Lake Vyrnwy, North Wales, 1889.
© Science Museum / Science & Society Picture Library
Plate taken from the 'Illustrated London News'. The huge masonry dam spans the river valley. Completed in 1889, it was the first large stone-built dam in Britain. Earlier dams had just been created by making earth embankments. Lake Vyrnwy was needed to provide a storage reservoir of safe water for the rapidly growing city of Liverpool. The factories too needed large quantities of water for their steam-driven machines.