Iron Winter n-3

by Stephen Baxter

  Pyxeas snorted. ‘Uzzia, Bolghai is studying properties of the air. We are all at the mercy of the weather, yes? And though I, Pyxeas, and the generations who went before me, have shown that the great cycles of the weather are dominated by astronomy, by the dipping and nodding of the world as it orbits the central fire, it is nevertheless the air that delivers that weather to us. So we study it too.

  ‘After all, invisible though it may be the air is real; it has weight and substance. You can feel it dragging into your lungs, you can use pumps to evacuate it from a chamber — we all felt its lack up on the roof of the world. And the air is made up of several component parts, which can be separated with sufficient ingenuity. This was first achieved by Northlander scholars. We know there is vital air, an air full of energy, which we suspect is the agent that supports combustion — and indeed the slower fire that burns in our bodies to sustain life. And then there is fixed air. This was first identified by a scholar at Etxelur called Cleomedes, of Greek descent, who studied the burning of charcoal in a closed vessel.’

  Bolghai said, ‘The scholars of Cathay have long shared their knowledge with Northland, a tradition I have sought, in my time, to maintain, or rather revive. I with my party was the first to travel to Northland after the conquests of the Great Khans. And, given the importance of the air to the weather which shapes all our destinies, as Pyxeas points out, we have continued its study here. Although Cathay scholars are perhaps of a more practical bent than those of Northland.’

  Pyxeas sighed. ‘True, true, but the first Wall-builders would cringe to hear you say it. That’s the legacy of Pythagoras and his Greeks, who could be a bit contemplative.’

  Bolghai gestured at his apparatus. ‘We have found ways to measure the presence and concentration of fixed air more precisely. For instance here, you see, the air from this chamber is fed through lime dissolved in water; it precipitates a kind of chalk whose weight we can determine. . The details are unimportant.’

  ‘Not to me, they’re not!’ thundered Pyxeas. ‘I want to examine every tube and valve, every seal and measuring gauge. Excellent experimental design,’ he said now, walking around the boxes. ‘Can you see it, Avatak? Why these empty boxes, for instance?’

  That was easy; Avatak had seen similar set-ups in Pyxeas’ own studies. ‘They are for comparison. A horse in this box, not in that box that’s otherwise the same; you can subtract one from the other to see what difference the horse makes.’

  ‘Exactly!’

  Bolghai said, ‘Of course the emissions and absorptions vary depending on the plant or beast enclosed, and indeed on its conditions — if the horse is agitated or not, resting or exercising, for instance. All these things we can study.’

  Uzzia asked, ‘Who is the man in the box?’

  Bolghai seemed puzzled by the question. 'Who? Why — he is the subject. I sent specifications to the slavers regarding size and weight and general health. I hope to extend the studies to compare different ethnicities, ages, health conditions — sex, of course. I am not concerned with who.

  ‘What is most important is the conclusion. Which is this.’ With the air of a showman he walked them past the compartments containing the grass, the grain. ‘Vegetables, plants, trees — as they grow these things absorb the fixed gas from the air. But if they are burned they release that gas again. Whereas animals, from sheep to pigs to men, they release the fixed gas as they breathe. All of this in the processes of their lives, you see — it seems accurate, as you say, Pyxeas, to think of life as a kind of slow burning, animal life at least. Plants and animals, absorption and release-’

  ‘Yes, yes. And together they shape the atmosphere — and it shapes them. But to what end, what end? And how does this relate to the longwinter? For somehow it must. .’

  ‘Quite so,’ Bolghai said. ‘To explore that I am also running studies of the physical properties of fixed air. Perhaps that will offer some clues. But the properties are subtle, the apparatus unwieldy and preliminary. Nevertheless I have some first results. We can proceed to that when we’re done here.’

  ‘Good, good,’ Pyxeas murmured. The two scholars wandered off, talking, debating.

  Servants stood by Uzzia and Avatak, heads bent, waiting for instructions.

  ‘I want to get out of here,’ whispered Avatak.

  ‘Yes. And I’ve got deals to do. We’ve delivered Pyxeas to his scholar; we’ve done our jobs for now. Let’s go.’

