The southwards pressure was now so great upon him that the normal downwards pull of gravity was virtually negated.

The substance of the mountain was changing beneath him. The hard, almost vertical wall was slowly widening to east and west, slowly flattening, so that behind him the summit of the ridge appeared to be creeping down towards him. He saw a cleft in the rock beside him which was slowly closing, so he removed the grapple from under the spur and thrust it into the cleft. Moments later, the grapple was securely held.

The summit of the ridge had now distended and was beneath his body. The southward pressure took him, and he was swept over the ridge. The rope held and he was suspended horizontally.

What had been the mountain became a hard protuberance beneath his chest, his stomach lay in what had been the valley beyond, his feet scrambled for a hold against the diminishing ridge of what had once been another mountain.

He was flat along the surface of the world, a giant recumbent across an erstwhile mountain region.

He raised his body, trying to ease his position. Lifting his head he suddenly found he was short of breath. A hard, icy wind blew from the north, but it was thin and short of oxygen. He lowered his head again, resting his chin on the ground. At this level his nose could take air that would sustain him.

It was bitterly cold.

There were clouds, and borne on the wind they skimmed a few inches above the ground like a white unbroken sheet. They surged around his face, flowing around his nose like foam at the bow of a ship.

His mouth was below them, his eyes were above.

Helward looked ahead of him through the thin, rarefied atmosphere above the clouds. He looked towards the north.

He was at the edge of the world; its major bulk lay before him.

He could see the whole world.

North of him the ground was level; flat as the top of a table. But at the centre, due north of him, the ground rose from that flatness in a perfectly symmetrical, rising and curving concave spire. It narrowed and narrowed, reaching up, growing ever more slender, rising so high that it was impossible to see where it ended.

He saw it in a multitude of colours. There were broad areas of brown and yellow, patched with green. Further north, there was a blueness: a pure, sapphire blue, bright on the eyes. Over it all, the white of clouds in long, tenuous whorls, in brilliant swarms, in flaky patterns.

The sun was setting. Red to the north-east, it glowed against the impossible horizon.

The shape of it was the same. A broad flat disk that might be an equator; at its centre and to north and south, its poles existed as rising, concave spires.

Helward had seen the sun so often that he no longer questioned its appearance. But now he knew: the world too was that shape.

9

The sun set, and the world became dark.

The southwards pressure was now so great that his body hardly touched what had once been the mountains beneath him. He was hanging on the rope in the darkness, as if vertically against the wall of a cliff; reason told him that he was still horizontal, but reason was in conflict with sensation.

He could no longer trust the strength of the rope. Helward reached forward, curled his fingertips around two small extrusions (had they once been mountains?), and hauled himself forward.

The surface beyond was smoother, and Helward could hardly find a firm hold. With trouble he discovered he could dig his fingers into the ground sufficiently far to obtain a temporary purchase. He dragged himself forward again: a matter of inches… but in another sense a matter of miles. The southwards pressure did not perceptibly diminish.

He abandoned his rope and crawled forward by hand. Another few inches and his feet came into contact with the low ridge that had been the mountain. He pressed hard, moved forward again.

Gradually, the pressure on him began to decrease until it was no longer a matter of desperation to hold on. Helward relaxed for a moment, trying to catch his breath. Even as he did so he felt sure that the pressure was increasing again, so he moved forward. Soon, he had gone so far that he could rest on his hands and knees.

He had not looked south. What had been behind him?

He crawled a long way, then felt able to stand. He did so, leaning northwards to counteract the force. He walked forward, feeling the inexplicable drag steadily diminish. He soon felt he was sufficiently far from the worst zone of pressure to sit on the ground, and take a proper rest.

He looked towards the south. All was darkness. Overhead, the clouds which had broken around his face were now some height above him. They occluded the moon, which Helward, in his untutored way, had never questioned. It too was that strange shape; he had seen it many times, always accepted it.

He continued walking northwards, feeling the immense drag weakening still further. The landscape around him was dark and featureless, and he paid no attention to it. Only one thought dominated his mind: that he must move sufficiently far forward before he rested so that he would not be dragged back again to that zone of pressure. He knew now a basic truth of this world, that the ground was indeed moving as Collings had said. Up north, where the city existed, the ground moved with an almost imperceptible slowness: about one mile in a period of ten days. But further south it moved faster, and its acceleration was exponential. He had seen it in the way the bodies of the girls had changed: in the space of one night the ground had moved sufficiently far for their bodies to be affected by the lateral distortions to which they — and not he — were subjected.

The city could not rest. It was destined to move forever, because if it halted it would start the long slow movement down here — down past — where it would come eventually to the zone where mountains became ridges a few inches high, where an irresistible pressure would sweep it to its destruction.

At that moment, as Helward walked slowly northwards across the strange, dark terrain, he could give no rationale to what he had experienced. Everything conflicted with logic: ground was stable, it could not move. Mountains did not distort as one sprawled across their face. Human beings did not become twelve inches high; chasms did not narrow; babies did not choke on their mothers’ milk.

Though the night was well advanced, Helward felt no tiredness beyond the residue of the physical strain he had endured on the side of the mountain. It occurred to him that the day had passed quickly; faster than he could have credited.

He was well beyond the zone of maximum pressure now, but he was still too aware of it to halt. It was not a pleasant thought to sleep while the ground moved beneath him, bearing him ineluctably southwards.

He was a microcosm of the city: he could no more rest than it.

Tiredness came at last and he sprawled on the hard ground, and slept.

He was awakened by the sunrise, and his first thought was of the southwards pressure. Alarmed, he sprang to his feet and tested his balance: the pressure was there, but not measurably worse than it had been at his last recollection.

He looked towards the south.

There, incredibly, the mountains stood.

It could not be so. He had seen them, felt them reduce to a ridge of hard ground, no more than an inch or two in height. Yet they were clearly there: steep, irregularly shaped, capped with snow.

Helward found his pack, and checked its contents. He had lost the rope and grapple, and much of his equipment had been with the girls when he left them, but he still had one canteen of water, a sleeping-bag, and several packets of the dehydrated food. It would be enough to keep him going for a while.