All three of them were quiet. Andrej rolled his eyes from side to side, not comprehending a single word.

Isaac worked silently. He tried to imagine a city in the thrall of the Construct Council. He thought of it linked up to the little crisis engine, building more and more of the engines on an ever-increasing scale, connecting them up to its own fabric, powering them with its own thaumaturgical and elyctro-chymical and steampower. Monstrous valves hammering in the depths of the dump, making the fabric of reality bend and bleed with the ease of a Weaver’s spinnerets, all doing the bidding of that vast, cold intelligence, pure conscious calculation, as capricious as a baby.

He fingered the circuit-valve, shaking it gently, praying that its mechanisms were sound.

Isaac sighed and brought out the thick sheaf of programme cards the Council had printed. Each was labelled in the Council’s tottering typewritten script. Isaac looked up quizzically.

“It’s not yet ten, is it?” he said. Derkhan shook her head. “There’s still nothing in the air, is there? The moths aren’t out yet. Let’s be ready by the time they fly.”

He looked down and pulled the lever on the two chymical batteries. The reagents within mixed. The sound of effervescence was dimly audible, and there was a sudden chorus of chattering valves and barking outputs as current was released. The machinery on the roofscape snapped into life.

The crisis engine whirred.

“It’s just calculating,” said Isaac nervously, as Derkhan and Yagharek glanced at him. “It’s not yet processing. I’m giving it instructions.”

Isaac began to feed the programme cards carefully into the various analytical engines before him. Most went to the crisis engine itself, but some to the subsidiary calculating circuits connected by little loops of cable. Isaac checked each card, comparing it with his notes, scribbling quick calculations before feeding it into any of the inputs.

The engines clattered as their fine ratcheting teeth slid over the cards, snapping into carefully cut holes, instructions and orders and information downloading into their analogue brains. Isaac was slow, waiting until he felt the click that signalled successful processing before removing each card and slotting in the next.

He kept notes, scrawling impenetrable messages to himself on ragged ends of paper. He breathed quickly.

Rain began to fall, quite suddenly. It was sluggish, huge drops falling indolently and breaking open, as thick and warm as pus. The night was close, and the glutinous rainclouds made it more so. Isaac worked fast, his fingers feeling suddenly idiotic, too large.

There was a slow sense of dragging, a weightiness that pulled at the spirit and began to saturate the bones. A sense of the uncanny, of the fearful and hidden, that rolled up as if from within, a billowing ink-cloud from the depths of the mind.

“Isaac,” said Derkhan, her voice cracking, “you have to hurry. It’s starting.”