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Latitude: 53.0542 / 53°3'15"N
Longitude: -4.2435 / 4°14'36"W
OS Eastings: 249732
OS Northings: 353122
OS Grid: SH497531
Mapcode National: GBR 5K.CMMX
Mapcode Global: WH43T.SHHG
Entry Name: Engine House, Boilerhouse, Bunker and remains of chimney to south
Listing Date: 10 December 1992
Last Amended: 21 July 2000
Source ID: 22901
Building Class: Industrial
Location: On a ridge of bastard rock which divides the main Dorothea Quarry from the South Dorothea Quarry; located by the side of the road access to the quarry.
Built-Up Area: Talysarn
Traditional County: Caernarfonshire
The Dorothea Quarry in the centre of the Nantlle vale was opened in 1829 by William Turner and John Morgan. From 1853 the quarry was owned by the Williams family until its closure in 1970. In 1904 (date on foundation stone) a Cornish beam engine was installed, replacing water power, to provide power for lifting wagons in and out of the open pits and to pump out the workings through a shaft about 140m deep. The engine, manufactured by Holman Bros. of Camborne (Cornwall) remained in regular use until 1952 and occasionally until 1956.
Sawn squared slate blocks with gable-ended slate roof 3 storeys over basement. Rectangular plan, aligned roughly north-west to south-east. Small-paned sash windows with slate lintels and cills on each face. Entrance in south-east end wall under brick arch approached by sawn slab steps. Large ground-floor opening in north-west end wall, also with brick arch. Remains of clock high up between top-floor windows on north-east wall. Iron beam of engine supported high up on north-west wall and projecting through vertical timber boarding in gable; pair of doors flanking beam open out on to remains of wooded inspection balconies. At the north-west end the shaft head is surrounded by a wall of sawn slate blocks approximately 2m high and attached to the engine house; the shaft head is spanned by 2 steel joists. Against the south-west wall of the engine house are the remains of the boiler house, now roofless but with the principal timbers surviving; it houses the remains of 2 boilers. To the south is the square base of the remote chimney, constructed of sawn slate blocks, approximately 3m high; the former iron extension has been removed.
Access to interior not available at time of survey but noted as retaining its early C20 Cornish beam engine.
Listed Grade II* as the only remaining example of an engine house with a Cornish beam engine remaining in situ within the area of the Gwynedd slate industry.
Scheduled Ancient Monument (No.165).
Other nearby listed buildings