“It’s leaving,” Bahram said, and they looked up, slightly annoyed to be interrupted. While the rainbow had been bright, the sky under it had been distinctly lighter than the sky over it; now the inside and outside were the same shade of slate blue again.
The rainbow left the world, and they squelched back to the compound, Khalid cheering up with every step, many of them right into puddles, as he was still staring at Iwang’s chalkboard.
“So — so — well. I must admit, it is as neat as a proof of Euclid. Two refractions, two or three reflections — rain and sun, an observer to see — and there you have it! The rainbow!”
“And light itself, divisible into a banding of colours,” Iwang mused, travelling all together out of the sun. So bright it is! And when it strikes anything at all, it bounces off and into an eye, if there be an eye to see it, and whatever part of the band, hmm, how would that work . . . are the surfaces of the world all variously rounded, if you could but look at them close enough . . .”
“It’s a wonder things don’t change colour when you move,” Bahram said, and the other two went silent, until Khalid started laughing.
“Another mystery! Allah preserve us! They will just keep coming for ever, until we are one with God.”
This thought appeared to please him immensely.
He set up a permanent dark room in the compound, all boarded and draped until it was much darker than his study had been, with shuttered chinks in the east wall that could let in small shafts of light, and many a morning he was in there with assistants, running in and out, arranging demonstrations one way or another. One he was pleased enough with to invite the scholars of the Sher Dor Madressa to witness it, because it so neatly refuted Ibn Rashd’s contention that white light was whole, and the colours created by a prism an effect of the glass. If this were so, Khalid argued, then light twice bent would change colour twice. To test this, his assistants allowed sunlight in through the wall, and a first prism’s array was spread across a screen in the centre of the room. Khalid himself opened an aperture in the screen small enough only to allow the red part of the little rainbow through it, into a draped closet where it immediately encountered another prism, directing it onto another screen inside the closet.
“Now, if the bend of refraction caused by itself the change in colour, surely the red band would change at this second refraction. But look: it remains red. Each of the colours holds when put through a second prism.”
He moved the aperture slowly from colour to colour, to demonstrate. His guests crowded around the door of the closet, examining the results closely.
“What does this mean?” one asked.
“Well, this you must help me with, or ask Iwang. I am no philosopher, myself. But I think it proves the change in colour is not just a matter of bending in itself. I think it shows sunlight, white light if you will, or full light, or simply sunlight, is composed of all the individual colours travelling together.”
The witnesses nodded. Khalid ordered the room opened up, and they retired blinking into the sun to have coffee and cakes.
“This is wonderful,” Zahhar, one of Sher Dor’s senior mathematicians said, “very illuminating, so to speak. But what does it tell us about light, do you think? What is light?”
Khalid shrugged. “God knows, but not men. I think only that we have clarified (so to speak) some of light’s behaviour. And that behaviour has a geometrical aspect. It seems regulated by number, you see. As do so many things in this world. Allah appears to like mathematics, as you yourself have often said, Zahhar. As for the substance of light, what a mystery! It moves quickly, how quickly we do not know; it would be good to find out. And it is hot, as we know by the sun. And it will cross a void, if indeed there is any such thing as a void in this world, in a way that sound will not. it could be that the Hindus are right and there is another element besides earth, fire, air and water, an ether so fine we do not see it, that fills the universe to a plenum and is the medium of movement. Perhaps little corpuscles, bouncing off whatever they strike, as in a mirror, but usually less directly. Depending on what it strikes, a particular colour band is reflected into the eye. Perhaps.” He shrugged. “It is a mystery.”
The Madressas Weigh In
The colour demonstrations caused a great deal of discussion and debate in the madressas, and Khalid learned during this period never to speak of causes in any opinionated way, or to impinge on the realm of the madressa scholars by speaking of Allah’s will, or any other aspect of the nature of reality. He would only say, “Allah gave us our intelligence to better understand the glory of his work,” or, “the world often works mathematically. Allah loves numbers, and mosquitos in springtime, and beauty.”
