already made by the Geological Survey, that better means of safeguarding
the lives of miners will be found, and that the death rate from mine
accidents will soon show a marked reduction.

Other statistics collected by the Geological Survey show that, to the
close of 1907, nearly 7,000,000,000 tons of coal had been mined in the
United States, and it is estimated that for every ton mined nearly a ton
has been wasted, 3,500,000,000 tons being left in the ground or thrown
on the dump as of a grade too low for commercial use. To the close of
1907 the production represents an exhaustion of somewhat more than
10,000,000,000 tons of coal. It has been estimated that if the
production continues to increase, from the present annual output of
approximately 415,000,000 tons, at the rate which has prevailed during
the last fifty years, the greater part of the more accessible coal
supply will be exhausted before the middle of the next century.

The Forest Service estimates that, at the present rate of consumption,
renewals of growth not being taken into account, the timber supply will
be exhausted within the next quarter of a century. It is desirable,
therefore, that all information possible be gained regarding the most
suitable substitutes for wood for building and engineering construction,
such as iron, stone, clay products, concrete, etc., and that the minimum
proportion in which these materials should be used for a given purpose,
be ascertained. Exhaustion, by use in engineering and building
construction, applies not only to the iron ore, clay, and cement-making
materials, but, in larger ratio, to the fuel essential to rendering
these substances available for materials of construction. Incidentally,
investigations into the waste of structural materials have developed the
fact that the destructive losses, due to fires in combustible buildings,
amount to more than $200,000,000 per annum. A sum even greater than this