He shuffled his little deck like a cardsharp. He sensed the minuscule jerks of the analytical engine through the fingertips of his left hand. He felt for faulty input, for broken teeth or stiff, unoiled moving parts that would corrupt or block his programmes. There were none. The man could not forebear from hissing triumphantly. The construct’s virus was entirely the result of information-feedback, and not any kind of hardware failure. That meant that the cards with which the man was plying the engine would all be read, their instructions and information loaded into the sophisticated steam-engine brain.

When he had pushed each carefully selected programme card into the input slot, each in considered order, he punched a brief sequence of buttons on the numbered keys wired up to the cleaning machine’s analytical engine.

The man closed the lid on the engine and resealed the construct’s body. He replaced the twisted screws which held the hatch in place. He rested his hands on the construct’s lifeless body for a moment. He heaved it upright, stood it on its treads. He gathered his tools.

The man stepped back into the center of the room.

“Um . . . ’Scuse me, squire,” he yelled.

There was a moment of silence, then Isaac’s voice boomed out.

“Yes?”

“I’m all done. Problems should be over. Just tell Mr. Serachin to load up the boiler with a bit of juice, then switch the old thing back on. Lovely models, the EKBS.”

“Yeah, I’m sure they are,” came the response. Isaac appeared at the railing. “Is there anything else I need to know?” he asked impatiently.

“No, guv, that’s about it. We’ll invoice Mr. Serachin within the week. Cheerio, then.”

“Right, bye. Thanks very much.”

“Don’t mention it, sir,” the man began, but Isaac had already turned and walked back out of sight.

The repairman walked slowly to the door. He held it open and looked back at where the construct lay face down in the shadows of the big room. The man’s eyes flickered momentarily upstairs to check that Isaac was gone, then he moved his hands to trace out some symbol like interlocking circles.

“Virus be done,” he whispered, before walking out into the warm noon.

Chapter 20

CHAPTER TWENTY

“What am I looking at?” asked Yagharek. As he held the diagram he cocked his head in a shockingly avian motion.

Isaac took the sheet of paper from him and turned it the right way up.

“This, old son, is a crisis conductor,” Isaac said grandly. “Or at least, a prototype of one. A fucking triumph of applied crisis physico-philosophy.”

“What is it? What does it do?”