The Year of Rice and Salt

'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.'

The Khan heard this and was not amused. 'You're suggesting we pile earth all around Samarqand? Impossible! It would be too ugly! The other khans and emirs would laugh at us. We cannot live like ants in an anthill!'

Khalid turned to Nadir, his face a polite blank.

'Next?' Nadir said.

'Of course. Now see, we have determined that at the distances a gun can cast a ball, it cannot shoot straight. The balls are tumbling through the air, and they can spin off in any direction, and they do.'

'Surely air cannot offer any significant resistance to iron,' Nadir said, sweeping a hand in illustration.

'Only a little resistance, it is true, but consider that the ball passes through more than two li of air. Think of air as a kind of thinned water. It certainly has an effect. We can see this better with light wooden balls of the same size, thrown by hand so you can still see their movement. We will throw into the wind, and you can see how the balls dart this way and that.'