The Inverted World

1

The valley was dark and silent. Across on the northern side of the river I saw a red light flash on twice, then nothing.

Seconds later, I heard from deep within the city the grinding of the winch-drums, and the city began to inch forward. The sound echoed around the valley.

I was lying with about thirty other men in the tangled undergrowth that spread across the face of the hill. I had been drafted temporarily to work with the Militia during this most critical of all the city’s crossings. The third attack was anticipated at any moment, and it had been judged that once the city could reach the northern bank of the river it would, by nature of the surrounding terrain, be able to defend itself sufficiently long for the tracks to be extended at least as far as the highest point of the pass through the hills to the north. Once there, it was thought that it could again defend itself for the next phase of track-laying.

Somewhere in the valley we knew that there were about a hundred and fifty tooks, all armed with rifles. They presented a formidable enemy. The city had only twelve rifles taken from the tooks, and the ammunition for them had been spent during the second attack. Our only realistic weapons were the crossbows — at short range, deadly — and an awareness of the value of intelligence work. It was this latter which had enabled us to prepare the reserve counter-attack of which I was a part.

A few hours earlier, as darkness fell, we had taken up this position overlooking the valley. The main force of defence was three ranks of crossbowmen deployed around the city itself. As the city started out across the bridge they would retreat, until they formed a defensive position around the tracks. The tooks would concentrate their fire on these men, and at that moment we could spring our ambush.

With fortune on our side, the counter-attack would not be necessary. Though intelligence work had established that another attack was likely, the bridge-building work had been completed faster than anticipated, and it was hoped that the city would be safely across to the other side under cover of darkness before the tooks realized.

But in the still of the valley, the sound of the winches was unmistakable.

The forward edge of the city had just reached the bridge itself when the first shots were heard. I placed a bolt in the bow, and held my hand over the safety-catch.

It was a cloudy night, and visibility was poor. I had seen the flashes from the rifles, and estimated that the tooks were ranged in a rough semi-circle, approximately one hundred yards from our men. I could not tell if any of their bullets had hit, but so far there were no answering shots.

More rifles fired, and we could tell the tooks were closing in. The city had half its bulk on the bridge… and still crept forward.

Down below, a distant shout: “Lights!”

Instantly, a battery of eight arc-lamps situated on the rear of the city came on, directed over the heads of the crossbowmen and into the surrounding terrain. The tooks were there, not taking any kind of cover.

The first rank of crossbowmen loosed their bolts, hunched down, and started to reload. The second rank shot, hunched down, and reloaded. The third rank shot, reloaded.

Taken by surprise the tooks had suffered several casualties, but now they threw themselves down against the ground and fired at all they could see of the defenders: the black silhouettes against the arc-lamps.

“Lights off!”

Darkness fell at once, and the crossbowmen by the city dispersed. A few seconds later the lights came on again, and the crossbowmen fired from their new positions.

Once again the tooks were taken off aim, and more casualties were inflicted. The lights went off again, and in the sudden darkness the crossbowmen returned to their former position. The manoeuvre was repeated.

There was a shout from below, and as the arc-lamps came on we saw that the tooks were charging. The city was now on the bridge.

Suddenly, there was a loud explosion and a gush of flame against the side of the city. An instant later a second explosion occurred on the bridge itself, and flames spread across the dry timber of the rail-way.

“Reserve force, ready!” I stood up, and waited for the order. I was no longer frightened, and the tension of the waiting hours had disappeared. “Advance!”

The arc-lamps on the city were still burning, and we could see the tooks clearly. Most of them were engaged in a hand-to-hand battle with the main defence, but several more were crouched on the ground, taking careful aim at the superstructure of the city. Two of the arc-lamps were hit, and they went out.

The flames on the bridge and against the side of the city were spreading.

I saw a took near the bank of the river, swinging his arm back in preparation to throw a metal cylinder. I was no more than twenty yards from him. I aimed, released the bolt… and hit the man in his chest. The incendiary bomb fell a few yards away from him, and exploded in a burst of heat and flame.

Our counter-attack had, as anticipated, taken the enemy by surprise. We managed to hit three more of the men… but suddenly they broke off and ran towards the east, disappearing into the shadows of the valley.

There was considerable confusion for a minute or two. The city was on fire, and beneath it the bridge was burning fiercely in two separate places. One concentration of flame was directly beneath the city, but the other was a few yards behind it. It was obviously urgent to deal with the fires, but no one was certain that all the tooks had retreated.

The city continued to winch forward, but where the bridge burned large sections of timber were falling away into the river.

Order was restored quickly. A Militia officer shouted orders, and the men formed into two groups. One group renewed the defensive position around the tracks; I joined the second group sent out on to the bridge to fight the fire.

After the second attack — in which incendiaries had been used for the first time — fire-points had been fitted to the outside of the city. The nearest of these had been damaged in one of the explosions, and water was gushing away from it uselessly. We found a second one, and unravelled the short length of hose.

The intensity of the track-fire was too great, and it was almost hopeless to try to fight it. Although the city had now passed over the worst of the damage there were still three of the main runner-wheels to roll over the burning timber… and as we fought in the dense smoke and billowing flames I saw the rail beginning to twist under the combined forces of heat and weight.

There was a roar, and another section of timber fell away. The smoke was too thick. Choking, we had to back out from under the city.

The fire in the superstructure was still blazing, but a fire-crew inside the city was attempting to deal with it. The winches turned… the city crept slowly towards the comparative safety of the northern bank.

2

In the morning light the damage was assessed. In terms of lost human life, the city had not fared too badly. Three of the militiamen had been killed in the shooting, and fifteen had been injured. Inside the city, one man had been seriously wounded in one of the incendiary explosions, and a dozen more men and women had been overcome by smoke in the ensuing fires.

The physical damage to the city itself was extensive. A whole section of administrative offices had been gutted by the fire, and some of the accommodation section was uninhabitable because of fire or water damage.

Beneath the city there was more damage. Although the main base of the city was steel, much of the construction was timber, and there were whole sections which had been burnt out. The rear ruiiner-wheels on the right outer track had been derailed, and one of the great wheels had sustained a structural crack. It could not be replaced: it would have to be discarded.

After the city had reached the northern bank, the bridge had continued to burn and was now a total loss. With it had gone several hundred yards of our irreplaceable rails, warped and twisted by the heat.

After two days outside the city, working with the track-crews who were salvaging what there was of the rails on the southern bank of the river, I was summoned to see Clausewitz.

