G.O. Brown - Henry Darcy and the making of a law (796978)
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WATER RESOURCES RESEARCH, VOL. 38, NO. 7, 1106, 10.1029/2001WR000727, 2002Henry Darcy and the making of a lawG. O. BrownDepartment of Biosystems and Agricultural Engineering, Oklahoma State University, Stillwater, Oklahoma, USAReceived 19 June 2001; revised 28 November 2001; accepted 13 February 2002; published 17 July 2002.[1] Henry Darcy was a distinguished engineer, scientist, and citizen who is rememberedfor his many contributions in hydraulics, including Darcy’s law for flow in porousmedia.
While he has been given full credit for the finding, little insight has beenavailable on the process of his discovery. It is shown that his discovery was the logicalresult of a lifetime of education, professional practice, and research. Darcy understoodboth its significance and its relationship to the broader fields of hydraulics andgroundwater hydrology. Besides the discovery of Darcy’s law, he was the first to showthat significant flow resistance occurs within aquifers, the first to recognize the law’ssimilarity to Poiseuille flow, and the first to combine the law with continuity to obtain aINDEX TERMS: 1719 History of Geophysics: Hydrology; 1829solution for unsteady flow.Hydrology: Groundwater hydrology; 5114 Physical Properties of Rocks: Permeability and porosity;KEYWORDS: Darcy’s law, Corps of Ponts et Chaussées, Dijon, France1.
Introduction[2] In 1856, Henry Philibert Gaspard Darcy (1803 –1858), in a report on the construction of the Dijon, France,municipal water system, published a relationship for theflow rate of water in sand filters [Darcy, 1856]. In termsonly slightly different from his own, Darcy’s law was givenasQ ¼ AKðh1 þ z1 Þ ðh2 þ z2 Þ;Lð1Þwhere Q is the volume flow rate, A is the area of porousmedia normal to the flow, K is the hydraulic conductivity, his the pressure head (pressure divided by the specificweight), z is the elevation, L is the length of the flow path,and the subscripts 1 and 2, designate the up and downstreampositions, respectively.
The term within the parentheses isthe hydraulic or piezometric head. A photo of Darcy takenlate in his life is shown in Figure 1.[3] Equation (1) has of course been generalized by manywriters to allow for differential solutions, vector analysis,unsaturated flow and multiphase flow. Likewise, the equation’s theoretical basis and applicability in several fields hasbeen well defined.
Conversely, little has been published onthe process of the discovery. This deficiency may beexplained in part by the facts that Darcy lived 150 yearsago, copies of his writings are difficult to obtain, and littlehas been translated from the French. Even native Frenchspeakers have difficulty interpreting terminology inconsistent with modern usage wrapped in old flowery prose.However as will be shown, Darcy was a person of unusualability who had worked in the field for decades. Hisdiscovery was the logical conclusion of a lifetime ofeducation, professional practice and research.[4] Several writers have previously addressed Darcy’slife.
Marsaines [1858] and Caudemberg [1858] publishedCopyright 2002 by the American Geophysical Union.0043-1397/02/2001WR000727$09.00detailed obituaries based on firsthand accounts. Both areexcellent documents, but each suffers from a lack ofhistorical perspective. Tarbé de St-Hardouin [1884] andFancher [1956] based their short biographies on Marsaines’ account, while in turn most recent publicationsare based on them. Hubbert [1969] reviewed Darcy’sexperiment, while Rao [1968] summarized Darcy’s majorcontributions to hydraulics.
R. Freeze in the work ofFreeze and Back [1983] performed a partial translationof Darcy [1856] as part of an excellent collection of earlygroundwater papers. An interesting nontechnical perspective on Darcy’s times was presented by Freeze [1994] thatincorporated new material translated from Darcy [1957].P. Darcy was a great nephew of Henry’s and may be theColonel Darcy referred to by Fancher. The biography doesnot appear on any book list and was found by Freeze in aDijon bookstore.
P. Darcy’s work contains a considerableamount of interesting personal and historical information,but the author was obviously not technically trained.Philip [1995], using archival material from the DijonBibliothéque Municipale, rebuked Dijon for forgettingher native son. Of final note, Brown et al. [2000] havepresented a brief summary of his work and reexamined thespelling of his name.[5] Using a limited number of source documents, previous writers have clearly shown that Darcy was a greatengineer and citizen, but they have shed little light on theprocess of his discovery.
