1-158-487 - Oxford Science Archive/Heritage Images

Pound lock, 1664. The vessel has entered the pound from the lower level on the left, the gate has been closed behind it and water is being allowed to flow through the gate on the right, gradually raising the water level so that the boat can float out. Pound locks are used on canals, or to transfer vessels from one waterway to another at a different level. From Nouvelle Invention de Lever l'eau Plus Hault (New Invention for Raising Water ...) by Isaac de Caus. ( London, 1664).