Mines were only held up by wooden beams, and the sheer weight of the ground above a mined coal seam led to many pit collapses.
A report on deaths in coal mines to Parliament gave a list of ways miners could be killed: falling down a mine shaft, being hit by falling coal, being crushed to death in collapse, explosions, suffocation due to poisonous gas leaks, and being run over by a tram carrying dug coal.