  42

  Uzzia wandered through Daidu, reacquainting herself with a city she’d visited once before. Avatak followed her, gradually finding his bearings.

  Within its double walls the city was laid out like a board game played by giants, the rectangle of walls enclosing a grid-pattern of streets, with tidy blocks of houses and inns and manufactories, temples and schools, all on a tremendous scale. Avatak, a boy from a chaotic land of ice and water, even having visited Northland’s mighty Wall, felt utterly out of place in this vision of stone and geometry.

  But the vision could be pleasing. You would turn a corner and come upon a park gleaming green in the late autumn sunshine, with animals apparently roaming loose: squirrels, ermine, deer, even stags. A river ran right through the city, and people walked its banks and crossed delicate bridges. The people were both Cathay and Mongol, the latter in their colourful silk tunics and coats. People spoke Mongol, or one of the tongues of Cathay, or a rapid language that Uzzia identified as Persian, a common tongue for the traders who came here.

  Some of the grander folk went on horseback. The cultured Cathay folk seemed to flinch at seeing horses inside a city, but the Mongols’ bond with their animals was indissoluble. Avatak saw one man ride along under a canopy of gold, carried by bearers who had to run alongside. Uzzia said this was probably a baron, one of the Khan’s top generals, who would command a hundred thousand men or more.

  In one place by the river Avatak saw a tower, four or five times taller than a man, with a small waterwheel at its side. On the top was a brass construction, a ring showing the constellations, models of sun and moon. It was a representation of the sky, driven by the waterwheel, like a tremendously expanded version of Pyxeas’ oracle. Perhaps the links between Cathay and Northland really were deep and ancient, Avatak thought.

  Uzzia said she wanted to go out of the city proper and into the suburbs, where the livelier markets were to be found. So they made their way to the northern wall, heading for a gate. The gates themselves were huge, like fortresses built into the walls, each hosting hundreds of soldiers. Uzzia spoke in her cursory Mongol to the guards, ensuring they could get back in later, even without Pyxeas’ paiza in their pockets. Beyond the gate they had to pass through the city’s outer layer of defences, over a moat filled with brackish water and then to an outer wall. There seemed to be a whole army of soldiers in rough camps in the space between the walls, with heaps of weapons, herds of the Mongols’ stocky ponies. ‘Not so much a city,’ murmured Uzzia as they walked, ‘as a fortress, and designed by Kublai to be that way. Well, I suppose it is inevitable; Old Hattusa was a fortress-city too, another capital of conquerors.’

  The suburb beyond the outer walls was a city in itself, but much more disorderly, crowded, with a pall of greasy smoke rising from a hundred fires. There was a steady stream of traffic through the gates, of pedestrians, horse riders, and carts drawn by bullocks and horses. Avatak noticed a line of people, men, women and children, all of them shabby-looking, strung out along the length of the outer wall, leading away from the gate. They were waiting for something handed out at the gate itself by a team of soldiers; more tough-looking troops patrolled the line, weapons ready, prepared for any trouble.

  Uzzia, evidently feeling more at home in this bustling market town, plunged into its narrow alleys. The houses here were of mud or sod bricks, and roofed by turf or wood slats. There was business being done everywhere, in inns, stores selling food or clothes or spices or precious goods, and brothels with exotic whores, both female and male, beckoning from doorways.
Uzzia soon found a tremendous central marketplace, crowded with stalls. Avatak was baffled by the masses of porcelain, silks, plums, watermelons, and a blizzard of paper money. But the marketplace backed onto a stockyard where animals, distressed and calling out, were being lined up in huge numbers for slaughter in the open air. Corpses dangled from hooks, and the cobbles were sticky with old blood. Avatak had gutted seals and flensed walruses; he was far from squeamish. But the sheer scale of this slaughter, however necessary to feed the hungry city, repelled him.

  With a word to Uzzia, he turned away and began to walk back towards the gate. He was curious about the line of people at the wall. When he came to the line he backtracked, trying to find the end, but the line stretched all the way to the corner of the wall’s rectangular layout, and back down the next side, and on out of his sight. There must be thousands of people in this one line, perhaps tens of thousands.