The scholars went away amused, or irritated, but in any case in a ferment of philosophy. The madressas of Registan Square and elsewhere in the city, and out at Ulug Bek’s old observatory, were buzzing with the new fashion of making demonstrations of various physical phenomena, and Khalid’s was not the only mechanical workshop that could build an ever more complex array of new machines and devices. The mathematicians of Sher Dor Madressa, for instance, interested everyone with a surprising new mercury scale, simple to construct — a bowl containing a pool of mercury, with a narrow tube of mercury, scaled at the top but not the bottom, set upright in the liquid in the bowl. The mercury in the tube dropped a certain distance, creating another mysterious void in the gap left at the top of the tube; but the remainder of the tube stayed filled with a column of mercury. The Sher Dor mathematicians asserted that it was the weight of the world’s air on the mercury in the bowl that pushed down on it enough to keep the mercury in the cylinder from falling all the way down into the bowl. Others maintained it was the disinclination of the void in the top of the tube to grow. Following a suggestion of Iwang’s, they took their device to the top of Snow Mountain, in the Zeravshan Range, and all there saw that the level of mercury in the tube had dropped, presumably because there was less weight of air on it up there, two or three thousand hands higher than the city. This was a great support for Khalid’s previous contention that air weighed on them, and a refutation of Aristotle, and al-Farabi and the rest of the Aristotelian Arabs, who claimed that the four elements want to be in their proper places, high or low. This claim Khalid ridiculed, at least in private. “As if stones or the wind could want to be some place or other, as a man does. It’s really nothing but circular definition again. “Things fall because they want to fall”, as if they could want. Things fall because they fall, that’s all it means. Which is fine, no one knows why things fall, certainly not me, it is a very great mystery. All the seeming cases of action at a distance are a mystery. But first we must say so, we must distinguish the mysteries as mysteries, and proceed from there, demonstrating what happens, and then seeing if that leads us to any thoughts concerning the how or the why.”
The sufi scholars were still inclined to extrapolate from any given demonstration to the ultimate nature of the cosmos, while the mathematically inclined were fascinated by the purely numerical aspects of the results, the geometry of the world as it was revealed. These and other approaches combined in a burst of activity, consisting of demonstrations and talk, and private work on slates over mathematical formulations, and artisanal labour on new or improved devices. On some days it seemed to Bahram that these investigations had filled all Samarqand: Khalid’s compound and the others, the madressas, the ribat, the bazaars, the coffee stalls, the caravanserai, where the traders would take the news out to all the world . . . it was beautiful.
The Chest of Wisdom
Out beyond the western wall of the city, where the old Silk Road ran towards Bokhara, the Armenians were quiet in their little caravanserai, tucked beside the large and raucous Hindu one. The Armenians were cooking in the dusk over their braziers. Their women were bare-headed and bold-eyed, laughing among themselves in their own language. Armenians were good traders, and yet reclusive for all that. They trafficked only in the most expensive goods, and
knew everything about everywhere, it seemed. Of all the trading peoples, they were the most rich and powerful. Unlike the Jews and Nestorians and Zott, they had a little homeland in the Caucasus to which most of them regularly returned, and they were Muslim, most of them, which gave them a tremendous advantage across Dar al-Islam — which was to say all the world, except for China, and India below the Deccan. Rumours that they only pretended to be Muslim, and were secretly Christians all the while, struck Bahram as envious backstabbing by other traders, probably the tricky Zott, who had been cast out of India long before (some said Egypt), and now wandered the world homeless, and did not like the Armenians’ inside position in so many of the most lucrative markets and products.
Bahram wandered among their fires and lamplight, stopping to chat and accept a swallow of wine with familiars of his, until an old man pointed out the bookseller Mantuni, even older, a wizened hunchbacked little man who wore spectacles that made his eyes appear the size of lemons. His Turkic was basic and heavily accented, and Bahram switched to Persian, which Mantuni acknowledged with a grateful dip of the head. The old man indicated a wooden box on the ground, filled entirely with books he had obtained for Khalid in Frengistan. “Will you be able to carry it?” he asked Bahram anxiously.
