22655

 

II  

Designated  

04/11/1999  

04/11/1999  

Slate Dressing Mill (Australia Mill)  

 

Gwynedd  

Llanddeiniolen  

Caernarfon  

Dinorwic Slate Quarry  

259995  

360334  

 

Spectacularly situated towards the top of the south-eastern (Braich) side of the former Dinorwic Slate Quarry.  

Industrial  

 

The Dinorwic Quarry was first established in 1787, taking over existing workings in the area, the first incline being built in 1789. By the 1830s there was a tramway system on each terrace of the quarry, steam locomotives being introduced in the 1870s. The eventual scale of the quarry was such that its output of c100,000 tons p.a. in the late 1890s put in on a par with Penrhyn, representing almost a quarter of the total production of Welsh slate. The quarry finally closed in 1969. The mill was built in the late C19 and was originally steam-powered, being converted to electricity after alternating current was introduced from Cwn Dyli power station in 1905. Despite being used right up to closure, the mill had no trimming machinery, all trimming continuing to be done by hand.  

Regularly coursed rubblestone and slate slab construction; gable-ended slate roof with slates stripped off at time of Survey. Very long rectangular plan with 2 gabled projections on north-eastern long wall; corresponding south-western side has full-length very shallow-pitched lean-to with pedestrian doorways at regular intervals, no windows. Main entrance carrying railway track is at north-western end with louvred window to apex of gable.  

Multi-trussed cast-iron tie beam and raking strut structure to main building with massive iron girders supporting 3-purlin roof structure in lean-to. Main building retains its 36 saw tables virtually intact carrying Ingersoll Rand plates apparently of Turner pattern with railway track running alongside. Regularly spaced open doorways in long south-western wall give access to lean-to with its slate slab bins.  

Included, notwithstanding loss of its slate roof covering, as a well-preserved slate dressing mill forming an integral part of the former Dinorwic Slate Quarry complex, particularly notable for the fact that despite being used right up to closure in 1969 it had no trimming machinery, the building therefore providing a remarkably good example of a C19 slate dressing mill.