Apart from an hour or two spent inside the city when I first returned, I had not reported formally to any of my senior guildsmen. As far as I could determine, the normal protocol of the guilds had been abandoned for the duration of the emergency, and as I myself could see no end to the serious situation — the attacks had caused inevitable delays, and the optimum was ever further away — I had not expected anyone to call me off my work outside.

There was a disturbing mood amongst those men who were outside — half-way between despair and desperation. The work continued on laying the tracks towards the pass, but the relaxed energy of my early days outside the city seemed to be a long way behind us. Now the tracks were being built in spite of the situation with the tooks, rather than in the way I now understood the motivation of the city to be derived, from an internal need to survive in a strange environment.

The talk among the track-crews, the Militia, the Traction men was all centred in one way or another around the attacks. No longer was there talk of gaining ground on the optimum, or what dangers lay down past. The city was in a crisis, and this was reflected in everyone’s attitude.

When I went inside the city the change was apparent here too.

Gone was the light, aseptic appearance of the corridors, gone was the general atmosphere of workaday routines.

The elevator was no longer working. Many of the main doors in the corridors were locked, and at one point an entire wall had been torn away — presumably as a result of one of the fires — so that anyone walking through that part of the city could see what was outside. I remembered Victoria’s frustrations of old, and reflected that whatever secrecy the guilds might have tried to maintain in the past, no longer was such a system possible.

Thought of Victoria pained me; I still did not realize fully what had happened. In what seemed to me to be the passage of a few days, she had abandoned all the tacit understandings of the marriage between us, and gone to pursue another life without me.

I had not seen her since my return, though I had made sure that she would have known I was back in the city. Under the conditions of the external threat it had not been possible to see her anyway, but that aspect of my life was one I needed time to consider before meeting her. The news of her pregnancy by another man — I was told he was an education administrator named Yung — had not hit me too hard at first, simply because I had just not believed it. Such a situation could not possibly have developed in the time I knew I had been away from the city.

I found my way to the first-order guild area with some difficulty. The interior of the city had changed in many ways.

There seemed to be people, noise, and dirt everywhere. Every spare yard of space had been given over to emergency sleeping-room, and even in some of the corridors lay wounded men from outside. Several walls and partitions had been taken down, and just outside the first-order quarters — where there had been a series of pleasantly appointed recreation rooms for the guildsmen — an emergency kitchen had been placed.

The smell of burnt wood was everywhere.

I knew a fundamental change was coming over the city. I could feel the old structure of the guilds crumbling away. The roles of many people had already changed; working with the track-crews I’d met several men for whom it was the first time outside the city, men who until the attacks had worked on food synthesis, or education, or domestic administration. Took labour was now obviously impossible, and all hands had to be called to move the city. Why at this moment Clausewitz had summoned me I could not imagine.

There was no sign of him in the Futures’ room, and so I waited for a while. After half an hour he had still not appeared, so knowing my services could be better employed outside I headed back the way I had come.

I met Future Denton in the corridor.

“You’re Future Mann, aren’t you?”

“Yes.”

“We’re leaving the city. Are you ready now?”

“I was supposed to be seeing Future Clausewitz.”

“That’s right. He’s sent me instead. Can you ride a horse?”

I had forgotten the horses while I was away from the city. “Yes.”

“Good. Meet me at the stables in an hour’s time.”

He walked on into the Futures’ room.

With an hour to spend on my own, I realized that I had nothing to do, no one to see. All my connections with the city were broken; even associative memories of the physical shape and appearance of the city had been disrupted by the damage.

I walked down to the rear of the city to see for myself the extent of the damage to the crèche, but there was not much to see. Almost the whole superstructure had been burnt or latterly demolished, and where the children had been housed was merely the bare steel of the main base of the city. From there I could see back across the river to where the attack had taken place. I wondered whether the tooks would try again. I felt they had been well beaten, but if the city was resented as much as appeared I supposed they would eventually re-form and attack once more.

It came home to me just how vulnerable the city was. Not designed to repel any kind of attack, it was slow-moving, ungainly, built of highly inflammable materials. All its weakest points, the tracks, the cables, the timber superstructure, were easily accessible.

I wondered if the tooks realized how easy it would be to destroy the city: all they needed to do was disable its motive powers permanently, then sit back and watch as the movement of the ground slowly bore it southwards.

I considered this for some time. It seemed to me that the local people did not understand the inherent frailty of the city and its inhabitants, because of the lack of information available to them. As far as I could tell, the strange transformation that had overtaken the three girls down past was subjectively to them no transformation at all.

Here, near optimum, the tooks were not subject to distortion — or only to an indiscernible degree — and so no perception of any difference was possible.

Only if the tooks succeeded, perhaps not even by design, in delaying the city to such a degree that it was borne to a point so far south that it could never haul itself forward again would they see the effect this would have on the city and its occupants.

Under normal conditions, the city would be facing difficult country; the hill to the north of us was probably not the only one in this region. How could it ever again hope to approach the optimum?

For the moment, though, the city was relatively secure. Bounded on one side by the river, and by rising ground which would afford no cover to any aggressor on the other, it was strategically well placed while the tracks were laid.

I wondered whether I had time to find a change of clothes, as I had been working and sleeping in the same ones for many days. This thought inevitably reminded me of Victoria, and how she had objected to my uniform after ten days in it outside the city.

I hoped I should not see her before I left.

I returned to the Futures’ room, and made enquiries. There were indeed uniforms available, and I was entitled to one as I was now a full guildsman… but there was none available at the moment. I was told that one would be found while I was away.

Future Denton was waiting for me when I arrived at the stables. I was given a horse, and without further delay we rode out from beneath the city and headed north.

3

Denton was not a man who would say much unprompted. He answered any questions I chose to ask, but between there were long periods of silence. I did not find this uncomfortable, because it gave me a much needed opportunity to think.

The early training of the guilds still ran true: I accepted that I would make what I could of what I saw, and not rely on the interpretations of others.

We followed the proposed line of the tracks, up around the side of the hill and through the pass. At the top, the ground ran steadily downwards for a long way, following a small watercourse. There was a small patch of woodland at the end of the valley, and then another line of hills.

“Denton, why have we left the city at this moment?” I said. “Surely every man is needed.”

“Our work is always important.”

“More important than defending the city?”

“Yes.”

As we rode he explained that during the last few miles the future-surveying work had been neglected. This was partly because of the troubles, and partly because the guild was undermanned.

“We’ve surveyed as far as these hills,” he said. “Those trees… they’re a nuisance to the Track guild, and they could provide cover for the tooks, but we need more timber. The hills have been surveyed for about another mile, but beyond that it’s all virgin territory.”

