Henry Philibert Gaspard Darcy (1803-1858), a French scientist who made many important contributions to hydraulics. Darcy invented the modern style Pitot tube, a device for measuring the velocity of water. He stated Darcy’s Law (1856), a mathematical relationship that governs the flow of groundwater through granular media or the flow of other fluids through permeable material, such as petroleum through sandstone or limestone. As a leader of the Corps of Bridges and Roads in France, he built an impressive pressurized water distribution system in Dijon, France that carried fresh water from Rosoir Spring, 12.7 km away, through a covered aqueduct to reservoirs near the city, which then fed into a network of 28,000 meters of pressurized pipes delivering water to much of the city. The system was fully closed and pressurized by gravity, and thus required no filters or pumps.