'Suck air out of a chamber?' Khalid said.
'Yes. Arrange a valve that lets air out but won't let it back in. Pump out what's there, and then hold any replacement air out.'
'Interesting! But what would remain in the chamber then?'
Iwang shrugged. 'I don't know. A void? A piece of the original void, perhaps? Ask the lamas about that, or your sufis. Or Aristotle. Or just make a glass chamber, and look in it.'
' I will,' Khalid said.
'And motion is easiest of all to study,' Iwang said. 'We can try all manner of things with motion. We can time this attraction of things to the Earth. We can see if the speed is the same up in the hills and down in the valleys. Things speed up as they fall, and this might be measurable too. Light itself might be measurable. Certainly the angles of refraction are constant, I've measured those already.'
Khalid was nodding. 'First this reverse bellows, to empty a chamber. Although surely it cannot be a true void that results. Nothingness is not possible in this world, I think. There will be something in there, thinner than air.'
'That is more Aristotle,' Iwang said. Natureabhors the void." But what if it doesn't? We will only know when we try.'
Khalid nodded. If he had had two hands he would have been rubbing them together.
The three of them walked out to the waterworks. Here a canal brought a hard flow from the river, its gliding surface gleaming in the morning light. The water powered a mill, which geared out to axles turning a bank of heavy metal working hammers and stamps, and finally the rotating bellows handles that powered the blast furnaces. It was a noisy place, filled with sounds of falling water, smashed rock, roaring fire, singed air; all the elements raging with transmutation, hurting their cars and leaving a burnt smell in the air. Khalid stood watching the waterworks for a while. This was his achievement, he was the one who had organized all the artisans' skills into this enormous articulated machine, so much more powerful than people or horses had ever been. They were the most powerful people in all the history of the world, Bahram thought, because of Khalid's enterprise; but with a wave Khalid dismissed it all. He wanted to understand why it worked.
He led the other two back to the shop. 'We'll need your glassblowing, and my leather and iron workers,' he said. 'The valve you mention could perhaps be made of sheep intestines.'
'It might have to be stronger than that,' said Iwang. 'A metal gate of some sort, pressed into a leather gasket by the suck of the void.'
'Yes.'
No Jinn in This Bottle
Khalid set his artisans to the task, and Iwang did the glassblowing, and after a few weeks they had a two part mechanism: a thick glass globe to be emptied, and a powerful pump to empty it. There were any number of collapses, leaks and valve failures, but the old mechanists of the compound were ingenious, and attacking the points of failure, they ended up with five very similar versions of the device, all very heavy. The pump was massive and lathed to newly precise fits of plunger, tube and valves; the glass globes were thick flasks, with necks even thicker, and knobs on the inside surfaces from which objects could be hung, to see what would happen to them when the air in the globe was evacu ated. When they solved the leakage problems, they had to build a rackand pinion device to exert enough force on the pump to evacuate the final traces of air from the globe. Iwang advised them not to create such a perfect void that they ended up sucking in the pump, the compound, or perchance the whole world, like jinni returning to their confinement; and as always, Iwang's stone face did not give them any clue as to whether he was joking or serious.
When they had the mechanisms working fairly reliably (occasionally one would still crack its glass, or break a valve), they set one on a wooden frame, and Khalid began a sequence of trials, inserting things in the glass globes, pumping out the air, and seeing what resulted. All philosophical questions on the nature of what remained inside the globe after the air was removed, he now refused to address. 'Let's just see what happens,' he said. 'It is what it is.' He kept big blank paged books on the table beside the apparatus, and he or his clerks recorded every detail of the trials, timing them on his best clock.
