But industry had exploded in New Crobuzon, much of it bankrolled by those very families. Factories and docks budded and proliferated. Griss Twist, just across the river, enjoyed a short-lived boom of small machinofacture, with all the noise and stink that that entailed. It became the site of massive riverside tips. A new landscape of ruin and refuse and industrial filth was created, in a speeded-up parody of geological process. Carts dumped load after load of broken machines, rotting paper, slag, organic offal and chymical detritus into the fenced-off rubbish tips of Griss Twist. The rejected matter settled and shifted and fell into place, affecting some shape, mimicking nature. Knolls, valleys, quarries and pools bubbling with foetid gas. Within a few years the local factories had gone but the dumps remained, and the winds that blew in from the sea could send a pestilential stench over the Tar into Petty Coil.

The rich deserted their homes. Petty Coil degenerated in a lively fashion. It became noisier. Paint and plaster bubbled, desquamating grotesquely, as the massive houses became homes for more and more of New Crobuzon’s swelling population. Windows broke, were fixed roughly, broke again. As small food-shops and bakers and carpenters moved in, Petty Coil fell willing prey to the city’s ineluctable capacity for spontaneous architecture. Walls and floors and ceilings were called into question, amended. New and inventive uses were found for deserted constructions.

Derkhan Blueday made her way hurriedly towards this mess of abused, misused grandeur. She carried a bag close. Her face was set and miserable.

She came up over Cockscomb Bridge, one of the city’s most ancient edifices. It was narrow and roughly cobbled, with houses built into the very stones. The river was invisible from the centre of the bridge. On either side, Derkhan could see nothing but the squat, rough-edged skyline of houses nearly a thousand years old, their intricate marble façades crumbled long ago. Lines of washing stretched across the width of the bridge. Raucous shouted conversations and arguments bounced back and forth.

In Petty Coil itself, Derkhan walked quickly under the raised Sud Line and bore north. The river she had passed over bent sharply back on itself, veering towards her in an enormous S, before righting its course and heading east and down to meet the Canker.

Petty Coil was blurring with Brock Marsh. The houses were smaller, the streets narrower and more intricately twisted. Mildewing old houses tottered overhead, their steeply slanting roofs like capes slung over narrow shoulders, making them furtive. In their cavernous front rooms and central courtyards, where trees and bushes died as filth encroached, rude signs were plastered advertising scarabomancy and automatic reading and enchantment therapy. Here, the poorest or most unruly of Brock Marsh’s delinquent chymists and thaumaturges fought for space with charlatans and liars.