The Rise of a Utilitarian Concern in Seventeenth-Century Moon-Mapping: The Case of Giovanni Domenico Cassini’s Grande Carte de la Lune (1679)

After Galileo’s remarkable demonstration of the rugged surface of the moon, several attempts to provide a comprehensive cartography were conducted, culminating with Johannes Hevelius’s lavish Selenographia (1647). By representing each phase of the moon, Hevelius did not only intend to give an accurate description of the satellite, but also to provide a detailed physical explanation of its behaviour. Such a clear purpose contrasts with the Grande Carte de la Lune completed thirty years later in the Royal Academy of Sciences. The project, directed by Giovanni Domenico Cassini, began in the early 1670s, soon after the construction of the Observatory. Once achieved, the map was deemed the most precise ever done, and yet its purpose and application have hitherto remained mysterious. While the print was directly financed by the Surintendance des Bâtiments du Roy, the few scarce copies retained in public collections lack any dedication or legend, suggesting that the project was not deemed as desirable as it may have been at the beginning. Indeed, a few years later, Cassini felt compelled to justify the usefulness of moon-mapping. Through the careful analysis of the fabrication and reception of the Grande Carte de la Lune, I hope to detail the shift from a conception of science closely associated to courtly practices to a more utilitarian view. I will then attempt to discuss how such a shift was partly determined by the economic policy of the Bâtiments du Roy, but also by internal conflicts within the Academy.