  Duhem assumed the position of Maitre de Conférences at the Faculté des Sciences at Lille in October 1887. There he met Adèle Chayet, whom he married in October 1890. Their daughter Hélène was born in September 1891. Tragically, Adèle died in childbirth the following summer; the newborn child also did not survive. Duhem never remarried. He left the upbringing of Hélène to his mother who lived with him after his father Pierre-Joseph died. The situation in Lille soured for Duhem. Never one to back off from a dispute, he fought with the Dean of his faculty over a minor issue: an assistant had failed to unlock the door of Duhem’s laboratory for his students during their licentiate examinations. The assistant complained about his mistreatment by Duhem to the Dean, who requested that the assistant write a letter of apology; Duhem rejected the apology and took issue with the Dean, who then brought the matter to the Rector, adding further complaints against Duhem. The minor issue having escalated to immense proportions, Duhem requested and received a change of positions at the end of academic year 1893. During these formative years, Duhem worked very hard on his science. He published six books: a two-volume work on hydrodynamics, elasticity, and acoustics, his lectures on electricity and magnetism, in three volumes, and an introduction to physical chemistry. Duhem was one of the first to appreciate the work of W. J.  Gibbs, writing the earliest critical examination of Gibbs’ “On the Equilibrium of Heterogeneous Substances” in 1887 and later promoting the French translation of Gibbs’ works (Duhem 1907); for an English translation of Duhem’s 1887 essay on Gibbs and his Commentaries on the Principles of Thermodynamics, 1892–1894, see Duhem [CPT].