Evening Republican, Volume 22, Number 108, Rensselaer, Jasper County, 8 May 1919 — Testing the Eye. [ARTICLE]

Testing the Eye.

Lecturing on the “Effect on the Eye of Varying Degrees of Brightness and Contrast” before the Illuminating Engineering societv recently, Dr. James Kerr of the public health department of the London county council, referred to some effects which may be surprising. Having to examine long lists pf figures in black type, he tried to facilitate his task by drawing vertical and horizontal lines in red ink, but the different foeusing of the black and red strained his eye and gave him a headache, which did not trouble hiin when all the figures and lines were either black or red. Doctor Kerr quesr tions whether a target is more distinct when a brilliantly illuminated disk appears on a jet black background than when the surroundings were diffusely illuminated. , - ! . ..