Reconstructing the hydraulics of the world’s first industrial complex, the second century CE Barbegal watermills, France

Abstract

The Barbegal watermill complex, a unique cluster of 16 waterwheels in southern France, was the first known attempt in Europe to set up an industrial-scale complex of machines during the culmination of Roman Civilization in the second century CE. Little is known about the state of technological advance in this period, especially in hydraulics and the contemporary diffusion of knowledge. Since the upper part of the Barbegal mill complex has been destroyed and no traces of the wooden machinery survived, the mode of operation of these mills has long remained elusive. Carbonate incrustations that formed on the woodwork of the mills were used to reconstruct its structure and function, revealing a sophisticated hydraulic setup unique in the history of water mills. The lower mills used an elbow shaped flume to bring water onto overshot millwheels. This flume was specially adapted to the small water basins and serial arrangement of the mills on the slope. Carbonate deposits from ancient water systems are therefore a powerful tool in archaeological reconstructions and provide tantalizing insights into the skills of Roman engineers during a period of history that is the direct predecessor of our modern civilization.

Writ in water—Unwritten histories obtained from carbonate deposits in ancient water systems

“…The geometry of carbonate incrustations in water structures can give detailed information on their function. This has been applied to the function of inverted siphons and other water pipes (Kessener, 2001(Kessener, , 2016(Kessener, , 2022; of sluice gates (Kessener, 1995(Kessener, , 2000a and of special water gutters of watermills (Passchier et al, 2020;. 9…”