 Following Volta's visit to Paris in 1801 important work on the Voltaic pile, involving the Arcueil circle, was carried out under Bonaparte's auspices rewarding Paul Erman, Humphry Davy, Gay-Lussac and Louis Jacques Thenard in the process.The scientific work in general was of first importance to the education at the Ecole Polytechnique, the home base of many Arcueil scientists.The enhancing of the quality of iron and steel, with Collet-Descotils -the precursor in the discovery of iridium- in charge as chief engineer at the "Ecole des Mines", and above all the development of gunpowder were of prime military significance.