Pump Engine House to Marriott's Shaft on South Wheal Frances Sett

The pump engine house for Marriott's shaft, located on the South Wheal Frances sett, is a late 19th-century structure built for the South Frances United Mine. It is constructed of granite rubble with quoins and features brick arches over its openings. Currently roofless, the building has a rectangular plan aligned on a north-south axis, with a pump opening at the south end and a chimney attached at the north-east corner. The building stands two stories high, with the gabled front wall showcasing a large round-headed opening that overlooks the former shaft, which is now capped with concrete. Above this opening, there is a circular window at the apex of the gable. The rear wall has a similar large round-headed opening, which was once a large window on the first floor, with the masonry beneath it removed, and a circular window above. The sides of the building feature round-headed windows on the first floor. The cylindrical chimney is slightly tapered and currently lacks its upper brick stage. The interior is not accessible.

Historically, this engine house was built to replace a former engine house that was destroyed by fire in 1895. It housed an inverted compound beam engine, noted to be the only one of its kind to operate in Cornwall, with the beam working beneath the floor and pivoting within the house itself, while the cylinders were mounted on the floor above, supported by massive interior buttresses. This site was part of one of the best-equipped mines in Cornwall, which closed in 1918. The pump engine house is recognized as a central element of a significant group of industrial heritage.