However, by examining theFrench, English and American technical publications ofthe day, we can discern what Darcy knew, when he knewit and how his work related to the developing sciences. Anexhaustive search was made to find any publication byDarcy, and all identified were reviewed and referenced here.Likewise, all cataloged Darcy biographies were examinedand any that contain original material have been cited. Otherauthors, in particular Rouse and Ince [1957], have beenused to identify the other relevant publications of the nineteenth century. Original source material was given highestvalue, but current theoretical insight is also applied to infermissing information when necessary.
While the story is11 - 111 - 2BROWN: HENRY DARCY AND THE MAKING OF A LAWemphasized math, science, engineering and hands-on laboratories. The latter was considered innovative at the time.All students took military studies, and the school was theprimary source of the officers for Napoleon’s very effectiveartillery corps. Gaspard-Marie Riche de Prony (1755 – 1839)had been the school’s primary guiding intellect since 1800,and the Polytechnique had taken a central role in all areas ofFrench science and engineering education by the time Darcyenrolled. Likewise, its student body usually played a partduring periods of civil unrest and had manned the streetbarricades more than once.[8] Darcy’s short student record from the Polytechniqueprovides a glimpse of him at this time (C.
Billoux, ÉcolePolytechnique Bibliothéque, Paris, Responsable du servicedes archives, letter dated 24 October to G. Brown, 2000.)He was 1.69 m tall (50 – 61/200), had light brown hair withbangs, blue eyes and a cleft chin. Within the student corps,he obtained the level of Sergeant Major. That and his classrank of 12 out of 64 at the Polytechnique, and 8 out of 15who proceeded to the Ecole des Ponts et Chaussées indicates he was a good, but not the best student.3. Ponts et ChausséesFigure 1.
Portrait of Henry Darcy by F. Perrodin, from theCollection of the Bibliothéque Municipale de Dijon.incomplete, enough of the plot can be deduced to outline thepath that was followed. Sometimes the text is vague, but theequations and data leave little to debate.2. Formative Years[6] Darcy was born 10 June 1803 in Dijon, France. Hisfather, Jacques Lazare Gaspard was a tax collector, and hismother was Agathe Angelique Serdet [Darcy, 1957].Located southeast of Paris, Dijon is the former capital ofthe Duchy of Burgundy. It has a long notable history andmany beautiful historic buildings.
It was, and remains, thecenter of the great Burgundy wine region, and is capital ofthe Department of Côte d’Or. However, at the start of thenineteenth century it was a provincial backwater and had apopulation of less than 30,000. At the national level, thebrutality of the French Revolution was over and France wasentering a period of relative prosperity fueled by theindustrial revolution. While the country could hardly bedescribed as being stable as it proceeded through a series ofgovernments, rulers and revolts, education was supportedand the bourgeoisie grew in size and influence.[7] Darcy’s father died when he was 14, but his motherassured his education by borrowing money for tutors and byobtaining a city scholarship for him to attend college. In1821, Darcy entered L’Ecole Polytechnique, Paris.
ThePolytechnique was created during the French Revolutionin 1794 with the mission to replace several small Royalschools with a comprehensive three-year program in allbranches of engineering [Bradley, 1998]. The curriculum3.1. L’Ecole[9] In 1823, Darcy was admitted to L’Ecole des Ponts etChaussées (School of Bridges and Roads), Paris. The stepfrom the Polytechnique to an ‘‘Ecole d’application’’ was thenormal progression for the better students at the time, and itwould shape the course of the rest of his life.
Firstassembled in 1716, the Corps of Ponts et Chaussées hada mission to support infrastructure construction throughoutthe country. By decree of the Royal Council in 1747, theSchool was created to train both new students and practicing engineers for the Corps. As the first modern engineeringschool, it elevated engineers in France to the status of aprofession. Together, the School and the Corps provided anenvironment that both expected excellence and furnishedthe support to achieve it. A list of the school’s graduatesand instructors reads like a who’s-who of eighteenth andnineteenth century engineering and science.
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