n account of the fact that the Stone Era of man occurred at
different times in different tribes. Thus the inhabitants of North
America were in the Stone Age less than two centuries ago, while some
of the inhabitants of the South Sea Islands are in the Stone Age during
the present century. It is quite remarkable that the use of stone
implements was universal to all tribes and nations at some period of
their existence.

After the long use of stone, man gradually became acquainted with some
of the metals, and subsequently discovered the method of combining
copper with tin and other alloys to form bronze, which material, to a
large extent, added to the implements already in use. The Bronze Age
is the most hypothetical of all these divisions, as it does not appear
to have been as universal as the Stone, on account of the difficulty of
obtaining metals. The use of copper by the Indians of the Lake
Superior region was a very marked epoch in their development, and
corresponds to the Bronze Age of other nations, although their
advancement in other particulars appears to be less than that of other
tribes of European origin which used bronze freely. Bronze implements
have been found in great plenty in Scandinavia and Peru, and to a
limited extent in North America. They certainly mark a stage of
progress in advance of that of the inhabitants of the Stone Age.
Bronze {37} was the chief metal for implements throughout the early
civilization of Europe.

Following the age of bronze is the Iron Age, in which the advancement
of man is especially marked. The bronze implements were at first
supplemented in their use by those of iron. But gradually iron
implements superseded the bronze. The Iron Age still is with us.
Possibly it has not yet reached its highest point. Considering the
great structures built of iron, and the excessive use of iron in
machinery, implements, and furniture, it is easy to realize that we are
yet in this great period. Though we continue to use stone more than
the ancients and more bronze for decoration and ornament than they, yet
both are subordinate to the use of iron. General as the above
classification is, it helps in an indefinite way to give us a central
idea of progress and to mark off, somewhat indefinitely, periods of
development.

_The Development of Art_.--Utility was the great purpose underlying the
foundation of the industrial arts. The stone axe, or celt, was first
made for a distinct s