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"An optical toy consisting of a vertical cylindrical mirror which gives a correct image of a distorted picture drawn at the base on a plane at right angles to axis of the mirror."-Whitney, 1902

Anamorphoscope

"An optical toy consisting of a vertical cylindrical mirror which gives a correct image of a distorted…

"A method of drawing which gives a distorted image of the object represented when it is viewed from directly or nearly so, but a natural image when it is viewed from a certain point, is reflected by a curved mirror, or is seen through a polyhedron."-Whitney, 1902

Anamorphosis

"A method of drawing which gives a distorted image of the object represented when it is viewed from…

Optical illusion.

Helmholtz's Squares

Optical illusion.

Optical Illusion

Illusion, Von Recklinghausen's Illusion

Optical Illusion

The Zöllner illusion is a classic optical illusion named after its discoverer, German astrophysicist Johann Karl Friedrich Zöllner. In this figure the black lines seem to be unparallel, but in reality they are parallel. The shorter lines are on an angle to the longer lines. This angle helps to create the impression that one end of the longer lines is nearer to us than the other end. This is very similar to the way the Wundt illusion appears. It may be that the Zöllner illusion is caused by this impression of depth.

Zollner Illusion

The Zöllner illusion is a classic optical illusion named after its discoverer, German astrophysicist…