Stock Photo: Polish miners at Wielleczka salt mine descending the shaft in a group of six each sitting in a loop of rope, with all six loops attached to a single rope. Because explosive gases are not a problem in salt mines, the miners are carrying candles with naked flames for light. From Underground Life, or,

Stock Photo: 1746-1933 Polish miners at Wielleczka salt mine descending the shaft in a group of six each sitting in a loop of rope, with all six loops attached to a single rope. Because explosive gases are not a problem in salt mines, the miners are carrying candles with naked flames for light. From Underground Life, or,