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 the mountain, and great falls of rock like falling cities. You would be sure to scream with fright the first time you heard it. By and by, when the dust from an explosion has settled, the miners go back and find tons of broken up iron ore all ready to load into the ore cars. These are pulled up the shaft by cables, and sent down the railway track from twenty to a hundred miles to the lake. It is down hill all the way, a drop of ten to a hundred feet to the mile, so the little ore cars don't need an engine. They just roll along by themselves. The track runs out on a high bridge-like pier for half a mile, and over deep water. There men help the cars dump their loads into ore bins.

Ore ships steam right under these bins. The bottoms of the bins drop on hinges like doors, and the ore tumbles into the holds of the ships. The ships steam away over hundreds of miles of the great lakes and carry the ore to Chicago or to Cleveland, Ohio. From Cleveland most of the ore is sent by rail to Pittsburg, the greatest iron manufacturing city in the world.

To melt iron ores, coal and limestone are needed. The three things are not found together. The limestone and coal are around the lower lakes, and these are nearer the railroads and big markets for iron. The ores on the upper lake can be shipped cheaply. You see the cars run by their own weight to deep water, and vessels can carry things for less money than trains. So it costs very little to send ore from those mines to where there is coal and limestone.

The furnaces where iron is melted out of the ore, are tall towers of iron plates bolted together and lined thick with fire clays that will not melt. The furnaces are often as tall as a six or eight story building. They stand together in a group, each one plumed with black smoke and at night with smoky flames. A stranger coming into Chicago or Pittsburg by night, might think these cities had volcanoes from the glow of fire in the sky above the furnaces.

The inside of a blast furnace is the shape of a gigantic bottle turned upside down. An elevated railroad runs from the dumps of ore, coke and limestone in the vast yards to the tops of these furnaces, and from one to another. On a railed balcony at the top of each are men who see that the furnaces are properly filled. A car load of coke is dumped in, then limestone, then ore, making sandwiches of them. More material is put in, in the same order and amounts, until the furnace is filled. A fire is kindled at the bottom, below the small neck of the bottle. Soon the coke is on fire, a blast of warm dry air is forced through the furnace, and everything inside melts together