In 1854, a British anesthesiologist named John Snow made one of medical history’s  biggest discoveries. Flouting popular medical opinion of the time, he proved that cholera, a disease that had been devastating England in epidemic waves throughout the century was transmitted not by air, but by water. (Ann De Forest)

An important, easy to follow, article from the Navigator, Magazine published for customers of Holiday Inn Express. “Leave the towels and take the magazine.” I did. “Of Maps and Medicine” by Ann De Forest (October-November 1999): 4-7, describes how John Snow showed his hypothesis that cholera was spread by water and not air. He had already written a tract On the Mode of Communication of Cholera to persuade the London Council to clean up the water supply.

When the epidemic of 1854 hit, he tested his hypothesis by mapping the Brod Street area of London on a city map. Broad Street was hard hit by the epidemic. He marked each water pump and every cholera death on the map. The Broad Street pump showed that 500 deaths ravaged the area in 10 days. The Council ordered that the handle on the water pump be removed, and almost at once, deaths stopped.

Other persons in London, Exeter, and Leeds used mapping to gather evidence of the use and spread of cholera. Their speculations were not precise. De Forest gives details on the historical use of geography, cartography, and disease.

Disease prevention can be found in patterns and geographic locations as well as other sources. And, now with digital access and analysis, understanding how disease spreads can be conclusive.

Think on this--Snow identified the water pumps on his map and the precise location of the cholera deaths. Records were made of these facts. Cities in many countries kept mortality data–some published these items in the newspapers. Some recorded them in the city council minutes. Some provided separate ledgers where the deaths were entered by date and city precinct–or with exact addresses.

Smaller jurisdictions–towns and even villages– also kept similar records. Nashua, New Hampshire included such details in their town minutes from the late eighteenth century. Did your ancestor die of a public-monitored disease? You won’t know until you look.Your favorite genealogist, Arlene Eakle

PS You could begin your search by checking out this little-known article. It reproduces the map of London showing the Broad Street pumps and deaths.

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