Engine House At Sw 600265, New Engine Shaft, Trewavas Mine

The Engine House at SW 600265, New Engine Shaft, Trewavas Mine, is a ruin of a beam engine house built around 1838 for a 45-inch pumping engine. It is constructed from granite rubble, featuring partly dressed granite quoins, jambstones, and lintels, as well as dressed granite voussoirs forming a round arch over a plug doorway. The building has a rectangular plan with a thicker bob wall on the southwest side, which includes a tall plug doorway at the pit floor level. The machinery, floors, studwork wall, gable over the bob wall, and roof structure have been removed. Originally, the structure had three floors above a basement pit at the front.

The engine house is dramatically positioned on a steep cliff, with the shaft located in front of the bob wall on the seaward side. The bob wall features a tall central round-headed plug doorway leading to the basement and ground floor. The rear wall has a doorway for the boiler on the ground floor and window openings on the first and second floors, although the gable over the upper opening has collapsed. Each side wing wall contains two widely spaced ground floor openings and a central first floor opening, with the first floor window on the right-hand wall blocked.

On the left side of the shaft, in front of the bob wall, there is a masonry slot for the former balance bob, likely added when the mine became too deep for the main beam to support the load alone. To the northwest, there is a capstan platform, and further up the cliff, a horse whim platform. Wheal Trewavas was a copper mine that operated from around 1834 to 1846. This engine house and its associated features are situated in a striking location about three-quarters of the way up a steep cliff and are part of a notably complete group of mining remains.