Sentence Examples with the word optical illusion

MIRAGE (a French word, from mirer, to look at, se mirer, to be reflected), an optical illusion due to variations in the refractive index of the atmosphere.

The Rotunda, where are the ruins of the old saltpetre works; the Star Chamber, where the protrusion of white crystals through a coating of the black oxide of manganese creates an optical illusion of great beauty; the Chief City, where an area of 2 acres is covered by a vault 125 ft.