Essay

A 'Ghost Map': John Snow and the Mapping of Disease

In 2010 the UN General Assembly declared the access to clean water and sanitation a basic human right: such a statement may be surprising. However the lack of these fundamental infrastructures is among the causes of the pandemic of cholera that still affects millions of people worldwide. Like most epidemic diseases, cholera exposes the impact of environmental and health issues on geopolitics as it impinges on socio-economic situations and national and international security. (Price-Smith, 2009, 2; George, 2011, 147–154) It betrays a figurative alignment of anxieties about infection and concerns for political instability related to poverty, overpopulation, poor living conditions and economic and social inequality that renders disease a cultural construct as well as the product of pathogens.

This alignment was already evident in nineteenth century England, when cholera swept across Europe and North America causing thousands of deaths. It was a new infectious disease in Europe that had originated in the Indian Subcontinent and reached the west through commercial routes in the 1830s. (George, 2011, 134–143) The disease was felt like an invasion, 'Asiatic cholera took shape in the Victorian imagination as an Oriental raider, a barbaric force whose progress westward exposed the weak spots of an expanding industrial culture'. (O'Connor, 2000, 22) Inverting the trajectory of colonisation, cholera reproduced it in the form of an infectious epidemic, the more insidious and sinister because of its foreignness. The unpredictable patterns of its spread that mirrored the fluid circulation of goods and people typical of industrialisation and urbanisation were used 'as a metonymy for the disruptive effects of social change'. (O'Connor, 2000, 26) Its sudden and devastating symptoms, including dehydration, diarrhea and cyanotic skin, bore uncomfortable similarities with fears towards the filth and unsanitary conditions of the city, its contaminated sewers, and its crowded streets and houses that were thought to resemble the darkest corners of the Empire. 'Cholera thus became the operative term in an entire metaphorics of bodily contamination, a figure for the fluidity of boundaries in metropolitan space'. (O'Connor, 2000, 41) While the metaphors of cholera have intriguingly shifted from conservative Victorian rhetoric to post-colonial discourse, (O'Connor, 2000, 55–59) the fluidity of spatial urban boundaries has been absorbed into the systematising visualisation of the map and the concept of mapping as an alternative metaphor of control – if the map could not stop the spread of cholera, it could at least rationally contain it.

The miasmatic theory of contagion, still predominant in the 1850s, figuratively embodied the uncertainty, instability and randomness of cholera and urban life. Germ theory provided an analogy that endorsed the identification and fight against social and moral defiling caused by supposedly 'degenerative matter' – that of contagious pathogens and of social and racial mixing that resulted from growing urbanisation and colonial expansion. Indeed modern science attempted to frame the chaos and anxieties which cholera stood for, imputing it to an invisible though arguably traceable cause.

In this context, John Snow was not the first to use mapping to chart the spreading of the epidemic. He was the first to turn it into a means of visualising germ theory by linking the disease to contaminated water, as proved by mortality data and anecdotal knowledge collected with the help of Henry Whitehead. This led to the identification of the epicentre of the Broad Street outbreak at the water pump near the corner of Broad and Cambridge (now Broadwick and Lexington streets). (Stevenson, 2006, 192–196) In his 1854–55 map Snow added to the black bars, which indicated cholera deaths, a Voronoi diagram that delineated the area that was at closer walking distance to the Broad Street pump than to any other. The shape of contagion acquired new evidential clarity: 'Snow's visual case for his waterborne theory revolved around a striking correspondence between two shapes: the shape of the outbreak area itself, and the shape of best proximity to the Broad Street pump'. (Johnson, 2006, 196) The translation of walking distance and of the other locally gathered data onto the spatial grid of the map recalls the beginnings of cartography as the direct product of land surveillance, whereby cartographers established the visual paradigm of the linear two-dimensional reconfiguration of the relations between place and people through mathematical abstraction.

Snow appropriated the functionality of the map and 'peopled' it by adding new layers of information, thus redefining its purpose and inscribing within the layout of Soho's streets a knowable image of the spread of cholera based on its victims' habits. The uncertainty of the disease could thus be traced through foreseeable patterns that made detectable the polluting trajectory of the invisible pathogen within the urban fabric of 1850s London. The social and cultural anxieties that cholera epitomised still haunted Snow's map. Yet, he created a means through which the alignment of contagion, social and political fears could be addressed by rendering the spread of the disease observable and measurable. It is this possibility that still resonates today, distinguishing our concerns for epidemic infections from Victorian fears.

–Caterina Albano Artakt, CSM

References
Price-Smith, AT (2009) Contagion and Chaos: Disease, Ecology, and National Security in the Era of Globalization (Cambridge Mass., and London: The MIT Press)
Albano C (2012) Fear and Art in the Contemporary World (London: Reaktion)
George, R (2011) 'The Blue Girl: Dirt in the City', in Rosie Cox et al ed. Dirt: The Filthy Reality of Everyday Life, exhibition catalogue (London: Profile Books and Wellcome Collection, 2011), 134–162.
Gilbert, PK (c2008) Cholera Nation: Doctoring the Social Body in Victorian England (Albany: State University of New York Press)
Johnson, S (2006) The Ghost Map: A Street, an Epidemic and the Two Men Who Battled to Save Victorian London (London: Allen Lane)
O'Connor E (2000) Raw Material: Producing Pathology in Victorian Culture (Durham and London: Duke University Press)