He showed me a map that had been drawn on a long roll of paper, and explained the symbols to me. Our job, as far as I could tell, was to extend the map northwards. Denton had a surveying instrument mounted on a large wooden tripod, and every so often he would take a reading from it and make inscriptions on the map.

The horses were heavily laden with equipment. In addition to large supplies of food and bedding, we were each carrying a crossbow and a good supply of bolts; there was some digging equipment, a chemical-sampling kit, and a miniature video camera and recording equipment. I was given the video kit to use, and Denton showed me how to operate it.

The usual method of the Futures, as he explained it to me, was that over a period of time a different surveyor, or a different team of surveyors, would move north of the city by different routes. By the end of the expedition he would have a detailed map of the terrain through which he had passed, and a video record of its physical appearance. This would then be submitted to the Council of Navigators and they, with the help of other surveyors’ reports, would decide which route would be taken.

Towards late afternoon, Denton stopped for about the sixth time and erected his tripod. After he had taken angular readings on the elevation of the surrounding hills, and, by use of a gyroscopically mounted compass, had determined true north, he attached a free-swinging pendulum to the base of the instrument. The weight of the pendulum was pointed, and when its natural momentum was spent and the pointer was stationary, Denton took a graduated scale, marked with concentric circles, and placed it between the legs of the tripod.

The pointer was almost exactly above the central mark.

“We’re at optimum,” he said. “Know what that means?”

“Not exactly.”

“You’ve been down past, haven’t you?” I confirmed this. “There’s always centrifugal force to contend with on this world. The further south one travels, the greater that force is. It’s always present anywhere south of optimum, but it makes no practicable difference to normal operations for about twelve miles south of optimum. Anything further than that, and the city would have real problems. You know that anyway, if you’ve felt the centrifugal force.”

He took further readings from his instrument.

“Eight and a half miles,” he said. “That’s the distance between here and the city… or how much ground the city has to make up.”

I said: “How is the optimum measured?”

“By its null gravitational distortions. It serves as the standard by which we measure the city’s progress. In physical terms, imagine it as a line drawn around the world.”

“And the optimum is always moving?”

“No. The optimum is stationary… but the ground moves away from it.”

“Oh yes.”

We packed our gear and continued northwards. Just before sunset we made camp for the night.

4

The surveying work was undemanding mentally, and as we moved slowly northwards I found that my only external preoccupation was a need to be ever-watchful for signs of hostile inhabitants. Denton told me that an attack on us was unlikely, but nevertheless we were on our guard.

I was still thinking about the awesome experience of seeing the whole world lying before me. As an event, it was enough; understanding it was something else.

On our third day out from the city I suddenly started to think about the education I had been given as a child. I’m not sure what started the train of thought; it was possibly a number of things, not least the shock of seeing how utterly the crèche had been destroyed.

I had thought little of my education since leaving the crèche. At the time I had felt, in common with most of the children in the crèche, that the teaching we were given was not much more than a penance, in which time was served as of necessity. But looking back, much of the education pushed into our unwilling heads took on a new dimension in the context of the city.

For instance, one of the subjects which had inspired in us the most boredom was what the teachers referred to as “geography.” Most of these lessons had been concerned with the techniques of cartography and surveying; in the enclosed environment of the crèche, such exercises had been almost wholly theoretical. Now, though, those hours of tedium took on their relevance at long last. With a little concentration and a certain amount of digging into my often faulty memory, I grasped quickly the principles of the work Denton was showing me.

We had had many other subjects taught to us theoretically, and I saw now how those too had practical relevance. Any new guild apprentice would already have a background knowledge of the work his own guild would expect him to do, and in addition would have similar information about many of the other functions of the city.

Nothing could have prepared me for the sheer physical grind of working on the tracks, but I’d had an almost instinctive understanding of the actual machinery used to haul the city along those tracks.

I cared not at all for the compulsory training with the Militia, but the puzzling — at the time — emphasis placed on military strategy during our education would clearly help those men who later took arms for the security of the city.

This process of thought led me to wonder whether there had been anything in my education that could possibly have prepared me for the sight of a world which was shaped the way this one appeared to be.

The lessons we had been given which specifically referred to astrophysics and astronomy had always spoken of planets as spheres. Earth — the planet, not our city — was described as an oblate spheroid, and we had been shown maps of some of its land surface area. This aspect of physical science was not dwelt upon; I’d grown up to assume that the world on which Earth city existed was a sphere like Earth planet, and nothing I had been taught had contradicted this assumption. Indeed, the nature of the world was never discussed openly at all.

I knew that Earth planet was part of a system of planets, which were orbiting a spherical sun. Earth planet itself was circled by a spherical satellite. Again, this information seemed always to be theoretical… and this lack of practical application had not concerned me even when I left the city, for it was always clear that a different circumstance obtained. The sun and moon were not spherical, and neither was the world on which we lived.

The question remained: where were we?

The solution lay perhaps in the past.

This too had been covered comprehensively, although the histories we were taught were exclusively about Earth planet. Much of what we learned concerned military manoeuvres, the transference of power and government from one state to another. We knew that time was measured in terms of years and centuries on Earth planet, that recorded history existed for about twenty centuries. Perhaps unfairly, I formed an impression that I should not care to live on Earth planet, as most of its existence seemed to be a series of disputes, wars, ter1itorial claims, economic pressures. The concept of civilization was far advanced, and explained to us as the state in which mankind congregated within cities. By definition, we of Earth city were civilized, but there seemed to be no resemblance between our existence and theirs. Civilization on Earth planet was equated with selfishness and greed; those people who lived in a civilized state exploited those who did not. There were shortages of vital commodities on Earth planet, and the people in the civilized nations were able to monopolize those commodities by reason of their greater economic strength. This imbalance appeared to be at the root of the disputes.

I suddenly saw parallels between our civilization and theirs. The city was undoubtedly on a war footing as a result of the situation with the tooks, and that in its turn was a product of our barter system. We did not exploit them through wealth, but we had a surplus of the commodities in short supply on Earth planet: food, fuel energy, raw materials. Our shortage was manpower, and we paid for that with our surplus commodities.

The process was inverted, but the product was the same.

Following my line of reasoning, I saw that the examination of the history of Earth planet prepared the way for those who would become Barter guildsmen, but it took me no further along my own search for understanding. The histories began and ended on Earth planet, with no mention of how the city came to be on this world, nor how the city had been built, nor about who its founders were and where they came from.

A deliberate omission? Or forgotten knowledge?

