Seeing Not Always Believing.

New Zealand Graphic, Volume XXXVI, Issue 3, 20 January 1906, Page 24

Seeing Not Always Believing.

Despite the proverb which tells us that “seeing is believing,” we ought not to have implicit faith in our visual organs, for the fact is that they very often deceive us. A ring of fire is imide by the swinging round of a red-hot end of burning stick. We kuow, however, that there is no ring of lire, though the eyes i-an detect no break in the continuity. And were it not for this phenomenon of vision fireworks would have little attraction, because the fieiy tail of the rocket would be absent, and “set pieces” would exhibit but a shower of sparks. The illusion is due to what, is known as the “persistence of visual impressions on the retina”—that is to say, an object placed before the eye and suddenly removed i-s seen for a certain length of time after its removal. rhe relative brightness of objects considerably affects their apparent size. 1 litis, if two equal-sized wafers.— one black ami the other white—be placed side by side, the white dise will appear to be much larger than the black. Tin' illusory effect of colours one upon another arc very interesting. Red and green together, or blue and orange, or violet and yellow, heighten the colour of both. Blue placed near yellow acquires a more violet hue, whilst the yellow inclines towards orange colour. Deceptions are also produced by re-

fleet ors or other optical contrivances, Kiich as the effect known as “Pepper’s Ghost”; and the scenic effects upon the stage largely depend upon an exaggeration of the results of perspective.