Industrial Energy from Water-Mills in the European Economy, Fifth to Eighteenth Centuries: the Limitations of Power
Munro, John (University of Toronto)
Department of Economics University of Toronto, Published Online (2002)
The water-mill, though known in the Roman Empire from the second century BCE, did not come to enjoy any widespread use until the 4th or 5th centuries CE, and then chiefly in the West, which was then experiencing not only a rapid decline in the supply of slaves, but also widespread depopulation, and thus a severe scarcity of labour. For the West — those regions that came to form Europe — the water-mill then became by far the predominant ‘prime mover’: i.e., an apparatus that converts natural energy into mechanical power. The classic study, as a monograph in technological and engineering history, is Terry S. Reynolds, Stronger than a Hundred Men: A History of the Vertical Water Wheel (Baltimore and London, 1983). Indeed he has calculated that even the early medieval watermills provided about 2 hp, enough to liberate from 30 to 60 persons from the wearisome task of grinding grain into flour, the mill’s virtually sole use during the first millennium. He, and others, have neglected to note, however, that, apart from providing such economies in labour, water-mills also conserved on the capital and land resources (fodder crops) that would have been required to produce a comparable amount of power with animal-powered mills (horses, mules).