By the time Nish had gone down, then up the first tree again, he was practically treating it like a footpath. He used the block and tackle to pull the two trees closer, then lashed them together. He constructed a platform by cutting one of the sides out of the basket and tying it to the branches. Now the real job would begin.

It went painfully slowly, for the upper part of the tear curved away from the trunk and he had to lean out just to the point of toppling. At the end of the day he had done less than a third of the sewing.

The job took another two days, at which time the cloth ran out when he still had half a span to go. Nish sewed one of his shirts over the remaining slit. The cloth was heavier than silk, but the balloon had less to lift than before, so he hoped it would suffice.

When all was finished, and sealed with tar, he stood back. The repair did not look strong enough. What if they got up into the air and it tore out? Their escape had been miraculous. It would not happen a second time. Unravelling a length of rope, he reinforced the repair with a network of strands and tarred them down. It would have to do. He had no tar left.

It took another day to cut up enough dry fuel, and then he had to carry every stick up on his back. Nish tied the section back into the basket, roped everything down and wove green twigs together to repair the hole in the floor, should he ever succeed in raising the balloon.

‘Amplimet is gone,’ Ullii said suddenly.

‘What?’

She pointed to the west. ‘It went that way.’

‘Do the lyrinx have it?’

‘I don’t know.’

‘What about Tiaan?’

‘Tiaan too.’

He mulled over that while he worked, but there were too many possibilities and he had no way of distinguishing between them. Finally all was ready. Firing up the brazier, he cut away any branch stubs that would impede their upward progress and helped Ullii into her basket. He was stirring the fire with a stick when three things happened at once.

To the east, in the direction of the great mountain, a yellow cigar-shaped object passed across the sky. It looked like a gourd or squash, though tapered at either end. Underneath hung a smaller, elongated container. Nish squinted at the object, wishing for a spyglass. Was it a lyrinx machine of war, brought here to attack Tirthrax?

Ullii let out a screech that made his hair stand on end. Nish spun around, wondering what had so terrified her. She was not looking that way at all. The seeker was staring towards the base of the tree.

‘Hooks and claws,’ she moaned. ‘Hooks and claws.’ Ullii threw herself into her basket and wrenched the lid closed.

Nish caught an unpleasant reek, like hot rotting meat. What was it? Ullii had said something similar before they’d gone up in the balloon. Was it a predator nearby, or just something she had seen in her mental lattice? Better find out. The brazier would not fill the balloon for hours. Thrusting his battered sword through his belt, Nish began to climb down.

Near the bottom, the decaying reek became stronger, until he began to gag. It did not have the smell of a dead animal; more like a live one that had burrowed through decaying flesh.

Nish went still. The noise sounded like a low, purring growl. The purring bothered him more than the growl. Something began scratching at the bark at the back of the trunk.

Drawing his sword, Nish peered down. He could not see anything. Edging around the tree, he looked again. Still nothing. He lowered himself onto the next branch and ducked his head through the twigs. The beast slid around the tree and stood up on all fours, staring straight at him.

NINE

Tiaan lay on her bed, puzzling about the construct until she drifted to sleep. Perhaps that was why she dreamed of the forbidden book, Nunar’s The Mancer’s Art, which she had found hidden in the manufactory. At the very least, discovery would have meant the end of her career, if not her life, so why had she kept it? Partly for the thrill of the forbidden, though she had never been a rebel. But mostly because the night she had read the thoughts of the great Nunar on the nature of power Tiaan had been touched by something.

The basis of mancery, the Secret Art, was the field. Though artisans were mere craft workers, whenever she plied her trade Tiaan felt kinship with the greatest mancers of the age. But until she’d read Runcible Nunar’s book she had not understood what she was doing. The field was just one of several forces that mancers speculated about, and the weakest of all. No one knew how to use the strong forces, or even if they existed. At least, if anyone had, they had not survived to record it.

Minis had taught her the rudiments of geomancy, the greatest of all the Secret Arts, which drew on the forces that shaped and moved the earth. Tiaan had not understood that either, though the Aachim had implied that their geomancy employed one of the strong forces.

Jerking awake, she dug The Mancer’s Art out of her pack where it had lain, carefully wrapped, for months. It was a small, slim volume written in a fine hand on silky rice paper. Tiaan turned the pages, searching for anything to do with geomancy. She did not find that Art mentioned by name, though late that night when she could barely keep her eyes open, she did discover something else.

The Strong Forces and the General Theory of Power

It is my contention that a node may generate as few as four strong forces, or as many as ten. These forces must be mutually orthogonal, and therefore only three can ever manifest themselves in our familiar world. The remainder must lie in other dimensions and can neither influence our physical environment nor be drawn upon by any refinement of the mancer’s Art about which I am competent to speculate.

There followed a theoretical discussion of the strong forces, written in such abstruse language that Tiaan could make no sense of it. And then she found this:

Though I cannot prove it, I believe that the peril of the strong forces lies in their sheer intensity. The weak field is diffuse, so mancers were able to draw upon it without necessarily hazarding their lives, though those who were unlucky, or greedy, frequently made that sacrifice. Cautious mancers could master their Art from nebulous areas of the field, before drawing upon more concentrated parts.

The strong forces offer no such comfort. Essentially planar rather than three-dimensional, they would contain prodigious amounts of power within the plane but virtually none immediately adjacent. They would also be difficult to sense. Thus, any attempt to draw power from a strong force would almost certainly result in annihilation. No mancer could react quickly enough to control it.

Others have argued that a controller device could be fashioned to overcome this limitation. Not in my understanding of the Art. I believe that such forces are forever beyond the tampering fingers of humanity, and rightly so.

Had the Aachim discovered the answer after all? Tiaan recalled her image of the construct mechanism. Surely its controlling parts were in the wrong arrangement to be sensitive to the strong forces, much less to control them – unless the great Nunar was completely wrong? That was possible. The Mancer’s Art had been written a hundred years ago, before the first controller had been invented.

That night, Tiaan had crystal dreams for the first time since opening the gate. They vanished on waking, as usual. She did not leap out of bed, as she was accustomed to do, but lay with the covers pulled well up, thinking about the problem. The Aachim must have a special way of controlling the construct. Could she read that from the aura?