The Ghost Map

by Steven Johnson

In the summer of 1854, London teemed with humanity. With a population of two million people, it was the most densely populated city on the planet, and the Berwick Street area of Soho, with 432 people per acre, was London's most densely populated subdistrict. This is where The Ghost Map unfolds.

Chapter One of Steven Johnson's account of London's 1854 cholera epidemic is titled, "The Night-Soil Men," referring to those urban scavengers who made their living gathering up human excrement - from outdoor privies, sewers, cesspools, and even the Thames, where much of the human waste was eventually desposited - and selling it for fertilizer in more rural areas.

Yes, London in the mid 19th century was knee-deep in shit, which Johnson attributes to a number of factors, not the least of which was the introduction of the water closet (WC):

"Water closets were a tremendous breakthrough as far as quality of life was concerned, but they had a disastrous effect on the city's sewage problem. Without a functioning sewer system to connect to, most WCs simply flushed their contents into existing cesspools, greatly increasing their tendency to overflow."

These overflowing cesspools polluted the basements of many of London dwellings, the Thames, and, to the great misfortune of those who died in the cholera epidemic of 1854, the wells that provided the city dwellers their drinking water. Just outside of 40 Broad Street was the Broad Street pump, revered for the quality of water that it supplied the nearby residents. In fact, Soho residents closer to other pumps often walked the few extra blocks just to get some of that good Broad Street water.

40 Broad Street also happened to be the home of Thomas and Sarah Lewis, a London policeman and his wife who on the night of August 28, 1854 tended to their baby girl, who was vomiting and "emitting wattery, green stools that carried a pungent smell." Late into the night, Sarah took the baby's fouled cloth diapers and soaked them in a bucket of water, a bucket that she later took downstairs to empty into the cesspool in front of their house and only a few yards distant from the Broad Street pump.

Johnson maps the spread of cholera through the Soho neighborhood, much as his central characters do. John Snow, a noted doctor, and Henry Whitehead, a well-liked clergyman, both spent the ensuing days walking the neighborhood. Whitehead, with his widespread and intimate familiarity with the parish denizens, administered to the sick and consoled the families; Snow, the scientist, mapped the epidemic, house by house, victim by victim in his search for the disease's source. The prevalent theory of the day was that the foul smells that pervaded London were actually sources of disease. Snow thought differently. He had long believed that cholera was not airborne but waterborne, and in his daily perambulations, collections and queries in Soho's stricken streets and homes, he intended to prove it.

The Ghost Map is not merely a surprisingly detailed and interesting reconstruction of a cholera epidemic in 1854. Johnson, the author of , remains fascinated with complexity and systems theory, and he approaches the outbreak that summer not only from the human perspective but also from that of the bacterium, V. cholerae, and the metropolis, London itself. The Ghost Map explores how London, "a creature with a volition of its own," ended up with two million people inside of a thirty-mile circumfrence; how the interconnectivity of V. cholerae allows it to transform a human body into a factory in which to reproduce itself; how John Snow's map of the cholera outbreak not only made him the father of epidemiology, but holds up more than 150 years later as a masterpiece of information design; and how modern metropolises, as a result of the work of Snow and Whitehead, are not only centers of creativity and production, but are also some of the most healthy and environmentally friendly communities in the world.

Steven Johnson's  multidisciplinary expertise and great story-telling make The Ghost Map a quick and compelling read.