The rubble near to the camera is spoil from an old mine level. In the centre of the image the ruined building is actually an old wheel pit; beyond the pit there's a shallow, partly stone-lined groove which ends at a water-filled shaft. Disappearing into the shaft is a section of chain in the style of a very heavy duty bicycle chain. It's assumed that the rotation of the wheel in the wheel pit operated rods along the groove to give a 'horizontal' reciprocation. The chain then converted that motion into a vertical reciprocating action which would operate a pump to drain water from mine workings below.
Uploaded to Geograph by Trevor Littlewood on 14 July 2011