Derived illumination specifications

Abstract

This study is an evaluation of the Weston-Crouch system of computing illumination intensities for a specified per cent of maximum visual performance. The illumination intensities necessary for fastest reading of newsprint and of book print were determined experimentally by the author. These findings were then compared with the corresponding intensities recommended by the Weston-Crouch system. It was found that the computed foot candle levels are much higher than the levels found necessary for reading in the experimental situation. Possible reasons for the discrepancies between the computed and the experimentally determined intensities are discussed. (PsycInfo Database Record (c) 2025 APA, all rights reserved)