The dawn came wetly. Kin awoke soaked with dew. So much for thermoblankets.

It had been a long night. The island, at the very lip of the rimfall, was hardly big enough to support a dangerous carnivore, unless it was semi-aquatic. But Marco had pointed out that the disc might abound with semi-aquatic carnivores, and had insisted on mounting guard. Kung could do without sleep for weeks at a time.

Kin wondered whether to tell him about her personal stunner, now carefully hidden in a suit pocket. Feeling like a heel, she decided not to. She had a long struggle with her conscience but she won, she won.

Marco had evidently slept with the coming of the sun. He lay curled bonelessly under a dripping bush. Through the mists, Kin saw Silver sitting on the rock outcrop on the fall side of the island.

Kin scrambled up towards her. The shand grinned and made room for her on the sunwarmed stone.

The view was as though from the point of a wedge. The rocky peak rose out of what looked suspiciously like a small wood of ash and maple. Beyond, the sun glinted off silver-green sea. To either side the fall was a white line of foam seen dimly through mist clouds. Behind...

Silver grabbed her in time.

When Kin regained her balance she moved carefully down the slope to a seat that did not hang so obviously over a drop, and asked, 'Can you really sit there and not worry?'

'What's to worry? You did not fret in the ship when there was only a metre of hull between you and eternity,' said the shand.

'That's different. That's a real drop behind you.'

Silver raised her muzzle and sniffed the air.

'Ice,' she exclaimed. 'I smell ice. Kin, may I give you a lecture on sunshine?'

Kin automatically squinted at the sun. Her memory told her it was asteroid size. But it looked right for Earth. It felt right on her skin.

'Go ahead. Tell me something I don't know.'

'I have noticed pack ice going over the fall. Why should this be? We know the disc has polar islands. Yet there are green lands near by. Consider the distance between the equator and the polar islands. Why are not the north and south extremities frozen solid and the equatorial regions burning?'

Kin leaned her chin on her hands. The shand was talking about the inverse square law. If the sun was 5,000 miles from the equator at noon, it was 11,000 miles from what had to be called the poles.

Well, the path that sun followed couldn't be called an orbit. It moved like a guided spaceship. But that didn't explain the warm air around her. Consider: on most worlds the poles were but a few thousand miles further from the primary than was the equator, yet the temperature was wildly different. On the disc, if one thought of the temperate zone as being effectively Earth-distant from the sun, then the poles were out around Wotan and the equator broiled like Venus.

'Some sort of force lens?' she hazarded. 'I could believe anything. Certainly the sun's path must be changed regularly.'

'I do not understand.'

'To get seasons.'

'Ah... seasons. Yes, humans would require seasons.'

'Silver--'

The shand sniffed again. 'This is good air,' she said.

'Silver, stop dodging. You think we built this.'

'Ah -- the kung and I have discussed the topic, it is true.'

'The hell you have! We'd better get this clear. Humans may be mad, but we're not stupid. As a work of celestial mechanics this disc is about as efficient as a rubber spanner. It must drink power to keep going. For crying out loud, you don't want to hang your descendants' lives on the efficiency of dinky little orbiting suns and fake stars! Why didn't the disc builders orbit it around a real sun? They must have had the power. Instead they came out here to nowhere and built a world according to the ideas of some kind of medieval monk. That's not human.'

'The man on the ship was human.'

Kin had been thinking hard and long about him. Sometimes he came into her thoughts unbidden, in the long sleep hours. She hesitated before replying.

'I... don't know. Maybe the disc builders kidnapped a bunch of humans back in prehistory. Or perhaps there was parallel evolution somewhere...'

She felt angry at herself for her ignorance, and even angrier at the shand for diplomatically not picking at the big holes in her argument. If someone had offered Kin an instant return to the comforts of Earth at that moment, she would have spat. There were too many questions to be answered first.

Out loud: 'Jalo talked about matter transmission. I wonder how they get the water up from the bottom of the fall back into the ocean?'

Marco scrambled up the rocks towards them. A change had come over him since the landing on the disc. On the ship Kin remembered him as being moody, cynical -- now he seemed to vibrate with undirected enthusiasm.

'We must make plans,' he said.

'You have a plan,' Kin corrected.

'It is imperative we contact the masters of the disc,' said Marco, nodding and not appearing to notice her sarcasm.

'You have changed your mind, then.' Silver's voice floated down from the heights. She was standing up, sniffing the air again.

'I face facts, however distasteful. We cannot repair the ship. They will have the capacity to do so, or spacecraft we may hire. jalo got back. Or do you wish to spend your life here?'

'I do not think the disc people can help us,' said Silver. 'We detected no power sources, no energy transmission. We landed unaccosted. These are my secondary reasons for suspecting a lapse into barbarianism.'

'Secondary?' said Kin.

Silver grunted. 'There is a ship approaching,' she said. 'By its lines I do not suspect it is a sports plaything of an advanced race.'

They stared at her, then raced up the crag. Marco beat Kin to the top by a series of long leaps and peered out across the water.

'Where? Where?'

Kin saw a speck on the edge of sight.

'It is a rowing ship, twelve oars to a side,' said Silver, squinting slightly. 'There is a mast and a furled sail. It stinks. The crew stink. On their present course they will pass a mile to the north.'

'Over the falls?' said Kin.

'Surely the disc people have mastered the art of dealing with the waterfall,' said Marco. 'The current does not appear to be strong. There is a weir effect.'

Kin thought of the man in the fallen boat.

'They know they're heading for the falls but they don't know what the falls are,' she said. Silver nodded.

'They stink because they are afraid,' she said. 'They are changing course for this island. There is a man standing in the forward end, looking towards the falls.'

Marco became a blur of action.

'We must prepare,' he hissed. 'Follow me down.' Rocks crashed behind him as he bounded back towards the trees where they had spent the night.

Kin glanced from the shand, standing like a statue, to the boat. Even she could see the figures now. Water gleamed as it cascaded off whirling oars. She even thought she could hear shouts.

'I don't think they will make it,' she said quietly.

'That is so,' said Silver. 'See how the current swings them round.'

'It may be a test,' said Kin. 'I mean, the very day we're here and all.'

Silver sniffed. 'My nose says not.'

They looked at each other. Kin certainly was not going to argue with 350 million smell cells. She could see the men in the boat clearly. There was one, a small, bearded man, racing between the bent rowers and urging them on. At best the boat was standing still.

'Ahem,' suggested Silver.

Kin squinted up at the sun.

'You recall that Line we're using to tow the spare suit?' she said. 'How long is it?'

'Standard monofilament length, fifteen hundred metres,' said Silver, adding, 'It could tether a world.'

'Of course, we could be making a big mistake; said Kin, starting to run down the slope. Silver lumbered after her.