ore-hauling road. The ore
is therefore carried a distance varying from one thousand to one
thousand five hundred miles for less than it could be loaded, on cars
hauled one-tenth that distance by rail, and unloaded.

[Illustration: STEEL MANUFACTURE--ORE DOCKS]

At the south shore of Lake Erie, the ore meets the coke from western
Pennsylvania and coal from the Ohio coal-fields, and as a result new
centres of iron and steel manufacture have grown up along this line of
"least resistance." The ore is unloaded at the docks by means of
mechanical scoops and shovels. So cheaply and quickly is it mined and
transported that it is delivered to the smelteries at a cost varying
from $1.75 to $3.25 per ton.

[Illustration: LAKE SUPERIOR IRON ORE FIELDS]

There are three forms in which iron is used--cast iron, wrought iron,
and steel. Cast iron is crystalline and brittle. The product as it comes
from the blast furnace is called pig-iron. In making such commodities as
stoves, and articles that do not require great strength, the pig-iron is
again melted and cast into moulds which give them the required shape.
Cast iron contains from one to five per cent. of carbon.

Wrought iron is malleable, ductile, and very flexible; when pure it is
also very soft. It is prepared by melting pig-iron in furnaces having
such a shape that the molten metal can be stirred or "puddled" in
contact with the air. By this means the carbon is burnt out, and while
still at a white heat the pasty iron is kneaded or "wrought," in order
to expel other impurities.

Steel is a form of iron which is thought to contain a chemical compound
of iron with carbon. It is stronger than iron and finer in grain.
Formerly, steel was made by packing bars of pure iron in charcoal
powder, the whole being enclosed in clay retorts that were heated to
whiteness for about three days. The product obtained by this method is
known as cementation steel. It is still used in the manufacture of
cutlery, tools, and fine machinery; it is likewise very expensive. In
smelting certain ores it is easy to burn out the carbon in open
furnaces, and "open-hearth" steel is an important factor.

Just about the beginning of the Civil War, when the railways of the
United States were taxed beyond their capacity to carry the produce of
the country, it became apparent that something more durable than iron
must be used for rails. The locomotives, then weighing from twenty-five
to thirty-five tons each