In a seaside town, Astra was tidying up an abandoned observatory above the town library. She was fourteen years old and the keys to the heavy display cabinets of sky models. Rain hissed on the glass of the dome and the wind whistled through the wooden crevices. She liked the noise because it drowned out the hollow echoes of long school evenings. Dust, astronomers' notes and the smell of old paint waited in the empty desk. Under the lowest shelf she found a tin tea box and a brass watch. The second hand did not run evenly; it leapt forward, stepped back as if trying to count something. A map of the stars and an engraving glinted in the flap: Full moon only. Astra swallowed her saliva as she felt the warmth of the metal, as if the watch was breathing. On the edge of the flap someone had scratched a miniature lantern and three waves. On the stairs rumbled the footsteps of Maks, her upstairs neighbour and circle partner. The boy cmoched appreciatively, seeing the pinions and the tiny wind rose under the glass. - 'This is no ordinary watch,' he whispered, rubbing the wet windowsill with his hand. He claimed it was more like a compass for moments, not a regular timepiece. Astra gently moved the hand back five seconds, and the spilt tea began to return to the cup. Bubbles receded on the tablecloth like a film being played backwards. In the corner an old planetary model rustled, spinning the sun around its brass axis. For an hour they flicked through catalogues and yellowed old issues of the local newspaper. They came across a photograph of Professor Eugenia Twardowska, designer of a chronocompass for sailors in 1923. The caption proclaimed that the device synchronises itself with the light of the lighthouse and the phase of the moon. - 'Full moon today,' Maks remarked, pointing out the window where fog was cutting the beam of light. - 'We'll check for a time jump of more than five seconds before anyone comes back here. A note warned not to move fire or mirrors through the time jump. The lantern wailed low, and the town hall clock struck a full twelve times. Astra winded the mechanism, setting the wind rose to the constellation of Sail exactly. The air thickened like syrup, and the floor trembled as if the boat had bounced off the quay. There was a confusion of sounds: the sirens of a steam locomotive, the laughter of a century ago and the flutter of flags came in at once. All the contemporary lights went out, and the light was the colour of a sepia-toned postcard. Someone knocked on the side of the locked hatch, which had been bolted shut for years, and quietly called out Astra's name.