  He walked back along the line towards its head. Every so often the waiting horde would move forward in a great rippling movement that spread along the line, and people jostled, making sure their neighbours didn’t try to jump a space. There were always fights somewhere, and soldiers would leap in with clubs raised to sort it out. Whatever it was these people were waiting for, they needed it badly.

  The line ended at a simple table, manned by two officers and heavily guarded by a circle of troops. They backed onto a kind of storehouse built into the wall itself. The soldiers made a note of each supplicant’s name on a paper scroll, and then a bundle was handed over, wrapped in paper. The supplicant would hurry away with nods of obeisance and gratitude.

  ‘Bread,’ Uzzia murmured in his ear.

  Avatak glanced around, surprised she’d found him. ‘Bread? That’s all?’

  ‘A daily hand-out from the Khan. And they send grain from the city stores to the provinces too. Apparently they have been feeding twenty thousand people from the city alone this way. But the granaries are emptying and every day the dole is cut down a little more. Of course the soldiers are always well fed. We need to get back inside the city.’

  ‘Why?’

  ‘A messenger found me. There’s been an explosion at the palace.’

  ‘There’s been a what?’

  She grinned. ‘That rascal Pyxeas. You can’t leave him alone for a heartbeat, can you?’

  They were brought to another corner of the palace, a smaller laboratory. Here another elaborate experimental apparatus had been set up, on a lesser scale — stands and tubes and flasks and pipes, mirrors, small oil heaters. But this equipment had been scattered around the room. The carpet was scorched, the paint on the wall blistered. One servant seemed to have been injured, a weeping woman, and a doctor was tending to her burned arm. Soldiers stood around, looking shocked, dismayed, as well they might, Avatak supposed. The explosion, deep inside the home of the Khan himself, must have made them fear assassins, and, worse, the punishment they would receive if any harm came to the Khan or his family.

  And here was Pyxeas, a blissful smile on a soot-stained face, the fringe of white hair around his scalp vertical, his robe smeared black. Bolghai stood behind him, equally begrimed, rather more shamefaced. ‘Avatak!’ Pyxeas cried. ‘I hope you enjoyed your walk. You missed a bit of fun.’

  ‘I can see that. What were you making here — eruptors?’

  ‘Nothing of the sort! Though I can see you might have difficulty working it all out given that it’s lying in pieces everywhere. . Where is the gas tube, Bolghai?’

  ‘Over there,’ said the Mongol. ‘And there. Oh, and there’s a bit stuck in the ceiling, I think.’

  As the philosophers and their servants gathered the fragments of the broken apparatus, gradually Avatak pieced together what Bolghai had been attempting here.

  ‘What controls our weather?’ Pyxeas asked. ‘The sun, whose position in the sky as determined by astronomical considerations fixes the amount of heat delivered to the world — and the air, through which that heat must pass. But how does the sun’s heat pass through the air? How much of it is blocked — and how much trapped, as the thinnest linen blanket will trap some of the warmth of the body? That’s what this apparatus seeks to determine.’

  The core of it had been a long brass tube, held horizontally. One end of this was heated, either by reflected sunlight or an oil lamp. At the far end of the tube was a thin, upright glass flask containing oil; by seeing how the oil expanded and climbed up its flask you could tell how much heat was passed through the tube — or rather, through whatever was trapped inside.

  ‘Can you see?’ Pyxeas said, holding up a fragment of smashed-open tube. ‘The ends are sealed with rock salt, which passes heat without diminution. The tube can be evacuated altogether, emptied of any kind of air, or it can be blocked with metal plugs, so that virtually no heat passes. Thus we have a maximum and a minimum for the heat transfer. Then we can fill the tube with, well, whatever we like — ordinary air, fixed air, water vapour. And we can see how the various components of the air trap the heat differently.’

  ‘I think I see. And the conclusions?’

  ‘That the fixed air, even a trace of it, makes a very efficient blanket for the trapping of heat. Very efficient indeed.’

  Uzzia was scowling. ‘Bits of gas in a tube, mirrors and flames — how did you manage to make all this blow up?’

  ‘That took some doing,’ Pyxeas admitted ruefully. ‘And on my first day here too. But — patience, my dear. Philosophical understanding grows as a child learns to walk, with one uncertain step at a time. Of course all these results are preliminary and need to be confirmed, which we can begin to do once we get this apparatus rebuilt. Where is that craftsman of yours, Bolghai? Got something better to do, has he? And can’t we get these wretched soldiers out of here?’

