conditions of use, waste, and increase to continue, the coal
supply will be exhausted by the year 2015 A. D., but taking into account
the probable improvements in its use, the year 2027 A. D. is estimated
as the time when the present coal fields will be exhausted, and the
middle of that century as the time when all coal fields in the United
States will be gone.

This true story well illustrates the need of conservation and the folly
of careless waste. High in the hills of the Pittsburg region a thick
bed of excellent coal was found by the early settlers. It was impossible
for them to build roads up the steep cliffs, so some method of getting
the coal down to the valleys had to be devised. Buffaloes roamed the
western plains in countless millions, and were so abundant about
Pittsburg that the supply seemed inexhaustible. So the pioneers killed
the buffaloes, filled each skin with a few bushels of coal, sewed it up,
and tumbled it down the mountain side.

This was the way they marketed their coal--by destroying their
buffaloes. For many years no one dreamed that there was any end to the
supply of buffaloes. And so both east and west they were killed for
their skins, which sold for a few cents, for their horns, for a supply
of steak, or for mere sport; and then one day people woke up to find
that the buffalo had disappeared, not in one settlement only, as they
had supposed, but everywhere. There are a few remaining, carefully cared
for by the government. They are among our most valued possessions, and
yet only a few years ago they were destroyed, wasted, by millions.

This passing of the buffalo, the skins of which, as common then as
burlap bags are now, were used to market our first coal, carries with it
a deep lesson as to what will happen to the coal itself, even within
the present century, unless our people awake to the consequence of what
they are doing and make a determined effort to stop all unnecessary
waste.

Let us see where and how these wastes occur. The first serious loss of
our coal occurs at the mines. There are three great wastes in mining.

(1) A coal bed is not made up entirely of pure coal, especially if it be
very thick. Sometimes there are layers of shale or clay, which makes a
large amount of ash. This can never be sold as regular marketable coal;
but it is rich in carbon, and much of it might be used if it could be
marketed near the mines and sold as low-grade coal. In the past there
has been al