'A Court for King Cholera', 1852.

'A Court for King Cholera', 1852. A scene typical of the crowded, unsanitary conditions in London slums. Cholera first appeared in Britain in 1831, and outbreaks occurred regularly in London in the mid 19th century. Its relationship with contaminated water was not understood until established by John Snow (1813-1858). Snow published his theory in a pamphlet in 1849, but did not prove his findings to be correct until another epidemic occurred in 1854. His work led to legislation paving the way for dramatic improvements in all aspects of public health provision. Cartoon from Punch. (London, 25 September 1852). (Photo by Ann Ronan Pictures/Print Collector/Getty Images)