equipments were devised for portability. This mobile apparatus was
utilized against enemy aircraft and in various other ways. Small
hand-lamps are used to send out a pencil of light as directed by a pair
of sights and the code is flashed by means of a trigger. Raiding-parties
are no longer concealed by the curtain of darkness, for rockets and
star-shells are used to illuminate large areas. Flares sent upward to
drift slowly downward supported by parachutes saved and cost many lives
during the recent war. Rockets are used by ships in distress and also by
beleaguered troops.

Experiments are being prosecuted to ascertain the possibilities of
artificial light in the forcing of plant-growth, and even chickens are
made to work longer hours by its use.

Artificial light is now modified in color or spectral character to meet
many requirements. Daylight has been reproduced in spectral quality so
that certain processes requiring accurate discrimination of color are
now prosecuted twenty-four hours a day under artificial daylight.
Colored light is made of the correct quality which does not affect
photographic plates of various sensibilities. Monochromatic light is
utilized in photo-micrography for the best rendition of detail.
Light-waves have been utilized as standards of length because they are
invariable and fundamental. Numerous other interesting adaptations of
artificial light are in daily use.

This is in reality the age of artificial light, for mankind has not only
become independent of daylight in certain respects, but has improved
upon natural light. The controllability of artificial light makes it
superior to natural light in many ways. In fact, uses have been made of
artificial light which are impossible with natural light. Light-sources