I imagined that many guildsmen had tried to construct their own patterns of logic, and for all I knew either the answers were available somewhere in the city, or there was a commonly accepted hypothesis which I had not yet encountered. But I had fallen naturally into the ways of the guildsmen. Survival on this world was a matter of initiative: on the grand scale, by hauling the city northwards away from that zone of amazing distortion behind us, and on the personal scale by deriving for oneself a pattern of life that was self-determined. Future Denton was a self-sufficient man, and so had been most of those I had met. I wanted to be one with them, and comprehend things on my own account. I supposed that I could discuss my thoughts with Denton, but I chose not to.

The journey northwards was slow and meandering. We did not take a route due north, but followed many diversions to east and west. Periodically Denton would measure our position against optimum, and never at any time were we further north than about fifteen miles.

I asked him if there were any reason why we should not strike even further north of optimum.

“Normally, we would go as far north as we can,” he said. “But the city’s in a special circumstance. As well as seeking the easiest northwards route, we need terrain that will allow us to defend ourselves best.”

The map we were compiling was becoming more complete and detailed every day. Denton allowed me to operate the equipment whenever I wished, and soon I was as adept as he. I learned how to triangulate the land with the surveying instrument, how to estimate the elevation of hills, and how to calculate the distance we were north or south of optimum. I was growing to like working the camera, in spite of the fact I was forced to curb my enthusiasm to conserve the energy in the batteries.

It was peaceful and agreeable away from the tensions of the city, and I discovered that Denton, in spite of his long silences, was an amiable and intelligent man.

I had lost track of the days we had been away, but it was certainly at least twenty. Denton showed no sign of wanting to return.

We encountered a small settlement, nestling in a shallow valley. We made no attempt to approach it. Denton merely marked it on the map, with a rough estimate of the population.

The countryside was greener and fresher than that to which I had grown accustomed, although the sun was no cooler. It rained more often here, usually during the night, and there were many different sizes of streams and rivers.

All the features of the region, natural or man-made, difficult for the city to pass through or suitable to its peculiar needs, Denton marked without comment on his map. It was not the job of the Future Surveyors to decide which route the city should take; we worked simply to establish the actual nature of future terrain.

The atmosphere was restful and soporific, the natural beauty of our surroundings seductive. I knew the city would travel through this region in the miles to come, and pass it without registering appreciation. For the city’s aesthetics, this verdant and gentle countryside might equally be a windswept desert.

During the hours when I was not actually engaged in any of our routine tasks, I was still lost in speculative thought. I could not get out of my mind that spectacle of the manifest appearance of the world on which we existed. There must have been something, somewhere in those long years of tedious education that would, subconsciously, have prepared me for that sight. We live by our assumptions; if one took for granted that the world we travelled across was like any other, could any education ever prepare one for a total reversal of that assumption?

The preparation for that sight had begun the day Future Denton had taken me outside the city for the first time, to see for myself a sun that revealed itself to be any shape but that of a sphere.

But I still felt there must have been an earlier clue.

I waited for a few more days, still worrying at the problem when I found time, then had an idea. Denton and I had camped one evening in open country beside a broad, shallow river, and as sunset approached I took the video camera and recorder and walked alone up the side of a low hill about half a mile away. At the top there was a clear view towards the north-eastern horizon.

As the sun neared the horizon, the atmospheric haze dimmed its glare and its shape became visible: as ever, a broad disk spiked top and bottom. I switched on the camera, and took a long shot of it. Later I replayed the tape, checking that the picture was clear and steady.

I never tired of the spectacle. The sky was reddening, and after the main disk had passed beneath the horizon, the upright pinnacle of light slid quickly down. For a few minutes after its passing there was an impression of a bright focus of orangewhite at the centre of the red glow… but soon this passed and night came on quickly.

I played the tape again, watching the image of the sun on the recorder’s tiny monitor. I froze the picture, then adjusted the brightness control, dimming the image until only the white shape remained.

There in miniature was an image of the world. My world. I had seen that shape before… long before leaving the confines of the crèche. Those weird symmetrical curves made an overall pattern that someone had once shown me.

I stared at the monitor screen for a long time, then conscience struck me and I switched off to conserve the batteries. I did not return to Denton straight away: I was straining my memory for some key to that faint recollection of the time when someone had drawn four lines on a sheet of card, and held up for all to see the place where Earth city struggled to survive.

The map that Denton and I were compiling was taking on a definite shape.

Drawn on the long roll of stiff paper he had brought, the plan took the form of a long, narrow funnel, with its narrowest point at the patch of woodland a mile or so to the north of where the city had been when we left it. Our travels had all been within the funnel, enabling us to make measurements of large features from all sides, to ensure that we compiled information as nearly accurate as possible.

Soon the work was finished, and Denton said that we would return at once to the city.

I had, in the video recorder, a complete and cross-referenced visual record of all the terrain we had covered. In the city, the Council of Navigators would examine as much as they felt necessary to plan the city’s next route. Denton told me that other Futures would go north soon, draw another funnel map of the terrain. Perhaps it too would start at the patch of woodland, and take a course five or ten degrees to east or west, or, if the Navigators felt that a safe route could be found in the terrain we had surveyed, the new map would start further up the known territory, and push forward again the frontier of the future we had surveyed.

We headed back towards the city. I had expected, in some melodramatic way, that now we had the information we had been despatched to obtain, we would ride through day and night with no regard to safety or comfort; instead, the leisurely ride through the countryside continued.

“Shouldn’t we hurry?” I said in the end, thinking that perhaps Denton was idling for some reason connected with me; I wished to show that I was willing to move with speed.

“There’s never any hurry up future,” he said.

I didn’t argue with him, but it had occurred to me that we had been away from the city for at least thirty days. In that time, the movement of the ground would have taken the city another three miles away from the optimum, and consequently the city would have had to travel at least that distance to stay within safety limits.

I knew that the unsurveyed territory began only a mile or so beyond the city’s last position.

In short, the city would need the information we had.

The return journey took three days. On the third day, as we loaded the horses and continued on south, the memory I had been seeking came to me. It came unbidden, as is often the case when trying for something buried in the subconscious.

I felt I had exhausted all my conscious memories of the lessons I’d had, and sorting through the memory of the long academic courses had been as fruitless as the sessions had been tedious at the time.

Then, from a subject I had not even considered, the answer came.

I remembered a period in my last few miles inside the crèche, when our teacher had taken us into the realms of calculus. All aspects of mathematics had induced the same response in me — I showed neither interest nor success — and this further development of abstract concepts had seemed no different.

