I have always admired Henry Darcy, but never thought to join his fan club—you can at this link. There you can find all the intimate details of his birth, life, and death. There is even some information on his works and equation. Here is some background history on Darcy:

Darcy was a French Civil Engineer from École des Ponts et Chaussées. He developed his theory (1856) while working for the water supply of the City of Dijon. At Darcy’s time, hydrogeology was still arguing about the Greek water cycle, from the sea to the continents. Father Paramelle’s famous book “The art of discovering springs” (1856, 1859), with no mention of Darcy’s work, was the best seller, not Darcy’s. Fourier (1768-1830), a French Professor and Academician, taught Darcy his law. Poiseuille’s (1844) and Ohm’s (1827) laws were also familiar to him. Politically, Darcy was born during a troubled period of France’s history, starting with the Revolution (1789), then Napoleon Bonaparte’s Consulat, Empire, the restored French Monarchy, the failed revolution of 1830, the 2nd Republic, and the 2nd Empire. He was a graduate from an engineering school, organized by Napoleon to support the empire’s wars, but also its economic development: roads, bridges, water supply…

From Water Resources Research for $9 you can buy a paper with this abstract, which is informative but not so amazing that it induces me to part with money.

Henry Darcy was a distinguished engineer, scientist, and citizen who is remembered for his many contributions in hydraulics, including Darcy's law for flow in porous media. While he has been given full credit for the finding, little insight has been available on the process of his discovery. It is shown that his discovery was the logical result of a lifetime of education, professional practice, and research. Darcy understood both its significance and its relationship to the broader fields of hydraulics and groundwater hydrology. Besides the discovery of Darcy's law, he was the first to show that significant flow resistance occurs within aquifers, the first to recognize the law's similarity to Poiseuille flow, and the first to combine the law with continuity to obtain a solution for unsteady flow.

The formulation of the law that best approximates the way it was introduced to me is this

Q=KA (h1 − h2) / L


where:

  • Q is the flow rate
  • K is a permeability coefficient (describes the porosity of the underground formation),
  • A is the cross sectional area,
  • h1 is the height of the inlet head,
  • h2 is the height of the outlet head, and
  • L is the path length of the flow.

For the practical engineer is this link where you can solve the equation in its many forms by plugging in parameters.

The most fascinating paper on Darcy approaches his theory form the point of view of a philosophy—you have to read it to believe it. An even stranger site includes an attack on Darcy’s law and the claim that it is fundamentally incorrect. And on that note, what more can be said?