It was a popular machine for pumping water of large differences in height that was used until recently. It consisted of two closed parallel chains wrapped around a triangular upper construction and often a lower identical construction that sometimes-had wings for its water- driven motion. The chains incorporated wooden or metal vessels that had an opening at their upper part for the inflow of the abstractable water when they were at the lower point in their course and for the outflow of water when they were trapped at the higher point. The energy required for the movement of the wheel came from the built-in water- driven wings of the lower triangular construction or from a cooperating foot-powered wheel.

SOURCES: Philon of Byzantium, Pneumatics, 61, Vitruvius, On architecture, X 4.