Alchymist

'What is it, Tiaan?' said Malien.

'Just after the earth trembler, the amplimet began to blink, and now something is taking vast amounts of power from the Stassor node. I'm afraid—'

'It's not the amplimet,' said Bilfis. 'My people are building a great defence against attack by thapters or other kinds of flying machines.'

'That's all right then,' said Tiaan. 'Isn't it?'

'We're afraid they'll overload the node, or worse,' said Malien direly. 'If you recall, Tiaan, I mentioned this worry in Tirthrax. But my people won't listen. They're too afraid.'

'Of what?'

Anyone and everyone. Once the secret of flight gets out, and surely that won't take long, Stassor will be vulnerable to attack by a fleet of thapters. Suddenly its isolation will be a disadvantage rather than a protection.'

'I see. And what could be worse than overloading the node?'

'Overloading all the nodes.'

Tiaan looked from one to the other. 'I don't understand.'

'We're not sure we do either,' said Bilfis, 'but we're beginning to think that the nodes might not be separate, as has always been thought, but linked!

Through strong forces that can't be detected,' said Malien. Humanity has already seen the lyrinx drain nodes dry. They normally recover within days of the node-drainer being removed, though we don't understand how that can happen so quickly. It should take years for a node to regenerate the field by itself.'

'Unless,' said Bilfis, 'it's replenished from outside, from other nodes.'

'But that's good, isn't it?' Tiaan searched their faces.

'We thought so, until we heard about the death of the Snizort node' said Bilfis. 'That's bothered me ever since I heard the news. I'm afraid …' He looked to Malien. She nodded.

'Yes?' said Tiaan.

'If the nodes are linked, it could be a problem.'

'What do you mean?'

'Every month humanity adds more clankers to the thousands they're already using, along with a myriad of other devices that draw power from the field. The lyrinx do the same, as does Vithis with his thousands of constructs. Now Stassor has embarked on this city-sized shield and just to build it will take much from the node. Maintaining it day after day, year after year, will require far more. It adds up to too much power, taken too quickly, and there's got to be a consequence. It may drain the node dry and, if the nodes are linked, the ones surrounding it as well. Perhaps even the ones surrounding them. You see the danger?'

'I think so …' said Tiaan.

'If many nodes fail at once, the great forces that create them will ultimately have to readjust. What's that going to do to the puny creatures clinging to Santhenar's fragile shell?'

'Are you saying that some of the nodes might explode, as at Snizort?' asked Tiaan.

'That's one possibility, and the explosive force could spread to the nodes surrounding them,' said Malien. 'Or the driving forces themselves could become unbalanced, tearing the crust of the world apart. No one knows enough geomancy to tell.'

'Is there any way to find out.’

'That's what we've been talking about.'

'Bilfis and I have put our concerns to the Aachim Syndic,' said Malien the following morning. 'That last earth trembler alarmed them, so we turned the screws. My people aren't happy, but they've agreed to give us what we want, in return for the secret of flight. They want to build their own thapters.'

'Is that wise?' said Tiaan, but regretted it as soon as she'd spoken. She had no right to question Malien.

'I had nothing else to bargain with.'

'What are they giving in return?'

'Everything they know about nodes.'

'You might have demanded that by right,' said Bilfis.

'And they might have stalled me for months,' said Malien. This way we can begin in a week.'

'To do what?' said Tiaan.

'To map the nodes near Stassor, so we can see how they're being affected.'

'Can I come too?' Tiaan was used to being busy but there would be nothing for her to do here. 'I'll do anything that needs doing.'

'I want you to come,' said Malien. 'Indeed, I can't do it without you.'

By the time the Aachim had released the thapter and made a start on building their own, weeks later, Tiaan, Malien and a mapmaker had gone through the archives and produced a series of charts of the mountains surrounding Stassor. These showed all nodes the Aachim knew about.

There were many kinds: weak nodes and strong, steady ones and those whose fields fluctuated wildly or unpre-dictably, or flared up only to die away to nothing. There were occasional double nodes and one triple — which Malien was too perilous to approach — as well as two anti-nodes which were even more dangerous. The anti-nodes may have grown by cannibalising the fields of others, but no one had ever dared approach close enough to find out.

Only then did Tiaan and Malien sit down, with a small glass of the Aachim liquor called syspial in hand, and consider their work. The nodes were not evenly distributed but fell into patterns, groups and aggregations, which in turn were organised into provinces. These often corresponded to geographic features like mountain chains, volcanoes, cliffs or ridges. Not always, though — some nodes were not related to anything on the surface of the earth.

Tiaan took a sip of her drink, which was the colour and flavour of sweet blackberry liqueur, but stingingly spicy-hot. 'Where do nodes come from, anyway?'

'No one has any idea,' said Malien, 'except, possibly, your friend Gilhaelith. He knows more about the natural philosophy of the world than anyone.'

'It's been his life's work.' She wondered if Gilhaelith was still alive; and if so, what he was up to.

The next step was to go out at night in the thapter, mapping the fields of the nodes while Malien flew a course by the moon or the stars, and Bilfis plotted the fields on the chart. Tiaan was forced to use the amplimet, which was always risky now. Once or twice she flew the thapter, and had to use the crystal for that as well. She did not have the talent to fly the thapter the way Malien did.

They spent a tedious month on this work, by which time they had created a map of the area within forty leagues of Stassor. It was very rough, but to refine it would have taken months more, for they learned something new every day: new fields and new nodes, even new kinds of nodes. Tiaan wished she understood them.

By that time, two teams, each one comprising hundreds of Aachim, working day and night, had built a pair of thapters, though only the second of them remained at Stassor: the other machine had flown west a fortnight ago. Tiaan suspected it had been sent on an embassy to Vithis, and she was not looking forward to its return.

The following morning she was in the front meeting room when there was a screeching whine outside and the missing thapter shot past a transparent section of wall, heading for the compressed-ice platform.

'Who's that?' Malien said sharply.

'Tormil,' said Harjax. 'I sent him to make contact with Vithis, and from his haste I'd say he has.' He bent his head to his papers.

Malien's left hand gripped Tiaan's knee under the table and squeezed hard — a warning. She wrote a note on a scrap of paper and passed it to Tiaan. 'Would you take this to Bilfis, please? He's in his room.'

'Of course,' said Tiaan. She rose, bowing to the Aachim, who ignored her as usual, and hurried out.

The operator was in such haste that he had flown his thapter right up to the cubular doors, which were spreading apart as Tiaan went by. He threw himself over the side, almost falling in his haste.

Tiaan made her way to Bilfis's room, and found him sitting at the table, poring over his field maps.

'Malien asked me to give you this.' She passed him the paper.

He scanned it, thrust it into his pocket, rolled the maps and sprang up. 'Take these to Malien's thapter. Act normally. Have you your amplimet?'