Chain pumps
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Chain pumps are a kind of water pump where an endless chain has positioned on it a series of circular discs. One end of the chain dips in to the water, and the chain runs through a tube, slightly bigger than the diameter of the discs. As the chain is drawn up the tube, water becomes trapped between the discs and is discharged at the top.
This kind of pump was known in Roman times, sometimes with pots fixed to the chain, which, as they passed over the top pulley, tipped the water out. They were used in European mines in the Renaissance, and illustrated by Georg Agricola in his De re Metallica; they were used in dockyards, and number formed part of the Portsmouth Block Mills complex. Chain pumps were commonly used on naval vessels of the time to pump the bilges, and are examples are known in the nineteenth century for low-lift irrigation purposes.