Coloured aquatint engraving by J Bluck after an original work by R H Marten, showing the underground chamber of a Cheshire salt mine. The earliest known Cheshire salt mine, sunk in 1682, was flooded in 1720. The ease of mining compared with the difficulty of draining flooded mines meant that new pits were sunk in preference to pumping water from old ones. By the second half of the 19th century there were many salt-producing busineses in Cheshire.
© Science Museum / Science & Society Picture Library