Color Temperature Classification of Natural and Artificial Illuminants

This paper discusses the need for a quality rating of artificial light sources on the basis of color temperature and presents on two scales a large number of color temperature values for sunlight and daylight, together with the measurements on over thirty glasses which with gas-filled tungsten filament lamps will result in a range in apparent color temperatures from 2100 degrees absolute to 30,000 degrees absolute. A new instrument is illustrated for color temperature determinations. Reference is made to the quality spread in natural daylight with the means for producing a corresponding range in artificial daylighting accessories, and the various color of light qualities for particular color work are discussed.