From Sketches to Publication: The Genesis of the Essai D'une Carte Géologique by Omalius D'halloy and Coquebert de Montbret (1810-1823)

While the Essai d'une carte géologique published in 1822 did not achieve the fame that its authors had hoped for, its history nevertheless deserves a closer look. Although its scale (about 1:3,700,000), and the technique used for making it (the map was coloured by hand at a time when the first geological maps printed in colour were appearing) make it a map of the past, it nevertheless testifies to the experiments and even cartographic tinkerings that were conceived in the 1810s by conciliating the expectations of the administration and those of science. Moreover, it offers a good example of the conditions of map production at that time. Without suggesting that the appearance of that Essai constituted a critical step in the history of cartography, this article examines the different steps that led to its publication, by considering first the investigative methods, then the different stages of map construction, and finally the uncertainties surrounding its publication, in order to grasp the stakes of such an enterprise, at the moment when reflections on the making of a geological map of France were developing, in particular at the École des mines.