Llanberis, Gwynedd

With a diameter of 15.4 metres, the waterwheel at the National Slate Museum, Llanberis, is the largest in Britain. Used between 1870 and 1925, this powered all the machinery in the workshops via an ingenious system of pulleys and pinions which ran throughout the building. It is fed by water taken into a cast iron pipe at Ceunant waterfall in the mountains above. In 1925 it was superceded by the Pelton Wheel, a more reliable, and more compact design which used the kinetic energy of water at high pressure, and which was housed beneath the old wheel. The water wheel was restored in 2000, and now works continuously.

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