As a night-light in a bed-room or in a
room habitually dark, the application has been found quite effectual, a
very small proportion of the surface rendered phosphorescent affording
sufficient light for moving about the room, or for fixing upon and
selecting an article in the midst of a number of complicated scientific
instruments or other objects.
The invention may also be applied to private and public buildings in
cases where it would be economical and advantageous to maintain for a
short time a waning or twilight, so as to obviate the necessity for
lighting earlier the gas or other artificial light. It may also be
used in powder-mills and stores of powder, and in other cases where
combustion or heat would be a constant source of danger, and generally
for all purposes of artificial light where it is applicable.
In order to produce and maintain the phosphorescent light, full sunshine
is not necessary, but, on the contrary, is undesirable. The illumination
is best started by leaving the article or surface exposed for a short
time to ordinary daylight or even artificial light, which need not be
strong in order to make the illumination continue for many hours, even
twenty hours, without, the necessity of renewed exposure.
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