Evening Republican, Volume 22, Number 99, Rensselaer, Jasper County, 28 April 1919 — Illusion Used as a Test of Correctness of Vision [ARTICLE]

Illusion Used as a Test of Correctness of Vision

In parlor physics an illusion is sometimes demonstrated as follows: a sheet of newspaper is rolled up to make a tube three feet long which is held in the right hand tn front of the right eye which is focused through the tube upon some distant object. The left eye is directed upon the palm of the left hand, which is held against the tube and near its peripheral end. The two eye pictures are fused in the brain so that the right eye appears to see its objective through a hole in the left hand. This trick is of value in testing the eyes. If the hole is seen in the middle of the hand binocular vision is perfect. If seen on the right side there is exaggerated convergence; if on the left side there is a divergence.