Slate Mill

Cadw's description

Location

Directly adjoining the slab mill to the south on Level IV (Bonc Isa') of Pen-yr-Orsedd Slate Quarry.

History

Built adjoining the older slab mill in the late 1870s to house 27 De Winton hydraulic feed-saw tables and 26 dressers. At first it was powered by a wire rope transmission from the water-wheel and steam engine power sources in the Level VI mills but after 1906 electric motors were installed in its roof trusses. The slates were removed from the building's roofs c1997. The quarry opened c1816 when it was worked by William Turner. In 1863 it was bought by W A Darbishire & Co., after which it underwent substantial modernisation, reflected in the use of both water and steam power. During the 1890s about 450 men worked here; it finally closed in 1997.

Exterior

Vast rectangular plan slate-slab structure aligned roughly north-west to south-east comprising parallel gable-ended ranges with central valley; the roofs have been entirely stripped of their slates. Doorway roughly in centre of south-west long wall with red brick dressings, raking buttresses and concrete lintel; further entrance in far north-east corner.

Interior

King-post roof trusses throughout, the central roof valley supported on a combination of timber posts and slate-slab piers, the former predominating. The line shafting for the former De Winton hydraulic feed-saw tables survives.

Reason for designation

Included as a well-preserved integrated slate mill (notwithstanding loss of its roof covering), significant in illustrating an important advance in technology and the intensive factory approach to slate processing adopted at Pen-yr-Orsedd; part of the remarkably well-preserved complex of buildings on the site.