Between scientific rigor and perceptive component. Representing the landscape of the “royal salt works” of Cagliari in the 19th century (Sardinia, Italy)

The case study is part of a research that analyzes the potentiality of historical maps as a tool to support the knowledge and protection of the landscape. The main interest of this article is to highlight data qualities and communicative capacities of 19th century cartography of Sardinia also in relation to the current state of the art. The drawing of landscape and territory at this time shows an interesting ability to combine scientific rigor and perceptive component that will have its maximum expression in 1845 with the work of the general Alberto Ferrero Della Marmora. Starting from a critical analysis of the archive documents, the methodology adopted in this case study needs the drawing/design of a geo-referenced database aimed at a comparison between historical maps and the series of aerial surveys made available by Cartography Service of the Sardinia Region. The subject of this analysis are some interesting drawings that describe the system of “Royal salt works” of Cagliari designed by Piedmontese government in the first half of the nineteenth century, surveyed and represented by military officers. The territorial data recorded in the examined maps shows an interesting compatibility with the most recent acquisitions and allows a diachronic analysis of the transformations. To this end – putting together the high precision of current survey and representation methods with information and immediacy of historical cartographic production - the drawings are analyzed, elaborated and “communicated” through graphics models able to express by signs the complexity of a stratified landscape.