Strata

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 plastichandle at one end. Kin watched him weigh it thoughtfully in his hand. Ready to take on the makers of a fifteen-thousand mile wide world with a homemade 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 …
    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 sun-warmed 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. Toeither 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 nearby. 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 eight thousand miles from the equator at noon, it was eleven thousand 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