One of the first applications of spatial analysis in epidemiology is the 1832 Rapport sur la marche et les effets du choléradans Paris et le département de la Seine. The French geographer Charles Picquet represented the 48 districts of the city of Paris by halftone colour gradient according to the percentage of deaths by cholera per 1,000 inhabitants.
CGIS was an improvement over computer mappingapplications as it provided capabilities for overlay, measurement, and digitizing/scanning. It supported a national coordinate system that spanned the continent, coded lines as arcs having a true embedded topology and it stored the attribute and locational information in separate files. As a result of this, Tomlinson has become known as the father of GIS, particularly for his use of overlays in promoting the spatial analysis of convergent geographic data.