The Ghost Map: The Story of London’s Most Terrifying Epidemic—and How It Changed Science, Cities, and the Modern World

As this chapter makes clear, the vestry investigative team’s findings were not vindicated right away. The miasma theory of cholera transmission continued to be a popular one for some years after the 1854 outbreak, and it lost influence by degrees rather than all at once. An elaborate sewer system (one that remains today) was constructed in London by the engineer Joseph Bazalgette; however, it was constructed in response to what was known as “the Great Stink” of 1858. This was a confluence of an unusually hot summer and the stink of the polluted Thames River.

There was then a second and final outbreak of cholera in London in 1866. While John Snow had already died—at age 45, and during the time of the Great Stink—he was posthumously vindicated by the investigation into this outbreak, which revealed its source to be a contaminated reservoir. The investigation was conducted by William Farr, and also by Henry Whitehead, who would live to see his friend’s waterborne theory of cholera transmission take hold.

This chapter discusses the long-reaching influence of Snow’s discovery and methodology on our lives today, suggesting that the latter was almost as important as the former.