He looked at Khalid. 'Do you see what I mean?'

'Maybe,' Khalid said. 'You propose to chart movement with numbers.'

'Yes, and also the movement within movement, changes in speed, you know, which must always be occurring in this world, as there is resistance or encouragement.'

'Resistance of air,' Khalid said luxuriously. 'We live at the bottom of an ocean of air. It has weight, as the mercury scales have shown. It bears down on us. It carries the beams of the sun to us.'

'Which warm us,' Bahram added.

The sun cracked the distant mountains to the east, and Bahram said, 'All praise and thanks to Allah for the glorious sun, sign in this world of his infinite love.'

'And so,' Khalid said, yawning hugely, 'to bed.'

A Demonstration of Flight

Inevitably, however, all their various activities brought them another visit from Nadir Devanbegi. This time Bahram was in the bazaar, sack over his shoulder, buying melons, oranges, chickens and rope, when Nadir suddenly appeared before him with his personal bodyguard. It was an event Bahram could not regard as a coincidence.

'Well met, Bahram. I hear you are busy these days.'

'Always, effendi,' Bahram said, ducking his head. The two bodyguards were eyeing him like falcons, wearing armour and carrying long barrelled muskets.

'And these many fine activities must include many undertaken for the sake of Sayyed Abdul Aziz Khan, and the glory of Samarqand?'

'Of course, effendi.'

'Tell me about them,' Nadir said. 'List them for me, and tell me how each one is progressing.'

Bahram gulped apprehensively. Of course Nadir had nabbed him in a public place like this because he thought he would learn more from Bahram than from Khalid or Iwang, and more in a public space, where Bahram might be too flustered to prevaricate.

So he frowned and tried to look serious but foolish, not really much of a stretch at this moment. 'They do much that I don't understand, effendi. But the work seems to fall roughly into the camps of weapons and of fortifications.'

Nadir nodded, and Bahram gestured at the melon market they were standing beside. 'Do you mind?'

'Not at all,' Nadir said, following him in.

So Bahram went to the honey and muskmelon trays, and began to lift some onto the scale. He was certainly going to get a good deal for them with Nadir Devanbegi and his bodyguards in the shop!

'In weapons,' Bahram improvised as he pointed out the red melons to a sullen seller, 'we are working on strengthening the metal of cannon barrels, so they can be both lighter and stronger. Then again, we have been conducting demonstrations of the flight of cannonballs in different conditions, with different gunpowders and guns, you know, and recording them and studying the results, so that one would be able to determine where precisely one's shots would land.'

Nadir said, 'That would be useful indeed. Have they done that?'

'They are working on it, effendi.'

'And fortifications?'

'Strengthening walls,' Bahram said simply. Khalid would be furious to hear of all these promises Bahram was so rashly making, but Bahram did not see any good way out of it, except to make his descriptions as vague as possible, and hope for the best.

'Of course,' Nadir said. 'Please do me the courtesy of arranging one of these famous demonstrations for the court's edification.' He caught Bahram's eye to emphasize this was not a casual invitation. 'Soon.'

'Of course, effendi.'

'Something that will get the Khan's attention as well. Something exciting to him.'

'Of course.'

Nadir gestured with a finger to his men, and they moved off through the bazaar, leaving behind a swirling wake in the press of the crowd.

Bahram heaved a deep breath, wiped his brow. 'Hey there,' he said sternly to the seller, who was slipping a melon off the scale.

'Not fair,' the seller said.

'True,' Bahram said, 'but a deal's a deal.'

The seller couldn't deny it; in fact he grinned under his moustache as Bahram sighed again.

Bahram went back to the compound and reported the exchange to Khalid, who growled to hear it, as Bahram knew he would. Khalid finished eating his evening meal in silence, stabbing chunks of rabbit out of a bowl with a small silver prong held in his left hand. He put the prong down and wiped his face with a cloth, rose heavily. 'Come to my study and tell me exactly what you said to him.'

Bahram repeated the conversation as closely as he could, while Khalid spun a leather globe on which he had tried to map the world. Most of it he had left blank, dismissing the claims of the Chinese cartographers he had studied, their golden islands swimming about in the ocean to the east of Nippon, located differently on every map. He sighed when Bahram finished. 'You did well,' he said. 'Your promises were vague, and they follow good lines. We can pursue them more or less directly, and they may even tell us some things we wanted to know anyway.'

'More demonstrations,' Bahram said.

'Yes.' Khalid brightened at the thought.

In the weeks that followed, the furore of activity in the compound took a new turn. Khalid took out all the cannons he had obtained from Nadir, and the loud booms of the guns filled their days. Khalid and Iwang and Bahram and the gunpowder artisans from the shop fired the big things west of the city on the plain, where they could relocate the cannonballs, after shots aimed at targets that were very seldom struck.

Khalid growled, picking up one of the ropes they used to pull the gun back up to the mark. 'I wonder if we could stake the gun to the ground,' he said. 'Strong ropes, thick stakes… it might make the balls fly farther.'

' We can try it.'

They tried all manner of things. At the end of the days their ears rang with reverberations, and Khalid took to stuffing them with cotton balls to protect them some little bit.

Iwang became more and more absorbed in the flights of the cannonballs. He and Khalid conferred over mathematical formulas and diagrams that Bahram did not understand. It seemed to Bahram they were losing sight of the goal of the exercise, and treating the gun merely as a mechanism for making demonstrations of motion, of speed and the change of speed.

But then Nadir came calling with news. The Khan and his retinue were to visit the next day, to witness improvements and discoveries.

Khalid spent the entire night awake in his study, making lists of demonstrations to be considered. The next day at noon everyone congregated on the sunny plain beside the Zeravshan River. A big pavilion was set up for the Khan to rest under while he observed events.

He did so lying on a couch covered with silks, spooning sherbet and talking with a young courtesan more than watching the demonstrations. But Nadir stood by the guns and watched everything very closely, taking the cotton out of his ears to ask questions after every shot.

'As to fortifications,' Khalid replied to him at one point, 'this is an old matter, solved by the Frengis before they died. A cannonball will break anything hard.' He had his men shoot the gun at a wall of dressed stone that they had cemented together. The ball shattered the wall very nicely, and the Khan and his party cheered, although as a matter of fact both Samarqand and Bokhara were protected by sandstone walls much like the one that had just fallen.

' Now,' Khalid said. 'See what happens when a ball of the same size, from the same gun loaded with the same charge, strikes the next target.'

This was an earthen mound, dug with great effort by Khalid's expuffers. The gun was fired, the acrid smoke cleared; the earthen mound stood unchanged, except for a barely visible scar at its centre.

'The cannonball can do nothing. It merely sinks into the earth and is swallowed up. A hundred balls would make no difference to such a wall. They would merely become part of it.'