（解説文要約）
圧縮空気の力で動くエアーピックという機械で、
スコップで運べない石炭の塊を砕いている様子を描いたものです。
先端を石炭に押し付け、砕いていきます。
The miner in this painting was crushing a huge coal lump into small pieces to be able to carry it out from the pit.
The machine he was using, called an Air Pick, was generated with compressed air.
The lump was crumbled by pressing the tip of this machine against it.