The Ghost Map - The Story of London's Most Terrifying Epidemic
by Steven Johnson
Riverhead Books, HK$143
'If your stomach is up to it, your brain will benefit,' wrote John Gapper in his Financial Times review of The Ghost Map. Subtitled The Story of London's Most Terrifying Epidemic - and How It Changed Science, Cities, and the Modern World, Steven Johnson's book is an insightful, consilient and at times rather too vivid account of a cholera epidemic that occurred in August 1842. Cholera, although well known, was never a particular problem until 2.4 million people were crammed into an area of 77 square kilometres and was at the time thought to be carried by London's filthy air. The Ghost Map itself was a diagram drawn by physician John Snow, who was sure cholera 'was something you swallowed'. It showed that the 700 victims who died in Soho were all within a 28-metre radius of a single water pump in Broad Street. The pump handle was removed and the epidemic burned itself out. The source was finally traced by local curate Henry Whitehead to a cesspool leaching into the underground well - the dirty nappies of a baby dying of cholera had been tossed into the cesspool. Johnson is most informative, too, on excrement.