Caer Eithin Engine House, Berthlwyd Colliery

A complex structure of local sandstone rubble with features in red brick. Its main part is a mass about 10m by 8m and about 5m high, through which a large brick-vaulted tunnel passes north-south, widening out on the north face. From within the large tunnel a small sloping tunnel extends downwards to the east. Two substantial additional wings of brick and stone extend to the south, between which there is an area of raised ground containing two small parallel blind tunnels in brickwork. There were additional buildings to south and east, now lost, and a top storey. The historical evidence indicates that at ground level there was a steam engine. It is probable that its steam raising equipment was located at the south side, perhaps on the raised platform. A small amount of coal would probably be drawn up from the mine to provide fuel for the boilers. On the south face of the surviving structure there are indications of an abutting roof, taken to be that of a boiler house. No chimney position is apparent. The top storey has been reinforced with steelwork to create a larger platform by cantilevering five rolled steel joists outwards on the east and west sides and forming a set of tied brick arches between them. The engine installed at the top is thought to have been electrically powered. Local oral evidence suggests there was a ladder on the west face giving access to this upper engine house. Another platform of steel joists with brick arches, at about 1m lower level, forms a roof between the south-pointing wing walls. On the east face of the eastern wing wall is the mark of another roof, indicating there was an abutting building on this side; a narrow opening gave pedestrian access between the suriving structure and this lost building.