Book Review: The Ghost Map by Steven Johnson

The Ghost Map is the most interesting book about raw sewage I’ve ever read! If you only read one book about poop in your entire life, this is the book to read.

The “ghost map” refers to the map on which Dr. John Snow plotted the deaths from the cholera outbreak in London in 1854. Cholera is a bacterial infection in the lower intestine that causes violent diarrhea until the sufferer dies of dehydration. If the victim can drink enough water, his body can usually fight off the infection. No one knew that, though. Cholera had an extremely high mortality rate in the last century.

Dr. Snow believed cholera was transmitted by contaminated water, but no one agreed with him. Most people agreed that cholera spread by miasma. Stinky air made you sick. With an idea like that, no one much bothered with the cleanliness of the water. London was pumping raw sewage into the Thames about as fast as it was pumping its drinking water out of the Thames.

The scientific method was still in its infancy. The idea that you should test your idea to see if you were right was almost insulting to the intelligentsia of the day. If everyone knew something to be true, there was no need to show it was true by independent research. ‘Miasmatists’ controlled public health measures because everyone had always known that bad smells caused disease. Dr. Snow wasn’t just up against a wrong idea; he was up against an entire way of thinking.

Doctor John Snow and Vicar Henry Whitehead tracked the deaths from this particular cholera outbreak to show that the Broad Street water pump was spreading cholera. With lists of the dead in hand, the two men knocked on doors, asking survivors if they had drunk from the Broad Street pump, or if the deceased had done so. They tracked down people who had fled the neighborhood, and asked them where they got their water. It was a laborious and intrusive bit of detective work, but it paid off. They convinced a government committee of the Broad Street pump’s danger. The committee shut off the pump, and the outbreak stopped.

When the committee had the pump excavated, they discovered that the cesspool of the neighboring apartment building was draining into the well. And yes, a young mother had washed her sick baby’s diapers in water she had thrown into the cesspool in the days before the baby died. There is no hint in the record if anyone every told that young mother that hundreds of people had died because she had cleaned up after her dying baby as best she could in the conditions that existed in London in 1854. I hope they didn’t tell her.

Over the next few decades, the idea that cholera came from sewage in the water gradually spread, and the government started to pay attention to water quality. Bazalgette designed a massive sewer system for London that was so well-done that London still uses the tunnels and design today (although the equipment has obviously been upgraded).

The Ghost Map is also a story about the history of cities. In 1854, life in a city was a chancy proposition because of poor sanitation, bad construction, and appalling working conditions. Society was holding its breath to see if cities were a viable way of life, or if humanity ought to scatter back to the farm. The verdict is in. Cities are here to stay; they’re going to get bigger; and they provide a better life than rural living does, even in third world countries that still have conditions from the 1850s in their cities.

Johnson wrote a fascinating account of disease, cities, and the scientific method. It was hard to put down, and I don’t often say that about a non-fiction book. I can’t recommend this book highly enough.

And I wasn’t kidding about the first paragraph. Johnson explains how poop was handled in London in 1854 before there were sewer systems. It’s enough to make you say a prayer of gratitude every time you flush your toilet.