Wednesday was the first day of the semes­ter at UC Berkeley, where I attended the first lec­ture in my Visualization course. In it, the pro­fes­sor was oblig­ated to men­tion John Snow’s 1854 map of cholera deaths near the Broad Street pump in London.

It’s a land­mark work in the fields of both visu­al­iza­tion and epi­demi­ol­ogy. But I was still sur­prised when, the next day, explor­ing my local used book­store, I came across The Ghost Map, a book that recounts every detail of the epi­demic and Snow’s path toward dis­cov­er­ing its means of trans­mis­sion. I’m look­ing for­ward to read­ing about how Snow came upon the insight to use a visu­al­iza­tion — a map, in this case — to con­vince oth­ers of his the­ory that the dis­ease was car­ried in water, and that the Broad Street pump was the source of so many infec­tions. (In case you haven’t heard the story, his visual argu­ment was a suc­cess. The pump’s han­dle was removed, so the peo­ple had to look else­where, to uncon­t­a­m­i­nated sources, for water.)