Fic. 85. Cutting away rock with a compressed-air drill in a Michigan copper mine.
Note how beams are used to support the roof and sides of galleries in mines.

CHAPTER NINE

THE MINING INDUSTRY

Minine differs from other means of primary production in three ways:
(1) There is no way of increasing the original supply of the
product.
(2) Production is restricted to a few localities.
(8) Until the rocks are actually examined in detail it is almost
impossible to tell where it will be profitable to carry on
operations.

Why mining is the robber industry. The mining industry takes
from the rocks vast stores of wealth which nature has deposited,
and which nature herself cannot renew for millions of years. For
this reason mining is sometimes called the ¢ robber industry.” When
man harvests a crop on a farm, the fertile soil still remains, and other
crops can be raised; if a forest is cut down, another may grow
in time; although many cattle are killed, the herd will increase in
number; fish also multiply freely, even though great quantities are
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