Works
- On the Mode of Communication of Cholera, 2nd ed., 1855
In Thinking Tools
Known for
He argued that cholera spreads through contaminated water. In the second edition he compared London households supplied by the Southwark and Vauxhall company, which drew its water from the sewage-polluted Thames, with households supplied by the Lambeth company, which had moved its intake upriver, and found far higher death rates among the first.
Caveat: Calling the water-company comparison a difference-in-differences study is a later economists' reading; Snow did not set out the estimator.