artificial daylight, there are vast fields of lighting where a less
accurate daylight quality is necessary. The average eyes are not
sufficiently skilled for the finest discrimination of colors and
therefore the Mazda "daylight" lamp supplies the less exacting
requirements of color matching. It is a compromise between quality and
efficiency of light and serves the purpose so well that millions of
these lamps have found applications in stores, offices, and industries.
In order to make an accurate artificial north skylight for color-work by
means of colored glass, from 75 to 85 per cent. of the light from a
tungsten lamp must be filtered out. This absorption in a broad sense
increases the efficiency of the light, for the fraction that remains is
now satisfactory, whereas the original light is virtually useless for
accurate color-discrimination. About one third of the original light is
absorbed by the bulb of the tungsten "daylight" lamp, with a resultant
light which is an approximation to average daylight.

Old illuminants such as that emitted by the candle and oil-lamp were
used for centuries in interiors. All these illuminants were of a warm
yellow color. Even the earlier modern illuminants were not very
different in color, so it is not surprising that there is a deeply
rooted desire for artificial light in the home and in similar interiors
of a warm yellow color simulating that of old illuminants. The
psychological effect of warmth and cheerfulness due to such illuminants
or colors is well established. Artificial light in the home symbolizes
independence of nature and protection from the elements and there is a
firm desire to counteract the increasing whiteness of modern illuminants
by means of shades of a warm tint. The white light is excellent for the
kitchen, laundry, and bath-room, and for reading-lamps, but the warm
yellow light is best suited for making cozy and cheerful the environment
of the interiors in which mankind relaxes. An illuminant of this
character can be obtained efficiently by using a properly tinted bulb on
tungsten filament lamps. By absorbing about one fourth to one third of
the light (depending upon the temperature of the filament) the color of
the candle flame may be simulated by means of a tungsten filament lamp.
Some persons are still using the carbon-filament lamp despite its low
efficiency, because they desire to retain the warmth of tint of the
older illuminants. However, light from a tung