Engine House and Attached Boiler House at Sw594290 Wheal Grey

The building comprises a disused engine house and attached boiler house, dating to circa 1897. It is constructed of granite rubble with dressed granite quoins and jambstones, featuring brick arches. The engine house is rectangular, with a bob wall and shaft facing north. An attached lean-to boiler house extends eastwards and continues southwards. A wall runs parallel to the boiler house, positioned in front of the south wall of the engine house. To the south of this wall stands a small square building, connected to the north end of the boiler house by a screen wall. A pair of buttressed, parallel whim-bearing walls stand at right angles to the shaft. Within the boiler house are two long, masonry-lined trenches, and the building south of the engine house contains several bearing walls with iron bolts, remnants of former machinery. Two bearing walls are positioned in front of the main doorway. The original machinery, floors, and roofs have been removed. The building rises three storeys over a basement pit. Round-headed openings are present throughout. The engine house has an opening to each floor of the south gable, and two openings in the bob wall, now reduced to one due to fallen masonry. Ground floor openings are located in the side walls, with a doorway and a smaller opening above and to the left on the east wall, alongside a complete cross beam in situ. The boiler house features a round arched opening at the south end and a doorway with a window above at the north end; a doorway is blocked in the west wall. The engine house was originally built for a 36-inch cylinder beam pumping engine, which had been converted from a rotative engine. Initially constructed by the Charlestown Foundry for Polgooth mine in the 1840s, it was later used as a stamps engine and finally scrapped in 1935. The engine house and its associated structures represent one of the most complete examples in Cornwall, with particularly interesting surviving bearing walls reflecting a complex arrangement of whim and other machinery.