The teaching had covered a kind of calculus known as functions, and we were taught how to draw graphs representing these functions. It was the graphs that had provided the memory key: I had always had a moderate talent for drawing, and for a few days my interest had flickered into life. It died almost immediately, for I discovered that the graphs were not an end in themselves but were drawn to provide a means of finding out more about the function… and I didn’t know what a function was.

One graph in particular had been discussed in great and onerous detail.

It showed the curve of an equation where one value was represented as a reciprocal — or an inverse — of the other. The graph for this was a hyperbola. One part of the graph was drawn in the positive quadrant, one in the negative. Each end of the curve had an infinite value, both positive and negative.

The teacher had discussed what would happen if that graph were to be rotated about one of its axes. I had neither understood why graphs should be drawn, nor that one might rotate them, and I’d suffered another attack of daydreaming. But I did notice that the teacher had drawn on a piece of large card what the solid body would look like should this rotation be performed.

The product was an impossible object: a solid with a disk of infinite radius, and two hyperbolic spires above and below the disk, each of which narrowed towards an infinitely distant point.

It was a mathematical abstraction, and held for me then as much interest as such an item should.

But that mathematical impossibility was not taught to us for no reason, and the teacher had not without reason attempted to draw it for us. In the indirect manner of all our education, that day I had seen the shape of the world on which I lived.

5

Denton and I rode through the woodland at the bottom of the range of hills… and there ahead of us was the pass.

Involuntarily, I drew back on the reins and halted the horse.

“The city!” I said. “Where is it?”

“Still by the river I should imagine.”

“Then it must have been destroyed!”

There could be no other explanation. Had the city not moved in all those thirty days, only another attack could have delayed it. By now the city should at least be in its new position in the pass.

Denton was watching me, an amused expression on his face.

“Is this the first time you’ve been so far north of optimum?” he said.

“Yes it is.”

“But you’ve been down past. What happened when you came back to the city?”

“There was an attack on,” I said.

“Yes… but how much time had elapsed?”

“More than seventy miles.”

“Was that more than you expected?”

“Yes. I thought… I’d been gone only a few days, a mile or two in time.”

“O.K.” Denton moved forward again, and I followed. “The opposite is true if you go north of optimum.”

“What do you mean?”

“Hasn’t anyone told you about the subjective time values?” My blank expression gave him the answer. “If you go anywhere south of optimum, subjective time is slowed. The further south you go, the more that occurs. In the city, the time scale is more or less normal while it is near the optimum, so that when you return from down past, it seems that the city has moved far further than possible.”

“But we’ve been north.”

“Yes, and the effect is opposite. While we ride north, our subjective time scale is speeded, so that the city appears not to have moved at all. From experience, I think you’ll find that about four days have elapsed in the city while we’ve been gone. It’s more difficult to estimate at the moment, as the city itself is further south of optimum than normal.”

I said nothing for a few minutes, trying to understand the idea.

Then: “So if the city itself could move north of optimum, it wouldn’t have so many miles to travel. It could stop.”

“No. It always has to move.”

“But if where we’ve been slows down time, the city would benefit from being there.”

“No,” he said again. “The differential in subjective time is relative.”

“I don’t understand,” I said honestly.

We were now riding up the valley towards the pass. In a few minutes we would be able to see the city, if it was indeed where Denton had predicted.

“There are two factors. One is the movement of the ground, the other is how one’s values of time are changed subjectively. Both are absolute, but not necessarily connected as far as we know.”

“Then why — ?”

“Listen. The ground moves, physically. In the north it moves slowly — and the further north one travels the slower it moves — in the south it moves faster. If it was possible to reach the most northern point we believe the ground would not move at all. On the other hand, we believe that in the south the movement of the ground accelerates to an infinite speed at the furthest extremity of the world.”

I said: “I’ve been there… to the furthest extremity.”

“You went… what? Forty miles? Perhaps more by accident? That was far enough for you to feel the effects… but only the beginning. We’re talking in terms of millions of miles. Literally… millions. Much more, some would say. The city’s founder, Destaine, thought the world was of infinite size.”

I said: “But the city has only to travel a few miles further, and it would be north of optimum.”

“That’s right… and it would make life a lot easier. We would still have to move the city, but not so often and not so far. But the problem is that it’s as much as we can do to stay abreast of optimum.”

“What is special about the optimum?”

“It’s where conditions on this world are nearest to those on Earth planet. At the optimum point our subjective values for time are normal. In addition, a day lasts for twenty-four hours. Anywhere else on this world one’s subjective time produces slightly longer or shorter days. The velocity of the ground at optimum is about one mile in every ten days. The optimum is important because in a world like this, where there are so many variables, we need a standard. Don’t confuse miles-distance with miles-time. We say the city has moved so many miles when we really mean that ten times that number of twenty-four hour days have elapsed. So we would gain nothing in real terms by being north of optimum.”

We had now ridden to the highest point of the pass. Cablestays had been erected, and the city was in the process of being winched. The militiamen were much in evidence, standing guard not only around the city itself but also at both sides of the tracks. We decided not to ride down to the city, but to wait by the stays until the winching was completed.

Denton said suddenly: “Have you read Destaine’s Directive?”

“No. I’ve heard of it. In the oath.”

“That’s right. Clausewitz has a copy. You ought to read it if you’re a guildsman. Destaine laid down the rules for survival in this world, and no one’s ever seen any reason to change them. You’d understand the world a little better, I think.”

“Did Destaine understand it?”

“I think so.”

It took another hour for the winching to be completed. There was no intervention by the tooks, and, in fact, there was no sign of them. I saw that several of the militiamen were now armed with rifles, presumably taken from the tooks killed in the last engagement.

When we went inside the city I went straight to the central calendar, and discovered that while we had been north three and a half days had elapsed.

There was a brief discussion with Clausewitz, then we were taken to see Navigator McMahon. In some detail, Denton and I described the terrain we had travelled through, pointing out the major physical features on our map. Denton outlined our suggestions for a route that the city could take, indicating the kinds of feature that might create a problem, and alternative routes around them. In fact, the terrain was in general suited to the city. The hills would mean several deviations from true north, but there were very few steep inclines, and overall the ground was some hundred feet lower at its northern point than the city’s present elevation.

“We’ll have two more surveys immediately,” the Navigator said to Clausewitz. “One five degrees to east, and one five degrees to west. Do you have men available?”

“Yes, sir.”

“I’ll convene Council today, and we’ll set your provisional route for the time being. If better terrain appears from these two new surveys, we’ll reconsider later. How soon will you be able to conduct a normal surveying pattern?”

“As soon as we can release men from Militia and Tracks,” said Clausewitz.

