COAL AND IRON 191. The old way of making iron.— No one knows how long ago it was that men learned how to roast iron ore in a hot fire until it was melted and the iron ran out, ready to be pounded on the anvil as we see the blacksmith pounding and shap ing his iron to-day. Long before the time of Christ, white men, yellow men, and black men knew how to make iron. Iron spear heads and axes were a great improve ment over the tools of stone that men had used before they got iron. Learning how to make iron was the greatest invention of ancient man. These early people made a fire of charcoal (partly burned wood) on a little hearth or forge, and fanned it hard to make it very hot. In this fire they melted their iron ore. It took much hard work to make a little iron.
Men were still making iron with these charcoal fires when our great-grandfathers were born, and there were stone forges, or furnaces, in the woods in every state on the Atlantic Coast. The most of them were in Pennsylvania and New Jersey, where iron was plentiful. Soon after the railroads came (about 1820), somebody learned how to make iron with the hard coal found in eastern Pennsylvania near the cities of Scranton and Wilkes-Barre.
After a few years, some one discovered a way to partly burn soft coal and turn it into coke to use instead of charcoal for the smelting of iron ore. There is so much more soft coal than there is hard coal, and soft coal is so much easier to dig, that many of the iron makers moved over to western Pennsylvania. There layers of soft coal stick out of the rocks on the hillsides, and county after county has layers of coal under it. There are now hundreds of coal mines where men are digging out this coal.
192. Pittsburgh, an iron em Pennsylvania is a plateau, where many streams have cut narrow valleys. There fore most of the land is very hilly. In such a country the railroads have to follow the streams. If you look at the map (Fig. 198), you will see how the railroads of western Pennsylvania, as they follow the streams, must come together at Pittsburgh. This
junction point (Fig. 195) is in the midst of the coal fields, and iron ore is found near by; thus this section early became an easy place in which to make iron and steel, and things that are made of iron and steel.
About 1884 it was found that the very rich iron ore from the mines near Duluth (Sec. 101) could be brought down the lakes to Cleveland, taken to Pittsburgh by train, and made into iron more cheaply than if the poorer ores of Pennsylvania were used. As a result, big lake steamers and more railroads were built. New iron mines were opened near Lake Superior, and more coke ovens were made in Pennsyl vania. Now millions and millions of tons of iron ore come down the lakes every year to Pittsburgh, the greatest iron center in the world.
. 193. The new way of making iron.—An iron furnace is ten times a's high as a room in an ordinary dwelling-house, and is full of roaring fire from top to bot tom. Its flames light up the sky at night for miles around. Little car loads of coke, ore, and limestone to make the ore melt easily, are dumped into the furnace every few hours day and night, weekdays and Sundays, for months and months. The fire in the furnaces is never allowed to go out, except for repairs; for it takes days to start a furnace, once it stops.
Every few hours a hole is opened in the bottom of the furnace and the melted iron runs out. This is led away down a channel in a sand floor and allowed to run off into little pools where it cools in chunks, each about as big as three or four bricks. These pieces are called pigs. Sometimes the melted iron, still hot, is taken to the neigh boring steel mills, heated more, and changed into steel. After this it is poured into big moulds and cooled a little. Then, while still white-hot, it is rolled by big rollers (Fig. 199) into bars, rods, rails for railroads and trolley lines, plates for boilers and ships, parts for steel bridges and steel buildings, and sheets for tin plate.