The Map as Intent: Variations on the Theme of John Snow

Critical geographers" concerned with cartography insist maps are first and foremost social artefacts that must be "read" as authorial documents rather than perceived as data statements. Their argument is typically dismissed as trivial because the relation between intent and output has rarely been demonstrated in a critical way. This article seeks to demonstrate the degree to which authorial intent defines map content and appearance through an analysis of a single set of maps. All are based on the original data collected in 1854 by Dr John Snow as part of his study of the cholera outbreak in London's Soho district. Snow's original map is included as baseline for a study that includes versions of the Snow map by a range of authors, including Cliff and Haggett; the US Centers for Disease Control; Gilbert; Tufte; and Monmonier. The resulting appropriations bear progressively less resemblance to the original work, despite the use of the same data set and its clear availability. The result is a cautionary tale of the distance between maps and the data they represent. The article also insists upon the close relation behveen authorial intent and mapped result irrespective of the data available. Finally, the article concludes that because mapping is not value-free, dangers occur when professional cartographers and geographers attempt to map data from fields in which they are ignorant.