“They’re priorities. For the moment, these surveys will have to suffice. If the situation eases, re-apply.”

“Yes, sir.”

The navigator took our map and my video tape, and we left the Navigation chambers.

Outside, I said to Clausewitz: “Sir, I’d like to volunteer for one of the new surveys.”

He shook his head. “No. You get three days’ leave, and then you go back to the Track guild.”

“But—”

“Guild rules.”

Clausewitz turned away, and he and Denton walked towards the Futures’ room. Technically that area was mine too, but suddenly I felt excluded. Quite literally, I had nowhere to go. While I had been working outside the city I had been sleeping in one of the Militia dormitories; now, officially on leave, I wasn’t even sure where I lived. There were bunks in the Futures’ room, and I could sleep there for the moment, but I knew that I should see Victoria as soon as possible. I had been putting this off; being away from the city conveniently prevented it. I was still wondering how I could deal with the new situation with her, and the answer to that lay in meeting her. I changed my clothes, and had a shower.

6

Nothing much had changed inside the city while I’d been north, and the domestic and medical administrators were wholly preoccupied with looking after the wounded and reorganizing the sleeping accommodation. There was less sense of desperation in the faces of the people I saw, and some efforts had been made to keep the corridors clear, but even so I realized that this was probably a bad moment to try to settle a domestic issue.

Victoria was difficult to trace. After enquiring of several of the domestic administrators I was sent to a makeshift dormitory on the lowest level, but she was not there. I spoke to the woman in charge.

“You’re her ex-husband, aren’t you?”

“That’s right. Where is she?”

“She doesn’t want to see you. She’s very busy. She’ll contact you later.”

“I want to see her,” I said.

“You can’t. Now, if you’ll excuse me we’re very busy.”

She turned her back on me and continued her work. I glanced around the crowded dormitory: off-shift workers slept at one end, and there were several wounded lying in rough beds at the other. Although there were a few people moving between the beds, Victoria was not among them.

I walked back up to the Futures’ room. During the time I had been looking for Victoria I had made a decision. There was no point in my hanging around the city aimlessly; I might as well go back to work on the tracks. But first, I had decided to read Clausewitz’s copy of Destaine’s Directive.

The Futures’ room was empty but for one guildsman. He introduced himself to me as Future Blayne.

“You’re Mann’s son, aren’t you?”

“Yes.”

“Glad to see you. Have you been up future yet?”

“Yes,” I said. I liked the look of Blayne. He was not much older than myself, and he had a fresh, open face. He seemed glad to have someone to talk to; he was, he said, due to go north on one of the surveys later in the day, and would be on his own for the next few miles.

“Do we normally go north alone?” I said.

“Normally, yes. We can work in pairs if Clausewitz gives his approval, but most Futures prefer to work alone. I like company myself, find it a bit lonely up there. How about you?”

“I’ve only been up future once. That was with Future Denton.”

“How did you get on with him?”

And so we talked, amiably and without the usual guards that seemed to show up whenever I had talked to other guildsmen. I had unconsciously adopted this manner myself, and at first I suppose I might have seemed diffident in his company. Within a few minutes, though, I found his forthright manner relaxing, and soon I felt as if we were old friends.

I told him I had made a video recording of the sun.

“Did you wipe it?”

“What do you mean?”

“Erase it from the tape.”

“No… should I have?”

He laughed. “You’ll have the Navigators down on you if they see it. You’re not supposed to use the tapes for anything except cross-referenced images of the terrain.”

“Will they see it?”

“They might. If they’re satisfied with the map, they’ll probably check a few cross-references. They’re not likely to go through the whole tape. But if they do…”

“What’s wrong with it?” I said.

“Guild rules. Tape is valuable, and shouldn’t be wasted. But don’t worry about it. Why did you record the sun, anyway?”

“An idea I had. I wanted to try and analyse it. It’s such an interesting shape.”

He looked at me with new interest.

“What do you make of it?” he said.

“Inverse values.”

“That’s right. How did you work it out? Did someone tell you?”

“I remembered something from the crèche. A hyperbola.”

“Have you thought it through yet? There’s more to it than that. Have you thought about the surface area?”

“Future Denton was explaining. He said it was very large.”

Blayne said: “Not very large… infinitely large. North of the city the surface curves up until it is almost, but never quite, vertical. South of the city it becomes almost but not quite horizontal. The world is spinning on its axis, and so with an infinite radius it is spinning at infinite speed.”

He delivered this flatly and without expression.

“You’re joking,” I said.

“No I’m not. I’m perfectly serious. Where we are, near optimum, the effects of the spin are the same as they would be on Earth planet. Further south, although the angular velocity is identical, the speed increases. When you were down past, did you feel the centrifugal force?”

“Yes.”

“If you’d gone any further, you wouldn’t be here now to remember it. That force is bloody real.”

“I was told,” I said, “that nothing could travel faster than the speed of light.”

“That’s true. Nothing does. In theory the world’s circumference is infinitely long and moves at infinite speed. But there is, or there is considered to be, a point where matter ceases to exist, and serves as an effective circumference. That point is where the spinning of the world imparts a velocity on the matter equivalent to the speed of light.”

“So it’s not infinite.”

“Not quite. But bloody big. Look at the sun.”

“I have,” I said. “Often.”

“That’s the same. If it wasn’t spinning it would be, literally, infinitely large.”

I said: “Even so, in theory it is that large. How can there be room for more than one object of infinite size?”

“There’s an answer to that. You won’t like it.”

“Try me.”

“Go to the library, and find one of the astronomical books. It doesn’t matter which. They’re all Earth planet books, so they all have the same assumptions. If we were now on Earth planet we would be living in a universe of infinite size, which would be occupied by a number of large, but finite, bodies. Here the inverse is the rule: we live in a large but finite universe, occupied by a number of bodies of infinite size.”

“It doesn’t make sense.”

“I know,” said Blayne. “I said you wouldn’t like it.”

“Where are we?”

“No one knows.”

“Where is Earth planet?”

“No one knows that either.”

I said: “Down past something strange happened. I was with three girls. As we went south, their bodies changed. They—”

“Did you see anyone up future?”

“No, we… we kept away from the villages.”

“North of optimum the local people change physically. They become very tall and thin. The further north we travel, the more the physical factors change.”

“I’ve only been about fifteen miles north.”

“Then you probably wouldn’t have noticed anything peculiar. Further than thirty-five miles north of optimum, it’s very strange.”

Later, I said: “Why does the ground move?”

“I’m not sure,” said Blayne.

“Is anyone?”

“No.”

“Where is it moving to?”

