Snow's cholera map

Figure 4: Snow’s Map of Cholera in St James’s Parish (1854), showing the locations of individual deaths in relation to the location of the water pump. Published by C.F. Cheffins, Lith, Southhampton Buildings, London, England, 1854 in Snow, John. On the Mode of Communication of Cholera, 2nd Ed, John Churchill, New Burlington Street, London, England, 1855. Courtesy of Wikimedia Commons: http://en.wikipedia.org/wiki/File:Snow-cholera-map-1.jpg