ountry; in 1890, 320 pounds; in 1900, 390 pounds, and in 1907,
696 pounds. According to the rule of increase, by 1916 we shall be using
104,000,000 tons a year; by 1925, 208,000,000, and by 1934, 416,000,000
tons, and if the same rate of increase should continue, by 1940 we
should have required for our use in the meantime, six billion tons. But
we have less than five billion tons of what is now classed as available
ore, which means that before that time (when the school-boys of to-day
are business men) we should have exhausted all our good and cheap ore,
and be obliged to depend only on the low-grade ores, the cost of which
will be very great.

Unlike coal, the forests, and the soil, there is no great and entirely
useless waste of iron. But the uses of iron are so many and so varied,
and the supply of high-grade ores which can be cheaply mined is so small
in proportion to the needs of the future, that we should in all ways
lessen the drain on it by substituting other cheaper and more plentiful
materials when possible.

The chief use of iron is for the carrying of freight. Here are some
figures given by Mr. Carnegie. Moving one thousand tons of freight by
rail requires an eighty-ton locomotive and twenty-five twenty-ton steel
cars, or five hundred and eighty tons of iron and steel to draw it
over--say an average of ten miles of double track with switches, frogs,
spikes, etc., which will weigh more than four hundred tons. Thus we see
that to move a thousand tons of freight requires the use of an equal
weight of iron. The same freight may be moved by water by means of from
one hundred to two hundred and fifty tons of metal, so that if freight
were sent by water instead of by rail the amount of iron needed for this
service would be reduced at least three-fourths, the amount of coal
would be reduced not less than half, and at the same time the coal used
in extra smelting would be saved. No single step open to us to-day would
do more to check the drain on both iron and coal than the use of our
rivers for carrying heavy freight.

The next great use of iron is for buildings and bridges. The greatly
increasing use of cement and concrete is reducing this and will reduce
it still further. Cement is made from slag, or the refuse of iron
ore--the clays and shales--and the cost of this valuable product is
little more than the former cost of piling it away. By making the
useless slag into cement the cost of iron production is lowere