The existing ponds above and below the minor road from Pumsaint to Caeo, were probably part of a cascade for washing ore, the upper tank having yielded large quantities of Roman pottery from to at least 300 (Lewis, 1977; Burnham 2004). The upper pool is known as Melin-y-Milwyr, or the soldiers' mill, an intriguing name that implies that watermills may have been used here during the Roman period. Alternatively, it may have been a sequence of washing tables for the crushed gold ore. A large-scale mill complex is known from Barbegal in southern France, where no less than 16 mills (in two lines of 8 each) were built into the side of a hill and supplied with water from a single aqueduct. There were two lines of parallel overshot mills, the outflow from one feeding the next below. The mill supplied flour to the region. Moreover, Roman engineers used sequences of reverse overshot water-wheels to dewater mines, and the deep workings at Dolaucothi produced a fragment of such a wheel during the 1930s when deep mining operations were resumed. Sequences of such wheels increased the lift, and one extensive sequence of 16 wheels was found in old Roman mine workings on the Rio Tinto river in the 1920s. The wheels were arranged in pairs and could lift water about from the bottom of the mine there.
