Roman Water-Power
This chapter summarizes the archaeological evidence currently known for Roman water-mills, tracing the development and spread of water-powered grain milling over time across the Roman Empire. Problems of quantification and evidence bias, both documentary and archaeological, are addressed. In particular, it is argued that large discoidal millstones, formerly thought to derive either from animal-powered or water-powered mills, must come from water-mills, and that the idea of Roman animal-driven mills with discoidal millstones is a myth. This dramatically increases the amount of evidence available for water-powered grain milling, although very unevenly spread across the empire, and heavily dependent on the intensity of research in particular regions—good for Britain, parts of France, and Switzerland; poor everywhere else. The chapter also summarizes the state of knowledge on other applications of water-power—for ore-crushing machines at hard-rock gold and silver mines (by the first century AD), trip-hammers, tanning and fulling mills, and marble sawing (by the third century AD). The picture is fast-changing and the body of evidence continues to grow with new archaeological discoveries. The chapter ends with some thoughts about the place of water-power in the overall economy of the Roman world, and on the transmission of water-powered technologies between the Roman and medieval periods.