Appearance of the chambers. The miners, when they branch off from the main shaft or avenue, leave pillars of coal about eighteen feet square, to support the roof or mass above. These huge pillars were crushed by the great weight upon them, in the accident recorded.

chambers

Appearance of the chambers. The miners, when they branch off from the main shaft or avenue, leave pillars…

Cars entering the mines.

mining cars

Cars entering the mines.