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Cof Cymru: National Historic Assets of Wales · Wales

Engine House, Boilerhouse, Bunker and remains of chimney to south

Llanllyfni, Gwynedd, Wales

The record

Designation
Listed building, Grade II*
Broad class
Industrial
Date of designation
10 December 1992
Locality
Nantlle
Community
Llanllyfni
Unitary authority
Gwynedd
Country
Wales
Coordinates
53.05417, -4.24347
Cadw reference
22901

Slide toward Today to fade the historical sheet and see the modern map underneath.

David Rumsey Map Collection, Stanford Libraries

Shown on 5 historical map sheets, the earliest the 1795 "To Sir Watkin Williams-Wynn Bart ... the map of the six counties of North Wales is most humbly inscribed by his obedient humble servant" (Llyfrgell Genedlaethol Cymru – The National Library of Wales).

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This record in Cadw's own full report ↗

Cadw's description

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.

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).

Nearby in the register

Other entries of the same register within about three miles of this one, by straight line.

Designated Historic Asset GIS Data, The Welsh Historic Environment Service (Cadw), 2026-09-07, licensed under the Open Government Licence http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ Cadw, the Welsh Historic Environment Service · Open Government Licence v3.0
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