As they made their way along, the under-viewer showed him a fault in the coal seam, and explained what it was. Coal seams generally run in a parallel position with the various other strata for a considerable distance, when, all at once, they abruptly terminate. This is marked as plainly as if a wall had been built up at the end of the seam. Thus, while on one side of the wall there is a thick seam of coal, on the other there is a mass of rock. This break or fault was caused at some remote period of the world’s history by an internal convulsion. It is known, however, that the seam will again be found, either at a higher or lower level than the one first worked. To reach the seam a tunnel is driven right through the rock, when sooner or later the seam is discovered. In the present fault, a tunnel had been run through the solid rock for fifty feet in length; and they might afterwards have to follow up the seam, extending perhaps half-a-mile, or even a mile, for the whole of which length a gallery would have to be cut, from which, side workings would extend on either side. So accurately did Mark note all he saw, that on his return home he was able to draw out a plan of the mine, with which the under-viewer was so pleased, that he took it to the manager.
“This boy deserves encouragement. We must see what can be done for him!” was the remark. Shortly after this, great improvements were introduced into the mine. Fresh shafts were sunk, for affording better ventilation, and for more rapidly getting the coal to the surface. Near them, engines of great power were placed to perform the various operations required. An endless wire rope was made to run from the shafts to the extreme end of the gallery, kept revolving by a steam-engine down in the mine. The man walking ahead of the leading waggon, to which is secured a pair of iron tongs, grips hold by them of this endless rope, which thus drags on his waggons without any labour on his part, towards the shaft, up which the coals are to be carried to the surface. The chief gallery was divided by a wall down the centre, with openings at intervals of twenty yards or so, to enable persons to pass through. There were also niches on either side, where he could stand while a train was passing. On one side of the gallery the full trains ran along on rails from the workings to the shaft; on the other side the empty waggons returned to the workings to be filled. For the purpose of better ventilating the mine, an enormous fan, forty feet in diameter, formed like the paddle-wheels of a steam-ship, and kept constantly revolving by steam-power, was placed over a shaft sunk for that sole object. The suction caused by the enormous paddles drew up all the foul air and noxious vapours from the whole of the mine, and at the same time drew in from another shaft, more than a mile distant, a current of fresh air, amounting from 70,000 to 80,000 feet per minute, thus doing the work of a furnace far more effectually, and at much less cost.
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