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. Melin-y-Milwyr The tank at the head of the small road from Pumsaint to Caio was thought to be modern since it still holds water. However, when the level of the water was low in 1970, it yielded large quantities of Roman pottery which show that it is of Roman origin and built early during their exploitation of the mines. The section shows that it was connected to a smaller tank just below the modern road by a drystone culvert in a cascade. The lower tank also holds water but is in an advanced state of eutrophication. The collection of fragments included Samian ware and coarse ware from over 100 separate pots, and must have fallen into the reservoir when the mines were in full operation. Analysis of the pottery fragments showed a distribution of ages from the late 1st century AD through to the end of the 4th century. Since the fort and fortlet under the present village of Pumsaint ends in the middle of the 2nd century, it shows that mining continued for a long time after the military evacuation. It implies that there is a large mining settlement in the vicinity of the village of Pumsaint which has yet to be found. The exact function of the cascade is related to the methods of extracting the final traces of gold from the crushed ore. There were probably washing tables between the two tanks so that a gentle stream of water could be used to wash the ore