After a few weeks of learning the apparatus and trying things, he asked Iwang and Bahram to arrange a small party, inviting several of the qadi and teachers from the madressas in the Registan, particularly the mathematicians and astronomers of Sher Dor Madressa, who were already involved in discussions of ancient Greek and classical caliphate notions of physical reality. On the appointed day, when all those invited had gathered in the open walled workshop next to Khalid's study, Khalid introduced the apparatus to them, describing how it worked and indicating what they could all see, that he had hung an alarm clock from a knob inside the glass globe, so that it swung freely at the end of a short length of silk thread. Khalid cranked the piston of the rack and pinion down twenty times, working hard with his left arm. He explained that the alarm clock was set to go off at the sixth hour of the afternoon, shortly after the evening prayers would be sung from Samarqand's northernmost minaret.
'To be sure the alarm is truly sounding,' Khalid said, 'we have exposed the clapper, so that you can see it hitting the bells. I will also introduce air back into the globe little by little, after we have seen the first results, so you can hear for yourself the effect.'
He was gruff and direct. Bahram saw that he wanted to distance himself from the portentous, magical style he had affected during his alchemical transmutations. He made no claims, spoke no incantations. The memory of his last disastrous demonstration – his fraud must have been in his mind, as it was in everyone else's. But he merely gestured with his hand at the clock, which advanced steadily towards six.
Then the clock began to spin on its thread, and the clapper was visibly smashing back and forth between the little brass bells. But there was no sound coming from the glass. Khalid gestured: 'You might think that the glass itself is stopping the sound, but when the air is let back into the flask, you will see that it isn't so. First I invite you to put your car to the glass, so you can confirm that there is no sound at all.'
They did so one by one. Then Khalid unscrewed a stopcock that released a valve set in the side of the flask, and a brief penetrating hiss was joined by the muted banging of the alarm, which grew louder quickly, until it sounded much like an alarm heard from an adjoining room.
'It seems there is no sound without air to convey it,' Khalid commented.
The visitors from the madressa were eager to inspect the apparatus, and to discuss its uses in trials of various sorts, and to speculate about what, if anything, remained in the globe when the air was pumped out. Khalid was adamant in his refusal to discuss this question, preferring to talk about what the demonstration seemed to be indicating about the nature of sound and its transmission.
'Echoes might elucidate this matter in another way,' one of the qadis said. He and all the other visiting witnesses were bright eyed, pleased, intrigued. 'Something strikes air, pushes it, and the sound is a shock moving through the air, like waves across water. They bounce back, like waves in water bounce when they strike a wall. It takes time for this movement to cross the intervening space, and thus echoes.'
Bahram said, 'With the aid of an echoing cliff we could perhaps time the speed of sound.'
'The speed of sound!' Iwang said. 'Very nice!'
'A capital idea, Bahram,' Khalid said. He checked to make sure his clerk was noting all done or said. He unscrewed the stopcock all the way and removed it, so that they all heard the noisy clanging of the alarm as he reached into the flask to turn off the device. It was strange that the clapper should have been so silent before. He rubbed his scalp with his right wrist. 'I wonder,' he said, 'if we could establish a speed for light too, using the same principle.'
'How would it echo?' Bahram asked.
'Well, if it were aimed at a distant mirror, say… a lantern unveiled, a distant mirror, a clock that one could read very precisely, or start and stop, even better…'
Iw
ang was shaking his head. 'The mirror might have to be very far away to give the recorder time to determine an interval, and then the lantern flash would not be visible unless the mirror were perfectly angled.'
'Make a person the mirror,' Bahram suggested. 'When the person on the far hill sees the first lantern light, he reveals his, and a person next to the first person times the appearance of the second light.'
'Very good,' several people said at once. Iwang added, 'It may still be too fast.'
'It remains to be seen,' Khalid said cheerfully. 'A demonstration will clarify the issue.'
With that Esmerine and Fedwa wheeled in the ice tray and its 'demonstration of sherbets' as Iwang termed it, and the crowd fell to, talking happily, Iwang speaking of the thin sound of goraks in the high Himalaya where the air itself was thin, and so on.