“Sure,” Bahram said, but he had his own worry: “How much is this going to cost?”
“Oh no, it’s already paid for. Khalid sent me off with the funds, otherwise I would not have been able to afford to buy these. They’re from an estate sale in Damascus, a very old alchemical family that came to an end with a hermit who had no issue. See here, Zosimos’ ‘Treatise on Instruments and Furnaces’, printed just two years ago, that’s for you. I’ve got the rest arranged chronologically by date of composition, as you can see, here is Jabir’s ‘Sum of perfection’, and his ‘Ten Books of Rectification’, and look, ‘The Secret of Creation’.”
This was a huge sheepskin-bound volume. “Written by the Greek Apollonius. One of its chapters is the fabled ‘Emerald Table’,” tapping its cover delicately. “That chapter alone is worth twice what I paid for this whole collection, but they didn’t know. The original of ‘The Emerald Table’ was found by Sara the wife of Abraham, in a cave near Hebron, some time after the Great Flood. It was inscribed on a plate of emerald, which Sara found clasped in the hands of the mummified corpse of Thrice-greatest Hermes, the father of all alchemy. The writing was in Phoenician characters. Although I must admit I have read other accounts that have it discovered by Alexander the Great. In any case here it is, in an Arabic translation from the time of the Baghdad caliphate.”
“Fine,” Bahram said. He wasn’t sure Khalid would still be interested in this stuff.
“You will also find ‘The Complete Biographies of the Immortals’, a rather slender volume, considering, and ‘The Chest of Wisdom’, and a book by a Frengi, Bartholomew the Englishman, ‘On the Properties of Things’, also ‘The Epistle of the Sun to the Crescent Moon’, and ‘The Book of Poisons’, perhaps useful, and ‘The Great Treasure’, and ‘The Document Concerning the Three Similars’, in Chinese —”
“Iwang will be able to read that,” Bahram said. “Thank you.” He tried to pick up the box. It was as if filled with rocks, and he staggered.
“Are you sure you’ll be able to get it back to the city, and safely?”
“I’ll be fine. I’m going to take them to Khalid’s, where Iwang has a room for his work. Thanks again. I’m sure Iwang will want to call on you to talk about these, and perhaps Khalid too. How long will you be in Samarqand?”
“Another month, no more.”
“They’ll be out to talk to you about these.”
Bahram hiked along with the box balanced on his head. He took breaks from time to time to case his head, and fortify himself with more wine. By the time he got back to the compound it was late and his head was swimming, but the lamps were lit in Khalid’s study, and Bahram found the old man in there reading and dropped the box triumphantly before him.
“More to read,” he said, and collapsed on a chair.
The End of Alchemy
Shaking his head at Bahram’s drunkenness, Khalid began going through the box, whistling and chirping. “Same old crap,” he said at one point. Then he pulled one out and opened it. “Ah,” he said, “a Frengi text, translated from Latin to Arabic by an Ibn Rabi of Nsara. Original by one Bartholomew the Englishman, written some time in the sixth century. Let’s see what he has to say, hmm, hmm . . . “ He read with the forefinger of his left hand leading his eyes on a rapid chase over the pages. “What? That’s Ibn Sina direct! . . . And this too!” He looked up at Bahram. “The alchemical sections are taken right out of Ibn Sina!”
He read on, laughed his brief unamused laugh. “Listen to this! ‘Quicksilver’, that’s mercury, “is of so great virtue and strength, that though thou do a stone of an hundred pound weigh upon quicksilver of the weight of two pounds, the quicksilver anon withstandeth the weight.”
“What?”
“Have you ever heard such nonsense? If he was going to speak of measures of weight at all, you’d think he would have the sense to understand them.”
