Artificial Light | Page 7

is often compelled by necessity to adopt the methods of
primitive beings. The rubbing of sticks is an emergency measure of the
master of woodcraft at the present time, and the production of fire in
this manner is the proud accomplishment or ambition of every Boy
Scout.
Where only such crude means of kindling fire were available it became
the custom in some cases to maintain a fire burning continuously in a
public place. Around this pyrtaneum the various civil, political, and
religious affairs were carried on by the light and warmth of the public
fire. Many quaint customs evolved, apparently, from this ancient
procedure.
The tinder-box of modern centuries doubtless originated in very early
times, for it is inconceivable that the earliest beings did not become
aware of the production of sparks when certain stones were struck
together. In the stone age, when human beings spent much of their time
chiseling implements and utensils from stone by means of tools of the
same substance, it appears certain that this means of producing fire was
ever apparent. Many of their sharp implements, such as knives and

arrow-heads, were made of quartz and similar material and it is likely
that the use of two pieces of quartz for producing a spark originated in
those remote periods. Alaskan and Aleutian tribes are known to have
employed two pieces of quartz covered with native sulphur. When
these were struck together with skill, excellent sparks were obtained.
Later, when iron and steel became available, the more modern
tinder-box was developed. An early application of the flint-and-steel
principle was made by certain Esquimo tribes who obtained fire by
striking a piece of quartz against a piece of iron pyrites. The latter is a
yellow sulphide of iron, of crystalline form, best known as "fool's
gold." Doubtless, the more primitive beings used dried grass, leaves,
and moss as inflammable material upon which the sparks were
showered. In later centuries the tinder-box was filled with charred grass,
linen, and paper. There was a long interval between the development of
fire-sticks and that of the tinder-box as measured by the progress of
civilization. During recent centuries ordinary brown paper soaked in
saltpeter and dried was utilized satisfactorily as an inflammable
material. Such devices have been employed in past ages in widely
separated regions of the earth. Elaborate specimens of tinder-boxes
from Jamaica, Japan, China, Europe, and various other countries are
now reposing in the collections in the possession of museums and of
individuals.
If the radiant energy from the sun is sufficiently concentrated upon
inflammable material, the latter will ignite. Such concentration may be
achieved by means of a convex lens or a concave mirror. This method
of producing fire does not antedate the more primitive methods such as
striking quartz or rubbing wooden sticks, because the materials
required are not readily found or prepared, but it is of very remote
origin. Aristophanes in his comedy "The Clouds," which is a satire
aimed at the science and philosophy of his period (488-385 B. C.),
mentions the "burning lens." Nearly every one is familiar with an
achievement attributed to Archimedes in which he destroyed the ships
at Syracuse by focusing the image of the sun upon them by means of a
concave mirror. The ancient Egyptians were proficient in the art of
glass-making, so it is likely that the "burning-glass" was employed by

them. Even a crude lens of glass will focus an image of the sun
sufficiently well to cause inflammable material to ignite.
The energy in sunlight varies enormously, even on clear days, because
the water-vapor in the atmosphere absorbs some of the radiant energy
emitted by the sun. This absorbed radiation is chiefly known as
infra-red energy, which does not arouse the sensation of light. When
the water-vapor content of the atmosphere is high, the sun, though it
may appear as bright to the eye, in reality is not as hot as it would be if
the water-vapor were not present. However, a fire may be kindled by
concentrating only the visible rays in sunlight because of the enormous
intensity of sunlight. A convex lens fashioned from ice by means of a
sharp-edged stone and finally shaped by melting the surfaces as they
are rubbed in the palms of the hands, will kindle a fire in highly
inflammable material if the sun is high and the atmosphere is fairly
clear. Burning-glasses are used to a considerable extent at the present
time in certain countries and it is reported that British soldiers were
supplied with them during the Boer War. Indicative of the predominant
use to which the glass lens was applied in the past is the employment of
the term "burning-glass" instead of lens in the scientific writings as late
as a century or two ago.
As civilization