Iron Winter

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?’