Wednesday, October 27, 2010

The Ghost Map: the Story of London's Most Terrifying Epidemic-- and How It Changed Science, Cities, and the Modern World by Steven Johnson

We are accustomed to reading about how experts track down the origins of disease outbreaks from food poisoning to influenza to toxic contaminants. But this only became possible a century and a half ago when John Snow had the insight to plot cholera cases on a map of London that showed where there were public water pumps. Thus a map of the dead saved future lives.

Johnson retells and amplifies the well-known tale of how Snow pinpointed the contaminated water pump in London's Soho district in 1854. He adds to his narrative the story of the the local curate whose faith at first led him to doubt Snow's theory that cholera was spread by water. Eventually though, Reverend Henry Whitehead provided the conclusive evidence for that theory. Johnson contrasts these men with the officials who were convinced that bad air and noxious smells - miasma - were the cause of cholera outbreaks. Through the day to day details of the epidemic, Johnson demonstrates the scientific approach to problem-solving.

Johnson's purpose, however, is broader. He sees Snow's story as the turning point when urban life gained sufficient safety from disease to become sustainable. This is critical because urban living actually has a smaller carbon footprint than more dispersed populations. Johnson quotes Jane Jacobs extensively as he extols the benefits of cities. He examines modern threats and concludes that people will soon be able to cope with public health problems even in the huge shantytowns of the developing world.

More problematic these days are fanatics with bombs who can exploit population density as cholera did in Victorian times. And we are as clueless how to prevent such attacks as London was before Snow. Urban planners and anyone who votes on public policy would do well to read The Ghost Map which is available in both print and audio format. If you want to pursue Victorian scientists who solve great puzzles while wrestling with questions of faith, try Charles and Emma: the Darwins' Leap of Faith by Deborah Heiligman.

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