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