It took several hours to ferry the dumbwaiter across from the lazily spinning ship. At Kin's insistence they also brought the sargo with Jalo in it, and linked it into the emergency system. The waiter had its own internal power supply -- as laid down by regulations. No-one wanted to spend their last hours in a blacked-out ship with any hungry shandi that might be aboard.

The new orbit took them past the disc's moon, no longer shining and obviously invisible in the disc's day sky. They saw that one hemisphere was black.

'Phases,' said Kin. 'Wobble the moon on its axis and you get phases.'

'Who does the wobbling?' asked Marco.

'I don't know. Whoever wanted this thing to look like Earth, from the surface. And don't look at me like that -- I'll swear this wasn't built by humans.'

She spoke to them about artificial worlds -- rings, discs, Dyson spheres and solar tunnels.

'They don't work,' she said. 'That is, they're vulnerable. Too dependent on civilization. And there's too many things to go wrong. Why do you think the Company terraforms worlds when there are cheaper alternatives? Because planets last, that's why. Through anything.

'And I'm certain this wasn't built by Spindles. Planets were important to them. They had to feel the strata below and the unlimited space above. Somehow they could sense it. Living on something like this could drive them out of their skulls. Anyway, they died out four million years ago at least, and I'm positive that this thing isn't that old. It must be all machinery just to keep going, and machines wear out.'

'There's cities down there,' said Marco, 'in the right place, too. If this was Earth.' He looked up. 'OK, Kin, you've been dying to tell us. What did hit us back there ?'

'Was the hole on the ecliptic?'

Marco leaned over and played with the computer terminal for a few seconds. 'Yes,' he said. 'Is it important? The sun was well below us.'

'We were pretty unlucky. I think we were hit by a planet.'

'That was my thought too,' said Silver gravely, 'but I did not like to say anything in case I was thought a fool.'

'Planet?' asked Marco. 'A planet landed on the ship?'

'I know it's usually the other way around, but I think I'm beginning to grasp the workings of this system,' replied Kin. 'There's a fake sky, so there's got to be fake planets. Their orbits must be something to see. If it's really supposed to look like an Earth sky they'd have to be retrograde sometimes.'

'I was wrong,' said Marco. 'We should have started for home. We could have rigged up the sargo and taken turns to wake up. Two thousand years isn't all that long. I don't know what agency told Jalo I was the man for the job, but he's owed his money back.'

'Still, the view's good,' said Kin.

The ship was passing under the disc again. And again there was the flash of green fire as, for a few seconds, the sun shone through the waterfall around the disc.

Something hit them -- again.

It wasn't a planet. It was a ship, and most of it was still hanging in the rearward aerial array when Marco had fought the spin it gave them.

Kin went out this time, and she steadied herself on an aerial stump as she looked at the frosted wreckage.

'Marco?'

'I hear you.'

'It's made one hell of a mess of the antennae.'

'I have already deduced that. We are also losing air. Can you see the leak?'

'There's fog damn near everywhere: I'm going to take a look.'

They heard her boots clump around the hull, and then there was a silence so long that Marco shouted into the radio. When Kin spoke, she spoke slowly.

'It is a ship, Marco. No, wrong word. A boat. A sailing boat. You know, like on seas.'

She looked across at the fire-rimmed disc.

A waterfall pouring over the edge of the world.

The mast was broken and most of the planking had been whirled away by the force of the impact, but enough rope had held together to make it obvious the boat had a passenger.

'Marco?'

'Kin?'

'It had a passenger.'

'Humanoid?'

Kin growled. 'Look, it went over the waterfall and then into vacuum and then hit the ship! What sort of description do you want? It looks like an explosion in a morgue!'

Kin was used to violent death. Oldsters died that way -- freefall diving without a backpack on, deliberately wandering near when they released the cloned elephants on a new world, banjaxing the safeties and stepping into the hopper of a strata machine -- but then ambulance crews took over. There had never been anything to see, except in the strata machine case. And that was only a strange pattern in a freshly laid coal measure.

She knelt like a robot. Wet cloth had frozen in vacuum, but it had been good cloth, well woven. Inside...

Silver later analysed tissue samples, and announced that the passenger had been human enough to call Kin cousin. She would have been surprised at any other result, without being able to say quite why.

He had sailed over the edge of the world. The thought made her go cold. Everyone knew the world was flat, everyone had always known the world was flat: it was obvious. But there was always someone who would laugh at the old men and voyage into the terrifying seas to prove a different theory. And he had been horribly wrong.

Kin was glad about the argument over the suits.

There were five, two of which were shand size. One of the others seemed to be faulty, and the trio were all sufficiently space-cautious not to trust a suspect suit.

'We must take the dumbwaiter,' said Silver. 'Maybe you and Kin will be able to eat what is down there, but I will be poisoned.'

'Get the machine to dish out a sack of dried food concentrates then,' ordered Marco. 'We need that fourth suit.'

Silver grunted. 'Not as much as we need the machine. It can analyse food. It can supply clothing. If necessary we can live off it.'

'I'm inclined to agree,' said Kin.

'It'll take the lifting power of the entire suit!'

'Would you rather take a laser rifle that won't fire?' said Silver. They glared at each other.

'Let's take it for Silver's sake,' said Kin hurriedly. 'Hunger can be a big problem for shandi.'

Marco shrugged twice. 'Take it then,' he said, and snatched the tool kit from a wall locker. While they manhandled the big machine into the space suit and padded it around with thermoblankets, he took the control chair apart and ended up with a strip of metal trim sharpened to a killing edge and with a plastic handle at one end. Kin watched him weigh it thoughtfully in his hand. Ready to take on the makers of a 15,000 mile wide world with a home-made sword. Was that commendable human spirit or stupid kung bravado?

He turned and saw her watching him.

'This is not to put fear into them,' he said, 'but to take fear out of me. Are we ready?'

He programmed the autopilot to hover for ten minutes a few hundred miles from the waterfall. They took off on the suits' lift belts, Silver towing the spare suit on a length of monofilament Line.

Kin glanced over her shoulder as the ship sped away on a spear of flame and climbed towards a high orbit. Then she turned back to the great wall of water, and the little islands on the very edge. Way around the disc the orbiting sun was sinking.

There were no city lights, anywhere.

In a ragged line they flew towards the tumbling water and the thunder at the edge of the world.

No-one had seen, just before the ship soared away, the now perfectly workable fifth suit tumble from the airlock. It inflated instantly, like an empty balloon.

In the big bubble helmet the raven surveyed the emergency controls carefully. The suits were designed for anything -- they could fly across a star system and land on a world. There were tongue controls.

The raven reached out, pecked gently. The suit surged forward. The raven watched intently, then tried another control...