Économique et mécanique

[Note on Electronic Edition: This is an electronic version of Léon Walras's article "Économique et Mécanique" (1909, Bul. Soc. Vaud. Sc. Nat.). The appended 1901 letter from Henri Poincaré was included in Walras's original article. We draw from the version reprinted in 1960, Metroeconomica, Vol. 12, No. 1 (April), p.3-13 (ed. G.H. Bousquet). Page numbers in bold square brackets, e.g. [p.5] denote the beginning of the respective page in the 1960 Metroeconomica version. Page numbering is also noted for the footnotes. Otherwise, the text (including errors) is unchanged.