BLAST FURNACES OF THE CARNEGIE STEEL COMPANY
Perhaps your knife blade is made of steel manufactured in one of the huge factories in this busy district. The car tracks of your town, the street-car wheels, and the great locomotives, to say nothing of the heavy steel beams and girders of your fireproof buildings, may all be products of this mighty workshop.
MINERS AT WORK
IN A MODERN COAL MINE
Pittsburgh coal is used all over the country. The near-by mines form a great underground city, whose dark passageways, far below the surface of the earth, are lighted by tiny electric lights. More than fifteen thousand men find employment in this weird city. Day after day the brave miners go down into the mines, never sure that they will see the sunlight again, for many are the perils of mining. Who has not read of the terrible disasters caused by suffocation from fire damp, by flood, the falling of walls, or the explosion of coal dust? Small particles of coal dust are constantly floating in the mines, and much is stirred up by the cars used to carry the coal to the outside world. A tiny spark may ignite this dust and cause it to explode with terrific force. Sometimes even the presence of much oxygen in the air will make the dust explode, tearing down great blocks of coal which bury the poor miners or stop up the passageways so that there is no escape unless the victims are dug out before they die.
THE ENTRANCE TO A COAL MINE
