class="pginternal" tag="{http://www.w3.org/1999/xhtml}a">69
| 32. |
A reversible tetrahedron |
69 |
| 33. |
Reversible perspective of a group of rings or of a tube |
70 |
| 34. |
Schröder’s reversible staircase |
70 |
| 35. |
Thiéry’s figure |
71 |
| 36. |
Illustrating certain influences upon the apparent direction of vision. |
| |
By covering all but the eyes the latter appear to be drawn alike in both sketches |
73 |
| 37. |
Zöllner’s illusion of direction |
77 |
| 38. |
Parallel lines which do not appear so |
79 |
| 39. |
Wundt’s illusion of direction |
79 |
| 40. |
Hering’s illusion of direction |
80 |
| 41. |
Simple effect of angles |
81 |
| 42. |
The effect of two angles in tilting the horizontal lines |
83 |
| 43. |
The effect of crossed lines upon their respective apparent directions |
83 |
| 44. |
Another step toward the Zöllner illusion |
84 |
| 45. |
The two diagonals would meet on the left vertical line |
85 |
| 46. |
Poggendorff’s illusion. Which oblique line on the right is the prolongation of the oblique line on the left? |
85 |
| 47. |
A straight line appears to sag |
86 |
| 48. |
Distortions of contour due to contact with other contours |
87 |
| 49. |
An illusion of direction |
88 |
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