By turns thought-provoking and irritating, The Ghost Map meanders from its central story -- how an unorthodox physician found the source of a cholera epidemic that swept through London in 1854 -- into a host of other issues. Expecting a more straightforward account of the unraveling of this medical mystery, I set this book aside twice in frustration, bored with the author's tendency to stretch out the narrative, and particularly his repeated examination of the hold the "miasma paradigm" had upon medical minds in the mid nineteenth century. He can't seem to get over the fact that all manner of educated and otherwise reasonable people believed that disease was caused by noxious smells. His lengthy discussion of the bureaucratic obstacles faced by John Snow, the physician who linked cholera with contamination of drinking water with sewage, begins to wear thin about half-way through the book.
The Ghost Map certainly starts promisingly enough, with a description of Victorian London's hitherto unheralded "recyclers" - the "night-soil men," "mudlarks," rag-gatherers, bone-pickers and others who made a living scavenging in London's streets, rivers, and sewers. This is fascinating stuff -- who knew, for example, that such a person as a "pure finder" (dealer in dog shit, or "pure, which was used by tanners) existed? In this Dickensian world, an astonishing diverse array of second- (or third-) class citizens eked out a living on the margins.
From an examination of this nether world, Johnson then moves on to the slums of London, doing a crack-up job describing the cramped, horrid living conditions. He zeros in on one street and one family; a harried mother is caring for a sick infant, who eventually dies. The child suffers from virulent diarrhea and is wasting away. The mother washes the soiled diapers and tosses the dirty water in the cesspool just outside her door. The cesspool, in turn, oozes into a local well. The stage is set for the beginning of an epidemic.
Johnson is best when he describes this world, with its reeking slums. But he is inclined, frequently, to hare after philosophical questions, not the least of which is mankind's inability to see beyond the dominant scientific paradigms of the time. This bogs the narrative down. While Johnson has many interesting ideas and speculations, it's tiring to be taken on so many unresolved side journeys. It's not quite so interesting, for example, to read (at length) of John Snow's battles with pig-headed authorities, who are blind to the obvious link that Snow establishes between one particular source of contaminated water and the cholera epidemic. Nor was I particularly enthralled to read the minutia of Snow's statistical analysis he built for his case. Johnson also seems inordinately fond of the idea of a "map" as a grand organizing theme, one which he stretches out well past the 19th century in the final chapter.
Actually, the final chapter leaves Snow's London altogether and is something of an eye opener. Johnson discusses the role of cities in the modern world, as well as the gravest threats that mankind faces today. This chapter could well be a stand-alone essay. It made me think, ultimately, that this book would have made two excellent books -- one the tale of the cholera epidemic and the other of the social consequences of the rise of cities. As it is, putting them into one book, weaving between factual account and philosophical premise, was over-reaching a bit.