|Date||5 February 2012|
|Location||Dinorwic Quarry, Llanberis||SH 58782 60224; 53.12042°N, 4.11167°W|
Slate was commercially quarried at Dinorwic from 1787 until 1969. When the quarry closed, its workshops at Gilfach Ddu were acquired by the National Museum of Wales and are now home to the National Slate Museum, which first opened to the public in 1972.
The quarry was a hazardous place to work, as evidenced by the 362 fatalities recorded between 1822 and 1969. The hospital, located just above Llyn Padarn, was purpose built in 1860 so that those suffering injuries from accidents in the quarry could be quickly treated. The quarrymen and members of their families who fell ill received free treatment in the hospital. This was funded by the deduction of a shilling from the workers’ pay together with proceeds raised at charitable events.
With a diameter of 15.4 m, Gilfach Ddu’s 140-bucket waterwheel is the largest in mainland Britain (the Laxey Wheel on the Isle of Man has a diameter of 22.1 m). It was built by De Winton of Caernarfon in 1870 and was in service — powering all the workshops via line shafting running throughout the works — until 1925 when it was superseded by a much smaller but more efficient Pelton-wheel turbine. The waterwheel was restored in 2000 with support from the Heritage Lottery Fund and is in continuous operation. It is supplied with water via cast-iron pipes from an intake at Ceunant waterfall on the Afon Arddu above Llanberis.