  43

  High on the Wall, fisherman Crimm didn’t want to get too close to the balcony rail. The day was clear and bitterly cold, and the balcony was thick with ice, slick and slippery and bright in the low winter sun that hung in the southern sky, shining straight in his eyes. Plenty of opportunity to go tumbling off this balcony, to go skimming down the length of the incongruously cheerful banners that had been unfurled down the face of the Wall, and to smash his head open on the heaps of rubble at the foot, thus getting himself killed before the day’s action even started.

  Ayto, though, wasn’t troubled. He rested easy on the rail, arms folded, mittened hands stuck under his armpits, staring south, oblivious of the drop below. He waited calmly at Crimm’s side, just as they had so often faced a storm at sea about to fall on the Sabet.

  Now there was motion on the ice-bound land, far to the south, black specks crawling under a clear blue sky. People approaching the Wall.

  Ayto murmured, ‘Is it them?’

  ‘Not sure.’

  ‘They are coming up the Way, straight to Etxelur. .’

  Despite the obvious approach there was no call yet from the lookouts on the Wall parapet. Crimm wasn’t surprised. You didn’t last long at sea without sharp eyes, and the lookouts would do no better than a couple of fishermen, stranded since the loss of the Sabet. And of course there was always a chance of snow blindness on a bright day like this. To the south, as he looked out now, all of Northland to the far horizon was locked under a covering of ice and heaped-up snow, a panorama in white and black and blue and streaks of silver-grey where ice lay on deeper water. Across a world locked in ice the Wall itself strode, its tremendous face frost-cracked and strewn with icicles, yet standing against the winter as it had defied the sea for millennia. But perhaps it had all been for nothing, Crimm thought, for those whom the Wall had been built to protect were now preparing to attack it.

  Ayto stirred. ‘It’s them all right. It’s not just more nestspills. You can see the organisation. They’re moving as a pack. And there’s metal glinting.’

  ‘Weapons.’

  ‘That would be my guess,’ Ayto said drily.

  The lookouts woke up at last. Calls went up all along the Wall,
from the roof scouts, across the balconies and galleries. People emerged to take their places at the rails, grim-faced, scared, shivering with the biting cold, and yet determined to play their part in saving the Wall.

  Ywa joined the fishermen, coming out from the inner Wall to the balcony. The Annid of Annids’ quilted coat was open to the waist so that her bronze chest plate could be seen, a very ancient and battle-scarred relic. She allowed herself one glance at Crimm. He took her arm, squeezed it, out of sight of the rest. They rarely had time alone nowadays.

  ‘So they come,’ she said. ‘The scheme is working. They’ve ignored the other Districts and are heading straight for us, for Etxelur.’

  Ayto said, ‘They’re cold and they’re hungry, and even if they’ve got anybody with military experience they aren’t much more than a starving mob. They’re heading for the obvious signs of life-’

  ‘Which we kindly provided for them,’ Crimm said.

  The Wall had been closed to incomers for a month now, a dreadful truncation that had cut off Etxelur and the Annids from the population of Northland. There had been petty assaults on the Wall, easily repelled, but as the hunger mounted in the country everybody had expected a more substantial attack, and plans had been laid, strategies discussed. A central stretch of the Wall had been prepared. With much labour elaborate stone buildings built onto the Wall’s growstone face, themselves centuries old, had been smashed up and prised away to lie in rubble at the foot of the Wall, to make a defensive barrier against the invaders. With the superstructure gone the older growstone core lay exposed, pocked with holes and pits like eye sockets — and a bank of slogans had been revealed, in an archaic dialect, slogans written tall enough to be seen across the countryside:

  THE WALL STANDS!

  THE LOVE OF THE MOTHERS PROTECTS US ALL!

  THE TROJANS CANNOT PREVAIL!

  On seeing this, some historically minded folk had expressed nostalgia for the age of Milaqa and Qirum, when Northland had been able to unite against an easily recognised human enemy. Now the enemy was the world itself, and Northlanders turned on each other.