The Year of Rice and Salt

Bahram and Paxtakor palmed the light wooden balls off, and they veered into the wind like bats.

'But this is absurd!' the Khan said. 'Cannonballs are much heavier, they cut through the wind like knives through butter!'

Khalid nodded. 'Very true, great Khan. We only use these wooden balls to exaggerate an effect that must act on any object, be it heavy as lead.'

'Or gold,' Sayyed Abdul Aziz joked.

'Or gold. In that case the cannonballs veer only slightly, but over the great distances they are cast, it becomes significant. And so one can never say exactly what the balls will hit.'

'This must ever be true,' Nadir said.

Khalid waved his stump, oblivious for the moment of how it looked. 'We can reduce the effect quite a great deal. See how the wooden balls fly if they are cast with a spin to them.'

Bahram and Paxtakor threw the balsam balls with a final pull of the fingertips to impart a spin to them. Though some of these balls curved in flight, they went farther and faster than the palmed balls had. Bahram hit an archery target with five throws in a row, which pleased him greatly.

'The spin stabilizes their flight through the wind,' Khalid explained. 'They are still pushed by the wind, of course. That cannot be avoided. But they no longer dart unexpectedly when they are caught on the face by a wind. It is the same effect you get by fletching arrows to spin.'

'So you propose to fletch cannonballs?' the Khan inquired with a guffaw.

'Not exactly, your Highness, but yes, in effect. To try to get the same kind of spin. We have tried two different methods to achieve this. One is to cut grooves into the balls. But this means the balls fly much less far. Another is to cut the grooves into the inside of the gun barrel, making a long spiral down the barrel, only a turn or a bit less down the whole barrel's length. This makes the balls leave the gun with a spin.'

Khalid had his men drag out a smaller cannon. A ball was fired from it, and the ball tracked down by the helpers standing by, then marked with a red flag. It was farther away than the bigger gun's ball, though not by much.

' It is not distance so much as accuracy that would be improved,' Khalid explained. 'The balls would always fly straight. We are working up tables that would enable one to choose the gunpowder by type and weight, and weigh the balls, and thus, with the same cannons, of course, always send the balls precisely where one wanted to.'

'Interesting,' Nadir said.

Sayyed Abdul Aziz Khan called Nadir to his side. 'We're going back to the palace,' said, and led his retinue to the horses.

'But not that interesting,' Nadir said to Khalid. 'Try again.'

Better Gifts for the Khan

'I suppose I should make the Khan a new suit of damasked armour,' Khalid said afterwards. 'Something pretty.'

Iwang grinned. 'Do you know how to do it?'

'Of course. It's watered steel. Not very mysterious. The crucible charge is an iron sponge called a wootz, forged into an iron plate together with wood, which yields its ash into the mix, and some water too. Some crucibles are placed in the furnace, and when they are melted their contents are poured into molten cast iron, at a temperature below that of complete fusion of the two elements. The resulting steel is then etched with a mineral sulphate of one kind or another. You get different patterns and colours depending on which sulphate you use, and what kind of wootz, and what kind of temperatures. This blade here,' he rose and took down a thick curved dagger with an ivory handle, and a blade covered with a dense pattern of crosshatchings in white and dark grey, 'is a good example of the etching called "Mohammed's Ladder". Persian work, reputed to be from the forge of the alchemist Jundi Shapur. They say there is alchemy in it.' He paused, shrugged.

'And you think the Khan…'

'If we systematically played with the composition of the wootz, the structure of the cakes, the temperatures, the etching liquid, then we would certainly find some new patterns. I like some of the swirls I've got with very woody steel.'

The silence stretched out. Khalid was unhappy, that was clear.

Bahram said, 'You could treat it as a series of tests.'

'As always,' Khalid said, irritated. 'But in this case you can only do things in ignorance of their causes. There are too many materials, too many substances and actions, all mixed together. I suppose it is all happening at a level too small to see. The breaks you see after the casting look like crystalline structures when they are broken. It's interesting, what happens, but there's no way to tell why, or predict it ahead of time. This is the thing about a useful demonstration, you see. It tells you something distinct. It answers a question.'

' We can try to ask questions that steelwork can answer,' Bahram suggested.

Khalid nodded, still dissatisfied. But he glanced at Iwang to see what he thought of this.