He read on. “Ah,” he said after a while, “Here he quotes Ibn Sina directly. ‘Glass, as Avicenna saith, is among stones as a fool among men, for it taketh all manner of colour and painting.’ Spoken by a very mirrorglass of a man . . . Ha . . . look, here is a story that could be about our Sayyed Abdul Aziz. ‘Long time past, there was one that made glass pliant, which might be amended and wrought with an hammer, and brought a vial made of such glass before Tiberius the Emperor, and threw it down on the ground, and it was not broken, but bent and folded. And he made it right and amended it with a hammer.’ We must demand this glass from Iwang! ‘Then the Emperor commanded to smite off his head anon, lest that this craft were known. For then gold should be no better than clay, and all other metal should be of little worth, for certain if glass vessels were not brittle, they should be accounted of more value than vessels of gold.’ That’s a curious proposition. I suppose glass was rare in his time.” He stood up, stretched, sighed. “Tiberiases, on the other hand, will always be common.”
Most of the other books he paged through quickly and dropped back in the box. He did go through ‘The Emerald Table’ page by page, enlisting Iwang, and later some of the Sher Dor mathematicians, to help him test every sentence in it that contained any tangible suggestion for action in the shops, or out in the world at large. They agreed in the end that it was mostly false information, and that what was true in it was the most trivial of commonplace observations in metallurgy or natural behaviour.
Bahram thought this might be a disappointment to Khalid, but in fact, after all that had passed, he actually seemed pleased at these results, even reassured. Suddenly Bahram understood: Khalid would have been shocked if something magical had occurred, shocked and disappointed, for that would have rendered irregular and unfathomable the very order that he now assumed must exist in nature. So he watched all the tests fail with grim satisfaction, and put the old book containing the wisdom of Hermes Trimestigus high on a shelf with all its brethren, and ignored them from then on. After that it was only his blank books that he cared about, filling them immediately after his demonstrations, and later through the long nights; they lay open everywhere, mostly on the tables and floors of his study. One cold night when Bahram was out for a walk around the compound, he went into Khalid’s study and found the old man asleep on his couch, and he pulled a blanket over him and snuffed most of the lamps, but by the light of the one left burning, he looked at the big books open on the floor. Khalid’s lefthanded writing was jagged to the point of illegibility, a private code, but the little sketched drawings were rather fine in their abrupt way: a crosssection of an eyeball, a big cart, bands of light, cannonball flights, birds’ wings, gearing systems, lists of many varieties of damasked steel, athanor interiors, thermometers, altimeters, clockworks of all kinds, little stick figures fighting with swords or hanging f
rom giant spirals like linden seeds, leering nightmare faces, tigers couchant or rampant, roaring at the scribbles from the margins.
Too cold to look at any more pages, Bahram stared at the sleeping old man, his father-in-law whose brain was so crowded. Strange the people who surround us in this life. He stumbled back to bed and the warmth of Esmerine.
The Speed of Light
The many tests of light in a prism brought back to Khalid the question of how fast it moved, and despite the frequent visits from Nadir or his minions, he could only speak of making a demonstration to determine this speed. Finally he made his arrangements for a test of the matter: they were to divide into two parties, with lanterns in hand, and Khalid’s party would bring along his most accurate timing clock, which now could be stopped instantly with the push of a lever which blocked its movement. A preliminary trial had determined that during the dark of the moon, the biggest lanterns’ light could be seen from the top of Afrasiab Hill to the Shamiana Ridge, across the river valley, about ten li as the crow flies. Using small bonfires blocked and unblocked by rugs would no doubt have extended the maximum distance visible, but Khalid did not think it would be necessary.
They therefore went out at midnight during the next dark of the moon, Bahram with Khalid and Paxkator and several other servants to Afrasiab Hill, Iwang and Jalil and other servants to the Shamiana Ridge. Their lanterns had doors that would drop open in an oiled groove at a speed they had timed, and was as close to an instantaneous reply as they could devise. Khalid’s team would reveal a light and start the clock; when Iwang’s team saw the light, they would open their lantern, and when Khalid’s team saw its light, they would stop the clock. A very straightforward test.
The Years of Rice and Salt Page 27