King Coal by Upton Sinclair

These were the last words Hal spoke. They were obvious enough words, yet when he looked back upon the coincidence, it seemed to him a singular one. For while he was sitting there chatting, it happened that the poor underdogs inside the mountain were in the midst of one of those experiences which make the romance and terror of coal-mining. One of the boys who were employed underground, in violation of the child labour law, was in the act of bungling his task. He was a "spragger," whose duty it was to thrust a stick into the wheel of a loaded car to hold it; and he was a little chap, and the car was in motion when he made the attempt. It knocked him against the wall -- and so there was a load of coal rolling down grade, pursued too late by half a dozen men. Gathering momentum, it whirled round a curve and flew from the track, crashing into timbers and knocking them loose. With the timbers came a shower of coal-dust, accumulated for decades in these old workings; and at the same time came an electric light wire, which, as it touched the car, produced a spark.

And so it was that Hal, chatting with the marshal, suddenly felt, rather than heard, a deafening roar; he felt the air about him turn into a living thing which struck him a mighty blow, hurling him flat upon the floor. The windows of the room crashed inward upon him in a shower of glass, and the plaster of the ceiling came down on his head in another shower.