punctuating the rhythm, iron against iron. He moved with a deliberate arachnoid slowness, giving the nosy and the idle time to disperse. Occasionally he was aware of watchers secreted behind metal pillars or grilles, spying on him, thinking themselves discreet. More often than not he knew with certainty that he went about his errands unobserved. In the long years of his service to Quaiche, one thing had been made clear to the cathedral populace: Grelier’s business was not a matter for the curious.
But sometimes those who fled from him were doing so for reasons other than the edict to keep their noses out of his work.
He reached a spiral staircase, a helix of skeletal iron plunging down into the clanking depths of Motive Power. The staircase was ringing like a struck tuning fork. Either it was picking up a vibration from the machines below or someone had just employed it to get away from Grelier.
He leant over the balustrade, peering down the corkscrewing middle of the staircase. Two turns below, pudgy fingers slipped urgently along the handrail. Was that his man? Very probably.
Humming to himself, Grelier unlatched the protective gate that allowed entry to the stairwell. He flipped it shut with the sharp end of his cane and began to descend. He took his time, allowing each pair of footfalls to echo before proceeding down to the next step. He let the cane
The machines in the lower levels sang more loudly as he approached them. There was no part of the cathedral where you couldn’t hear those grinding mechanisms, if there were no other sounds. But in the high levels the noise from the motors and traction systems had to compete with organ music and the permanently singing voices of the choir. The mind soon filtered out that faint background component.
Not here. Grelier heard the shrill whine of turbines, which set his teeth on edge. He heard the low clank and thud of massive articulated cranks and eccentrics. He heard pistons sliding, valves opening and closing. He heard relays chattering, the low voices of technical staff.
He descended, cane tapping, medical kit ready.
Grelier reached the lowest turn of the spiral. The exit gate squeaked on its hinges: it hadn’t been latched. Someone had been in a bit of a hurry. He stepped through the doorframe and placed his medical kit between his shoes. He took the key from his breast pocket and locked the gate, preventing anyone from ascending from this level. Then he picked up the medical kit and resumed his leisurely progress.
Grelier looked around. There was no sign of the fugitive, but there were plenty of places where a man might hide. This did not concern Grelier: in time, he was bound to find the pudgy-fingered absconder. He could allow himself a few moments to look around, take a break from his usual routine. He did not come down here all that often, and the place always impressed him.
Motive Power occupied one of the largest chambers of the cathedral, on the lowest pressurised level. The chamber ran the entire two-hundred-metre length of the moving structure. It was one hundred metres wide and fifty metres from floor to magnificently arched ceiling. Machinery filled much of the available volume, except for a gap around the walls and another of a dozen or so metres below the ceiling. The machinery was immense: it lacked the impersonal, abstract vastness of starship mechanisms, but there was something more intimate and therefore more personally threatening about it. Starship machinery was vast and bureaucratic: it just didn’t notice human beings. If they got on the wrong side of it they simply ceased to exist, annihilated in a painless instant. But as huge as the machinery in Motive Power was, it was also small enough to notice people. If they got in the way of it they were liable to find themselves maimed or crushed.
It wouldn’t be painless and it wouldn’t be instantaneous.
Grelier pushed his cane against the pale-green carapace of a turbine. Through the cane he felt the vigorous thrum of trapped energies. He thought of the blades whisking round, drawing energy from the superheated steam spewing from the atomic reactor. All it would take was a flaw in one of the blades and the turbine could blow apart at any instant, bringing whirling, jagged death to anyone within fifty metres. It happened now and then; he usually came down to clean up the mess. It was all rather thrilling, really.
The reactor — the cathedral’s atomic power plant — was the largest single chunk of machinery in the chamber, housed in a bottle-green dome at the rear end of the room. The kindest thing you could say about it was that it worked and it was cheap. There was no nuclear fuel to be mined on Hela, but the Ultras provided a ready supply. Dirty and dangerous, maybe, but more economical than antimatter and easier to work with than a fusion power plant. They had done the calculations: refining local ice to provide fusion fuel would have required a pre- processing plant as large as the entire existing Motive Power assembly. But the cathedral had already grown as big as it ever could, given the dimensions of the Way and the Devil’s Staircase. Besides, the reactor worked and supplied all the power that the cathedral required, and the reactor workers didn’t get sick all that often.
From the reactor’s apex sprouted a tangle of high-pressure steam pipes. The gleaming silver intestines traversed the entire chamber, subject to inexplicable hairpin bends and right angles. They fed into thirty-two turbines, stacked atop one another in two rows, each row eight turbines long. Catwalks, inspection platforms, access tunnels, ladders and equipment elevators caged the whole humming mass. The turbines were dynamos, converting the rushing steam into electrical power. They fed the electrical energy into the main traction motors, twenty-four of them squatting atop the turbines in two rows of twelve. The traction motors in turn converted the electrical energy into mechanical force, propelling the great cranked and hinged mechanisms that ultimately moved the cathedral along the Way. At any one time only ten of the twelve motors on one side were doing any work: the spare set was idling, ready to be connected into use if another motor or set of motors needed to be taken offline for overhaul.
The mechanisms themselves passed overhead, extending from the traction motors to the walls on either side. They penetrated the walls via pressure-proofed gaskets positioned at the precise rocking points of the main coupling rods. The gaskets were troublesome, Grelier gathered: they were always failing and having to be replaced. But somehow or other the mechanical motion generated inside the Motive Power chamber had to be conveyed beyond the walls, into vacuum.
Above him, with a dreamlike slowness, the coupling rods swept back and forth and up and down in orchestrated waves, beginning at the front of the chamber and working back. A complicated arrangement of smaller cranks and eccentrics connected the rods to each other, synchronising their movements. Aerial catwalks threaded between the huge spars of thrusting metal, allowing workers to lubricate joints and inspect failure points for metal fatigue. It was risky work: one moment of inattention and there’d be lubrication of entirely the wrong sort.
There was more to Motive Power, of course. A lot more. Somewhere there was even a small foundry, working day and night to fabricate replacement parts. The largest components had to be made in Wayside plants, but it always took time to procure and deliver such replacements. The artisans in Motive Power took great pride in their ingenuity when it came to fixing something at short notice, or pressing a part into service for a different function than intended. They knew what the bottom line was: the cathedral had to keep moving, no matter what. No one was asking the world of them — it only had to move a third of a metre a second, after all. You could crawl faster than that, easily. The point was not the speed, but that the cathedral must never, ever stop.
‘Surgeon-General, might I help you?’
Grelier tracked the voice to its source: someone was looking down at him from one of the catwalks above. The man wore the grey overalls of Motive Power, and was gripping the handrail with oversized gloves. His bullet- shaped scalp was blue with stubble, a filthy neckerchief around his collar. Grelier recognised the man as Glaur, one of the shift bosses.
‘Perhaps you could come down here for a moment,’ Grelier said.
Glaur complied immediately, traversing the catwalk and vanishing back into the machinery. Grelier tapped his cane idly against the cleated metal floor, waiting for the man to make his way down.
‘Something up, Surgeon-General?’ Glaur asked when he arrived.
‘I’m looking for someone,’ Grelier told him. No need to say why. ‘He won’t belong down here, Glaur. Have you seen anyone unexpected? ’
‘Like who?’
‘The choirmaster. I’m sure you know the fellow. Pudgy hands.’