“More to the point,” said Blayne, “where is it moving from?”

“Do you know?”

“Destaine said that the movement of the ground was cyclic. Fle says in his Directive that the ground is actually stationary at the north pole. Further south, it is moving very slowly towards the equator. The nearer it approaches to the equator the faster it moves, both angularly, because of the rotation, and linearly. At the furthest extreme it is moving in two directions at once at infinite speed.”

I stared at him. “But—”

“Wait… it’s not finished. The world has a southern part too. If the world was a sphere it would be called a hemisphere, but Destaine adopted it for convenience. In the southern hemisphere, the opposite is true. That is, the ground moves from the equator towards the south pole, steadily decelerating. At the south pole it is stationary again.”

“You still haven’t said where the ground moves from.”

“Destaine suggested that north and south poles were identical. In other words, once any point on the ground reaches the south pole it reappears at the north pole.”

“That’s impossible!”

“Not according to Destaine. He says that the world is shaped like a solid hyperbola; that is, all limits are infinite. If you can imagine that, the limits adopt the characteristics of their opposite value. An infinite negative becomes an infinite positive, and vice versa.”

“Are you quoting him verbatim?”

“I think so. But you should read the original.”

“I intend to,” I said.

Before Blayne left the city to go north, we agreed that when the crisis outside the city was settled we would ride together.

Alone once more, I read through the copy of Destaine’s Directive that Blayne obtained for me from Clausewitz.

It consisted of several pages of closely printed text, much of which would have been incomprehensible to me had I read it when I had first ventured outside the city. Now, with my own ideas and experiences, and with what Blayne had said, it served only to confirm. I saw some of the sense of the guild system: the experience had laid the way to understanding.

There was a lot of theoretical mathematics, interspersed with profuse calculations, at which I glanced only briefly. Of more interest was what appeared to be a hurried journal, and some sections caught my eye:

We are a long way from Earth. Our home planet is one I doubt we shall ever see again, but if we are to survive here we must maintain ourselves as a microcosm of Earth. We are in desolation and isolation. All around us is a hostile world that daily threatens our survival. As long as our buildings remain, so long shall man survive in this place. Protection and preservation of our home is paramount.

Later he wrote:

I have measured the rate of regression at one tenth of a statute mile in a period of twenty-three hours and forty-seven minutes. Although this southwards drift is slow it is relentless; the establishment shall therefore be moved at least one mile in every ten day period.

Nothing must stand in the way. We have already encountered one river, and it was crossed at great hazard. Doubtless we shall encounter further obstacles in the days and miles ahead, and by then we must be ready. We must concentrate on finding some indigenous materials that can be stored permanently within the buildings for later use as construction materials. A bridge should not be too difficult to build if we have enough warning.

Sturner has been forward and warns of a marshy region some miles ahead. Already we have sent other teams to north-east and northwest to determine the extent of this marsh. If it is not too wide we can deviate from due north for a time, and make up the difference later.

Following this entry were two pages of the theory Blayne had tried to explain to me. I read it through twice, and each time it made slightly better sense. I left it and read on. Destaine wrote:

Chen has provided the inventory of fissionable materials I requested. All of it waste! With the translat generator, no more need! Said nothing to L. I enjoy the arguments with him… why curtail them now? Future generations will be warm!

Today’s outside temperature: — 23°C. Still we move north.

Later:

Trouble with one of the caterpillar tracks. T. has advised me to authorize stripping them. Says that Sturner reports from the north that he has found what appears to be the remains of a railway line. Some incredible scheme to run the establishment along the tracks somehow. T. says it would work O.K.

Later:

Decided to create a guild system. Pleasant archaism that everyone approves. A way of structuring the organization without drastically changing the way the place is run, but I think it might impose a form to the establishment that will survive us all.

Caterpillar-track stripping proceeding well. Has caused a long delay. Hope we can catch up.

Natasha gave birth today: boy.

Doctor S. gave me some more pills. Says I’m working too hard, and have to rest. Later, maybe.

Towards the end of the Directive, a more didactic tone emerged:

What I have written here shall be privy only to those who venture outside; no need for those inside the establishment to be reminded of our dreadful prospects. We are organized enough: we have sufficient mechanical power and human initiative to maintain us safely in this world for ever more. Those who follow must learn the hard way of what will happen if we fail to exploit either our power or our initiative, and this knowledge will suffice to keep both working to the maximum.

Someone from Earth must find us one day, God willing. Until then our maxim is survival, at any cost.

From now, it has been agreed and is hereby directed:

That the ultimate responsibility lies in the hands of the Council. These men shall navigate the establishment, and be known as Navigators. Their number, which shall at no time fall below twelve, shall be elected from the senior members of the following guilds:

Track Guild: who shall be responsible for the maintenance of the rail-way along which the establishment runs;

Traction Guild: who shall be responsible for the maintenance of the motive power of the establishment;

Future Guild: who shall be responsible for surveying the lands that lie in future time of our establishment;

Bridge-Builders Guild: who shall be responsible for safe conduit over physical obstacles, should no other way be available.

Further, should it be necessary to create other guilds in the future, no guild might be created except by unanimous vote of the Council.

(signed)

Francis Destaine

The major bulk of the Directive consisted of short entries, dated in a sequence that ran from 23 February 1987 to 19 August 2023. The final signed statement was dated 24 August 2023.

There were two further sheets. One was a codicil, marking the formation of the Barter Guild and the Militia Guild. These were undated. The other sheet was a graph drawn by hand. It showed the hyperbola produced by the equation y=1/x and beneath it were some mathematical signs which I could not understand.

Such was Destaine’s Directive.

7

Outside the city, work on the tracks was proceeding well.

When I joined the track-crews, most of the rail now behind the city had been taken up, and already more crews were relaying them from the head of the pass down the long shallow valley towards the woodland at the bottom. The atmosphere had improved; helped, I think, by the successful and undisturbed winching of the city away from the river. Additionally, the gradient for the next section was in our favour. The cables and stays would have to be used, because the gradient was not sufficiently steep to overcome the effects of the centrifugal force that could be felt even here.

It was a strange sensation to stand on the ground by the city, and see it stretching out in each direction in an overall horizontal way. I knew now that this apparent levelness was no such thing; at optimum, which on the vast scale of this world was not substantially distant, the ground was actually tilted at a full forty-five degree gradient towards north. Was this, though, any different from living on the surface of a spherical world like Earth planet? I remembered a book I had read in the crèche, a book written in and about a place called England. The book was written for young children, and described the life of a family who were planning to emigrate to a place called Australia. The children in the book had believed that where they were going they would be upside-down, and the author had gone to some pains to describe how all points on a sphere appeared to be upright because of gravitational effects. So it was on this world. I had been both north and south of optimum, and always the ground appeared to be level.

