Perception on the Road When Visibility Is Low

PERCEPTION ON THE ROAD WHEN VISIBILITY IS LOW We should like to pay tribute to the memory of Dr. Pieter Johannes Bouma, born in Amsterdam on 14th April 1908, who died at Eindhoven on 19th January 1947. Bouma was connected with the Philips Laboratory in Eindhoven as an assistant from 1928 until 1930 and as a research physicist from 1933 until his death. From 1930 until1933 he studied at Utrecht, where in November 1933 under Ornstein he received his degree on his thesis: "Beitrag ZUl' Dynamik del' flüssigen Kristalle", Bouma specialized on the theory of illumination and colorimetry, in which fields various publications from his pen have appeared in Physica and in the Proceedings of the "Kon. Ned. Akad. van Wetenschappen". He also wrote many articles for the Philips Technical Review. Furthermore he rendered valuable services to the Netherlands Foundation for Illumination Technology (Ned. Stichting' v. Verlichtingskunde). Since 1940 Bouma had been suffering from a disorder of the central nervous system, which, though it fortunately did not affect his acute intellect, made speaking and writing more and more difficult for him. Nevertheless, between September 1944 and April 1945he was able to complete the manuscript ofhis book "Colour Stimuli and Colour Sensations", as well as three other publications. During 1946 his strength failed him, but he still had the satisfaction of seeing his book in print (it was published in November 1946, and a review of it is given on page 159 of this number). The following article is a praotically unaltered version of a lecture given by B 0 um a at Utrecht in 1940 for a Vacational Course on "Road and Street Lighting".