Owl, sphere and triangle on forearms

The sphere came back from the restorer on Tuesday with its meridian ring straightened, and Mr Ashdown made me carry it up to the attic myself, which I took as a compliment until I saw the state of the stairs. It is the old armillary from the Lamb Street shop, the one with a small numeral three scratched beside the equator where somebody once counted something. He will not say what. He says the owl knows.

The owl is real, or was. It lives in the clock tower of St Agnes, which is why the night watchman leaves the hatch open for it, and every evening at half past nine it comes out over the wet roofs and drops past the lamps on Cutler Row. Last Thursday it landed on the sill of the workshop window, looked at the sphere for a long while, then went back out into the rain without taking the mouse I had left for it.

Ashdown says the triangle at the base is the only honest shape in the room, because it cannot fall over unless someone pushes it. The fox and the rabbit sit beside it because they are the ones who wait for the owl to finish. I have started to think he is teasing me. Nothing in this city runs in a straight line, yet he keeps measuring the streets with dividers and a pencil stub, as though he is trying to pin them down.

Last night I took the sphere down, set the three to the north star through the skylight, and turned the rings until the shadows lined up across the floor. For a minute the whole room was circles. Then the owl dropped out of the dark, settled on the brass, and I saw it had a folded note in its talons. It let the note fall at my feet. The hand was Ashdown's: Come at midnight. Bring the dividers. We have three hours before the tide turns.

Your loving brother, Tom