Abstract
The visual acuity is measured (in a way, described in a previous article: De Ingenieur 49, nr. 4, A 31, 1934) for objects illuminated by the following light-sources: mercury light, neon light, monochromatic Hg-light of 5461, 5770-5790 and 4358 A respectively, and neon light with a wavelength 6350 A. The visual acuity is highest mercury light, 5461 and 5770 - 5790 A; then follow sodium light, neon light 6350 A, complete neon light, white light and lastly light of 4358 A. The influence of a glaring light-source is studied with sodium light and with white light.