fields and land to one side and the other. It finds its way into wells and is drawn up to launder petticoats and be boiled for tea. It is sucked into root membranes, travels up cell by cell to the surface, is held in the leaves of watercress that find themselves in the soup bowls and on the cheeseboards of the county's diners. From teapot or soup dish, it passes into mouths, irrigates complex internal biological networks that are worlds in themselves, before returning eventually to the earth via a chamber pot. Elsewhere the river water clings to the leaves of the willows that droop to touch its surface and then, when the sun comes up, a droplet appears to vanish into the air, where it travels invisibly and might join a cloud, a vast floating lake, until it falls again as rain. This is the unmappable journey of the Thames.