A signal on the screen reads the gap between the reader’s body and a river that hasn’t touched daylight since the eighteenth century. The Fleet still runs — under Hampstead, under King’s Cross, under Clerkenwell — carrying the water it always carried, arched over and forgotten by the streets built on top of it.
The signal warms as the reader nears the buried course and cools as they drift from it, the way a hand searches for something underfoot. Along the route, nineteen points mark where the river once surfaced, or still does — a spring, a grating, a flood plain, an outfall visible only at low tide. Standing close enough to one releases what happened there.
There is no route drawn on the ground. Only a temperature, a bearing, and — under the right grating, after rain — the sound of it, still moving.
Work in progress — currently traced for the River Fleet, Hampstead Heath to Blackfriars.