Friday, June 26, 2026

Snow Job

Map of Soho showing cholera outbreak of 1854
When Dr. John Snow had the handles to London's Soho Broad Street public water pump removed in 1854 in an attempt to curb a cholera outbreak, he was exceeding his authority, but he was thoroughly convinced that the contaminated well was the cause. He had charted the cases on a local map and made the connection. The General Board of Health in London was not convinced. In their Report of 1854, they dismiss Snow and his theories. Commenting on the outbreak in Soho, they said:

In explanation of the remarkable intensity of this outbreak with very definite limits, it has been suggested by Dr. Snow, that the real cause of whatever was peculiar in the case lay in the general use of one particular well, situated at Broad Street in the middle of the district, and having (it was imagined) its waters contaminated with the rice-water evacuations of cholera patients. After careful inquiry, we see no reason to adopt this belief.

Schematic of the sewer lines near the Broad Street pump
It took a while for a medical community, firmly wed to the miasma theory of contagion, to catch up with Snow. We have an extensive report from 1874 detailing the water supply of Great Britain. It includes a map of Soho displaying Snow's plotting of cases as well as a detailed diagram of the sewers near the Broad Street pump. I guess they eventually decided there was some merit to his ideas and perhaps the outbreak was not caused by a disturbance in the grounds of the "Plague Pit" that released a miasma across the city.

The Board of Health report is in the LCSF at RC133 .G6 A34, and the 1874 report with the maps is here in Special Collections at Rare TD257 .G73 1874.