A French engineer who specialized in fluid hydraulics. In France, he was responsible for many significant hydraulic projects including the construction of a remarkable pressurized water network system in his birth town of Dijon. He developed a way of calculating head loss due to friction, which with further modification by the German mathematician and engineer Julius Weisbach (1806–71) became known as the Darcy–Weisbach equation. The unit of permeability, the darcy, is named after him.