Lowell Deeds

The latest on real estate recordings and new technology from the Middlesex North Registry of Deeds in Lowell

January 19, 2007

The Ghost Map

by @ 12:32 pm. Filed under Technology, History

I just finished reading “The Ghost Map” by Steven Johnson. The book’s subtitle is “The Story of London’s Most Terrifying Epidemic and How It Changed Science, Cities and the Modern World.” In late August 1854, the Soho neighborhood of London, then the world’s largest city with a population of more than 2 million, suffered a cholera epidemic. Within 48 hours, 10% of the neighborhood’s residents were dead. Besides providing an unnerving description of cholera’s impact on the human body, Johnson tells a fascinating tale of medical detective work. Up until then (and for some time thereafter), the best minds in medicine believed that cholera was spread by noxious odors and fumes. Of course, in 1850s London, there were plenty of them to provide ever-present support for that theory. One prominent physician, John Snow, believed that cholera was transmitted by impure drinking water (which is actually the case), but neither Snow nor any of his colleagues had isolated the cholera bacteria through the use of a microscope. Instead, Snow used sociology more than science to convince people of his theory. From interviewing survivors in the neighborhood he established that everyone who had died in the epidemic drank water from a popular public pump located on Broad Street in the middle of the neighborhood. But many who lived in the most wretched, smelly, infested homes in the neighborhood but who drank water from other sources had survived. To better argue his case, Snow obtained a map that showed the streets, houses and water pumps of the neighborhood. He then placed a black line for each victim within each house that had contained a victim of the epidemic (the “map” in the book’s title). The map showed the fatalities blossoming outwards from the Broad Street pump and provided overwhelming evidence that it was the transmitter of the disease. As Johnson notes in the book’s final chapter, the methodology used by Snow – graphically depicting events by placing points on a map – is an extremely effective way of problem solving, particularly in a densely packed urban setting. He notes the modern technology such as Google mapping software is perfectly suited for these types of projects. Be sure to visit the author’s website and follow the link to his YouTube-based mini-documentary about the story.

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