The first problem in talking about London is deciding where it begins or ends. In 1907, Clarence Rook tried to walk across it, but gave up at nightfall in Wanstead Flats, where he could still see houses stretching "all the way to Romford". It was about 17 miles across at the time. A century earlier it spanned only five miles, but the fringes were such a no-man's land of rubbish, shanties, animal-traders, brick ovens and heaps of cinders and hop-husks that one could hardly say whether this was London or not.
Jerry White has compared this zone, in his study of the 19th century city, to "necrotic tissue stealing remorselessly outwards from an unhealed wound."
His new book traces the story back to the 18th century. As with his previous two volumes - he started with the 20th century - he shows us a terrible and magnificent metropolis, in a study both panoramic in scope and microscopic in detail. As the 18th century opened, London was still picking up the pieces after the 1666 Great Fire. Construction was everywhere, so that one could hardly navigate the streets for scaffolding.
London would increasingly become a grandiose, modern city, but it also continued to be a site of medieval squalor.
One of the worst areas was around Westminster Abbey and the Houses of Parliament, where hovels crept up to the Abbey itself and slumped against its walls.
Many roads either had no name at all, or were called things like Rotten Row, Dirty Lane, Foul Lane, Dark Entry and Pissing Alley.
In these dire streets, dire things happened. Muggings, assaults and burglaries were frequent, and punishments were severe at the hands of the mob as well as of authority.
In the opening scene, we see a vengeful crowd drag the hated informant John Waller from a pillory almost before the manacles are fastened, choke him with soot, slash him with knives, and beat him to death with cauliflower stalks.
For other offenders, London was a city of prisons: it had several dozen places of confinement for felons and debtors.
As White shows, it was a city of freedom as well as constraint. Journalism and the arts flourished, as did trade. By 1792 London had 62 private banks.
Eighteenth century London is arranged chronologically and thematically, so that we advance steadily through the century as we dip into one topic after another: money, work, culture, sex.
The scale of White's research is thrice impressive considering that he has now mastered three centuries of London life.
In the acknowledgments, White admits that he has had much help from the internet, which is particularly rich in 18th century material.
In different hands, such a web trawl could have resulted in a soulless book, but White makes thoughtful connections, and looks for meaning and individuality in all his stories.
As his book unfolds, London gradually changes, so that by the end it has almost grown into 19th-century self: still a harsh mixture of imprisonment and freedom, but also a stouter, cleaner, better lit and more charitable place.