The Khan Confronts the Void
So Iwang brought Khalid back out of his black melancholy, and Bahram saw the wisdom of Iwang's approach to the matter. Every day now, Khalid woke up in a hurry to get things done. The businesses of the compound were given over to Bahram and Fedwa and the old hands heading each of the shops, and Khalid was distracted and uninterested if they came to him with matters of that sort. All his time was taken by conceiving, planning, executing and recording his demonstrations with the void pump, and later with other equipment and phenomena. They went to the great western city wall at dawn when all was quiet, and timed the sound of wood blocks slapped together and their returning echoes, measuring their distance from the wall with a length of string one third of an li long. Iwang did the calculations, and soon declared that the speed of sound was something like two thousand li an hour, a speed that everyone marvelled at. 'About fifty times faster than the fastest horse,' Khalid said, regarding Iwang's figures happily.
'And yet light will be much faster,' Iwang predicted.
'We will find out.'
Meanwhile Iwang was puzzling over the figures. 'There remains the question of whether sound slows down as it moves along. Or speeds up for that matter. But presumably it would slow, if it did anything, as the air resisted the shock.'
'Noise gets quieter the further away it is,' Bahram pointed out. 'Maybe it gets quieter rather than slower.'
'But why would that be?' Khalid asked, and then he and Iwang were into a deep discussion of sound, movement, causation and action at a distance. Quickly Bahram was out of his depth, being no philosopher, and indeed Khalid did not like the metaphysical aspect of the discussion, and concluded as he always did these days: 'We will test it.'
Iwang was agreeable. Ruminating over his figures, he said, 'We need a mathematics that could deal not only with fixed speeds, but with the speed of the change of a speed. I wonder if the Hindus have considered this.' He often said that the Hindu mathematicians were the most advanced in the world, very far ahead of the Chinese. Khalid had long ago given him access to all the books of mathematics in his study, and Iwang spent many hours in there reading, or making obscure calculations and drawings, on slates with chalk.
The news of their void pump spread, and they frequently met with the interested parties in the madressas, usually the masters teaching mathematics and natural philosophy. These meetings were often contentious, but everyone kept to the ostentatiously formal disputation style of the madressa's theolo ical debates.
Meanwhile the Hindu caravanserai frequently sheltered booksellers, and these men called Bahram over to have a look at old scrolls, leatheror wood bound books, or boxes of loose leaved pages. 'Old One Hand will be interested in what this Brahmagupta has to say about the size of the earth, I assure you,' they would say grinning, knowing that Bahram could not judge.
'This one here is the wisdom of a hundred generations of Buddhist monks, all killed by the Mughals.'
'This one is the compiled knowledge of the lost Frengis, of Archimedes and Euclid.'
Bahram would look through the pages as if he could tell, buying for the most part by bulk and antiquity, and the frequent appearance of numbers, especially Hindu numbers, or the Tibetan ticks that only Iwang could decipher. If he thought Khalid and Iwang would be interested, he haggled with a firmness based on ignorance, 'Look this isn't even in Arabic or Hindi or Persian or Sanskrit, I don't even recognize this alphabet! How is Khalid to make anything of this?'
'Oh, but this is from the Deccan, Buddhists everywhere can read it, your Iwang will be very happy to learn this!'
Or, 'This is the alphabet of the Sikhs, their last guru invented an alphabet for them, it's a lot like Sanskrit, and the language is a form of Punjabi,' and so on. Bahram came home with his finds, nervous at having spent good money on dusty tomes incomprehensible to him, and Khalid and Iwang would inspect them, and either page through them like vultures, congratulating Bahram on his judgment and haggling skills, or else Khalid would curse him for a fool while Iwang stared at him, marvelling that he could not identify a Travancori accounting book full of shipping invoices (this was the Deccan volume that any Buddhist could read).
Other attention drawn by their new device was not so welcome. One morning Nadir Devanbegi appeared at the gate with some of the Khan's guards. Khalid's servant Paxtakor ushered them across the compound, and Khalid, carefully impassive and hospitable, ordered coffee brought to his study.
