.

It must have taken a long course of experiments to determine what
proportions of each metal to use to make the best bronze. It is
interesting to know that these early workers had learned the proportions
of each to use, not varying a great deal from the results of modern
research--that is, from ten to twelve per cent of tin. Bronze relics,
no matter where obtained, whether in the Old or the New World, do
not widely depart from this standard, and such instances as do would
probably denote that the supply of tin became short. This uniformity of
composition would imply that the art of making bronze was discovered in
one place, from which it gradually spread over the globe.

This fact is a key to the culture of the Bronze Age. Widely separated
communities, destitute of a knowledge of metals, would instinctively
make use of stone. In this case uniformity of type would not imply
community of knowledge. But a knowledge of metals is altogether
different. It is wonder enough that one community should have hit on
the invention of bronze. The chance would be against its independent
discovery in widely separated areas. They would be more apt to chance
on the production of some other metal. Thus; tribes in the interior of
Africa are said to have passed direct from the Stone to the Iron Age, a
knowledge of bronze not having been carried to them.

We are thus able to form a true conception of the Bronze Age. It did
not prevail over the world at the same time. Indeed, as we shall
subsequently see, there is every reason to suppose it spread very
slowly, and that it still lingered in Central and Northern Europe long
after its use had been abandoned for that of iron in the South. Neither,
when it was first introduced, did it put a stop to the use of stone.
It was necessarily costly, and on its first appearance in a country,
brought hither by trade, could only be afforded by rich and powerful
chiefs and warriors. As time advanced, and they learned to make it
cheaper, and each country took up its separate manufacture, it would
gradually supersede stone. But bronze was never cheap enough to drive
out the use of stone altogether. This only occurred when the art of
working iron was discovered.

We shall learn that the knowledge of bronze, while a very important
and distinguishing phase of culture of the Bronze Age, was not its only
characteristic. It was distinguished by the arrival and spread of the
Aryan races, by a great extension of