When the method of opening the mine by a shaft is employed in these steep-pitching seams, the shaft is sunk to the lowest level, and the successive sets of gangways and breasts are laid off as the work progresses upwards; that is, the slope method of extending the lifts downwards is simply reversed. The method of mining by tunnel and drift, and by slope in the flat workings, is not different from the method already described for shafts. So soon as the drift, tunnel, or slope has extended far enough into the coal seam it becomes a gangway, chambers are laid off from it, and mining goes on in the familiar mode. Various modifications of the pillar and breast system are employed in the anthracite coal mines, but no system is in use which is radically different. In the “long wall system,” common in Great Britain, and used to some extent in the bituminous mines of Pennsylvania and the Western States, the process of cutting coal is carried on simultaneously along an extended face. The roof is allowed to fall, back of the workers, roads being preserved to the gangway, and the roof at the face is temporarily supported by an abundance of wooden props. The descriptions of underground workings that have now been given have, of necessity, been very general in their character. It is impossible, in a limited space, to describe the various methods and modifications of methods which are in use. No two mines, even in the same district, are worked exactly alike. Sometimes they differ widely in plan and operation. That system must be employed in each one which will best meet its peculiar requirements. There is large scope here for the play of inventive genius. There is scarcely a mine of any importance in the entire coal region in which one cannot find some new contrivance, some ingenious scheme, some masterpiece of invention devised to meet some special emergency which may have arisen for the first time in the history of mining. Yet the general features of all coal mining methods must of necessity be the same in underground workings. No one reasonably familiar with them could ever mistake a map of a coal mine for a map of anything else under the sun. CHAPTER IX. THE MINER AT WORK. The number of persons employed in a single mine in the anthracite regions varies from a dozen in the newest and smallest mines to seven hundred or eight hundred in the largest and busiest. The average would probably be between two hundred and three hundred. In the bituminous districts the average is not so large. First among those who go down into the mine is the mine boss, or, as he is sometimes called, the “inside boss.” It is his duty “to direct and generally supervise the whole working of the mine.” All the workmen are under his control, and everything is done in obedience to his orders. He reports to, and receives instructions from, the general superintendent of the mines.