Tooling up for Complexity - Participatory Mapping: New Data, New Cartography - page 17

Street with a factory on the same street which did not show
any victims. As he went to investigate on site, Snow realized
that the workers from the factory were not using that
water pump as they only drank beer. This gave
additional backup to his theory on the contamination of
water [TUF 97, p.27-35].

Figure 1.3. Cholera epidemic in Soho, mapped by John Snow, 1954. The
black bars locate the number of dead 4

John Snow's map is a tool both for the analytical process
and the communication of the results. This case study
emphasizes the analytical properties of maps by showing a
geographically based causal relationship among different
datasets so as to prove or disprove a hypothesis. Maps are

4 Taken from the article “John Snow”, Wikipedia, available at:

http://en.wikipedia.org/wiki/File:Snow-cholera-map-1.jpg.