Nadir was as friendly as could be, but soon came to the point. 'I argued to the Khan that your life be spared because you are a great scholar, philosopher and alchemist, an asset to the khanate, a jewel of Samarqand's great glory.'
Khalid nodded uncomfortably, looking at his coffee cup. He lifted a finger briefly, as if to say, Enough, and then muttered, 'I am grateful, effendi.'
'Yes. Now it is clear that I was right to argue for your life, as word comes to us of your many activities, and wonderful investigations.'
Khalid looked up at him to see if he were being mocked, and Nadir lifted a palm to show his sincerity. Khalid looked down again.
'But I came here to remind you that all these fascinating trials take place in a dangerous world. The khanate lies at the centre of all the trade routes in the world, with armies in all directions. The Khan is concerned to protect his subjects from attack, and yet we hear of cannon that would reduce our cities' walls in a week or less. The Khan wishes you to help him with this problem. He is sure you will be happy to bring him some small part of the fruits of your learning, to help him to defend the khanate.'
'All my trials are the Khan's,' Khalid said seriously. 'My every breath is the Khan's.'
Nadir nodded his acknowledgement of this truth. 'And yet you did not invite him to your demonstration with this pump that creates a void in the air.'
'I did not think he would be interested in such a small matter.'
'The Khan is interested in everything.'
None of them could tell by Nadir's face whether he was joking or not.
'We would be happy to display the void pump to him.'
'Good. That would be appreciated. But remember also that he wishes specific help with cannonry, and with defence against cannonry.'
Khalid nodded. 'We will honour his wish, effendi.'
After Nadir was gone, Khalid grumbled unhappily. 'Interested in everything! How can he say that and not laugh!' Nevertheless he sent a servant with a formal invitation to the Khan, to witness the new apparatus. And before the visit occurred he had the whole compound at work, developing a new demonstration of the pump which he hoped would impress the Khan.
When Sayyed Abdul Aziz and his retinue made their visit, the globe that was to hold the void this time was made of two half globes, one edge mortised to fit the other precisely, with a thin oiled leather gasket placed between the two before the air was pumped out of the space between them, and thick steel braces for each globe, to which ropes could be tied.
Sayyed Abdul sat on his cushions and inspected the two halves of the globe closely. Khalid explained to him: 'When the air is removed, the two halves of the globe will adhere together with great strength.' He placed the halves toget
her, pulled them apart; placed them together again, screwed the pump into the one that had the hole for it, and gestured for Paxtakor to wind the pump out and in and out again, ten times. Then he brought the device over to the Khan, and invited him to try to pull the two halves of the globe apart.
It could not be done. The Khan looked bored. Khalid took the device out to the central yard of the compound, where two teams of three horses each were held waiting. Their draft harnesses were hooked to the two sides of the globe, and the horses led apart until the globe hung in the air between them. When the horses were steadied, still facing away from each other, the horseboys cracked their whips, and the two teams of horses snorted and shoved and skipped as they attempted to pull away; they skittered sideways, shifted, struggled, and all the while the globe hung from the quivering horizontal ropes. The globe could not be pulled apart; even little charges made by the horse teams only brought them up short, staggering.
The Khan watched the horses with interest, but the globe he seemed to disregard. After a few minutes of straining, Khalid had the horses stopped, and he unhooked the apparatus and brought it over to the Khan and Nadir and their group. When he unscrewed the stopcock, the air hissed back into the globe, and the two halves came apart as easily as slices of an orange. Khalid stripped out the smashed leather gasket.
'You see,' he said, 'it was the force of the air, or rather the pull of the void, that kept the halves together so strongly.'
The Khan got up to leave, and his retainers rose with him. It seemed he was almost falling asleep. 'So?' he said. 'I want to blow my enemies apart, not hold them together.' With a wave of his hand he left.
The Year of Rice and Salt Page 25
