angles, 76 of depth and distance, 102 irradiation and brightness contrast, 114 color, 124 light and shadows, 144 in nature, 164 in painting and decoration, 179 mirror, 205 camouflage, 210

Image after-, 24, 25, 59, 128, 129, 186 double, 37 external, 15, 17, 34 retinal, inversion of, 16 of airplane, size at various altitudes, 238

Indirect vision theory, Auerbach's, 100

Intaglio, 143