Brightnesses in visual field at borderline between comfort and discomfort (BCD). Paper presented at the National Technical Conference of the Illuminating Engineering Society, September 20-23, 1949, French Lick, Indiana, U.S.A.

This paper presents the results of an extensive series of researches of the effects of sources of brightness in the visual field upon comfort and discomfort. The basic factors and their relationship are discussed which affect the visual sensation. By combining the effects of the modifying factors with the basic relationships, it has been possible to devise a monogram and disk calculator which simplify the determination of the brightness conditions which should produce an average BCD sensation or BCD brightness. A discussion on this paper is added.