I enjoyed the labours on the tracks. It was good once more to be using my body, and not give myself time to think about the other distractions.

One loose end remained stubbornly untied: Victoria.

I needed to see her, however distasteful such an interview might be, and I wanted to settle the situation soon. Until I had spoken to her, whatever the outcome, I would not feel at ease in the city.

I was now settled in my acceptance of the physical environment of the city. Very few questions remained to be answered. I understood how and why the city was moved, I was aware of the many subtle dangers that lay in wait should the city ever cease its northwards journey. I knew that the city was vulnerable and, at this very time, in imminent danger from renewed attacks, but that I felt would be resolved soon.

But none of these could settle the personal crisis of becoming alienated from a girl I had loved in the space of what seemed to me to be a few days.

As a guildsman I discovered I was allowed to attend meetings of the Council of Navigators. I could not take an active part, but no aspect of the session was closed to me as a spectator.

I was told that a meeting was to be held, and decided to attend it.

The Navigators met in a small hall set just behind the main Navigation quarters. It was disarmingly informal; I had anticipated much ceremony and air of occasion, but the fact was that the meetings were crucial to the efficient operation of the whole city, and there was a businesslike air as the Navigators came into the chamber and took their seats round a table.

Two Navigators I knew by name, Olsson and McMahon, were present, and thirteen others.

The first matter to be discussed was the military situation outside. One of the Navigators stood up, introduced himself as Navigator Thorens, and gave a succinct report of the current situation.

The Militia had established that there were still at least a hundred men in the neighbourhood of the city, and most of them were armed. According to military intelligence, their morale was low as many losses had been suffered; this contrasted sharply, the Navigator said, with the morale of our troops, who felt they could contain any further development. They were now in possession of twenty-one rifles captured from the tooks, and although there was not much ammunition, some had been captured and the Traction guild had devised a method of manufacturing small quantities.

A second Navigator confirmed that this was so.

The next report was on the condition of the city’s structure.

There was considerable discussion about how much re-building should be carried out, and how soon. It was stated that there was considerable pressure on the domestic administrators, and sleeping-accommodation was at a premium. The Navigators agreed that a new dormitory block should be given priority.

This discussion led naturally into wider issues, and these were of great interest to me.

As far as I could tell, the opinions of the Navigators present were divided. There was one school of thought of the opinion that the previous “closed city” policy should be re-introduced as soon as possible. The others thought that this had outlived its purpose, and should be permanently abandoned.

It seemed to me that this was a crucial issue, one which could radically alter the social structure of the city… and indeed, this was the undercurrent of the discussion. If the “closed” system were abandoned, it would mean that anyone growing up in the city would learn gradually the truth of the situation in which the city existed. It would mean a new way of education, and it would bring subtle changes in the powers of the guilds themselves.

In the end, after many calls for votes, and several amendments, there was a show of hands. By a majority of one it was decided not to re-introduce the “closed city” system for the time being.

More revelations followed. It transpired from the next item that there were seventeen transferred women inside the city, who had been there since before the first attack by the tooks. There was some discussion about what should be done with them. The meeting was informed that the women had said they wished to stay inside the city; it was immediately clear that it was possible that the attacks had been made in an attempt to free the women.

Another vote: the women should be allowed to stay within the city for as long as they wished.

It was also decided not to re-introduce the down past initiative test for apprentices. I understood that this has been suspended after the first attack, and several Navigators were in favour of now bringing it back. The meeting was told that twelve apprentices were known to have been killed down past, and a further five were still unaccounted for. The suspension remained for the time being.

I was fascinated by what I heard. I hadn’t realized before the extent to which the Navigators were in touch with the practicalities of the system. Nothing specific had been said, but there was a general feeling amongst some of the guildsmen that the Navigators were a group of ageing fuddy-duddies out of touch with reality. Advanced in years some of them certainly were, but their perceptions had not faded. Looking round at the mostly empty guild seats, I reflected that perhaps more guildsmen should attend the Navigators’ meetings.

There was more business to deal with. The report that Denton and I had made of the terrain to the north was presented by Navigator McMahon, with the added information that two further five-degree surveys were presently being conducted and that the results would be known within a day or two.

The meeting agreed that the city should follow the provisional route marked by Denton and myself until any better route was devised.

Finally, the subject of the city’s traction was raised by Navigator Lucan. He said that the Traction guild had come up with a scheme for moving the city slightly faster. Re-gaining ground on optimum would be a major step towards returning the city to a normal situation, he argued, and there was agreement to this.

The proposal, he said, was for the city to be put on to a continuous traction schedule. This would involve a greater liaison with the Track guild, and perhaps a greater risk of cables breaking. But he argued that as we were now short of much valuable rail stock after the burning of the bridge, the city would have to make shorter hauls. The Traction guild’s suggestion was to maintain a shorter length of track actually laid to the north of the city, and to keep the winches running permanently. They would be phased out for periodic overhaul, and as the gradients of future territory were largely in our favour we could keep the city running at a speed sufficient to bring us back to optimum within twenty or twenty-five miles of elapsed time:

There were few objections to this scheme, although the chairman called for a detailed report. When the vote was cast the result was nine in favour, six against. When the report was produced, the city would transfer to continuous running as soon as could be managed.

8

I was due to leave the city for a survey mission to the north. In the morning I had been called away from my work on the tracks, and Clausewitz had given me my briefing. I would leave the city the next day, and travel twenty-five miles to the north of optimum, reporting back on the nature of the terrain and the positions of various settlements. I was given the choice of working alone or with another Future guildsman. Recalling the new and welcome acquaintanceship with Blayne, I requested that he and I work together, and this was granted.

I was eager to leave. I felt no obligation to remain on the manual work of the tracks. Men who had never been outside the city were working well as teams, and more progress was made than at any time we had employed local labour.

The last attack by the tooks now seemed a long way behind us, and morale was good. We had made it to the pass in safety, ahead was the long slope down through the valley. The weather was fine, and hopes were high.

In the evening I returned to the inside of the city. I had decided to talk over the survey mission with Blayne, and spend the night in the Futures’ quarters. We would be ready to leave at first light.

Walking through the corridors, I saw Victoria.

She was working alone in a tiny office, checking through a large batch of papers. I went inside, and closed the door.

“Oh, it’s you,” she said.

“You don’t mind?”

“I’m very busy.”

“So am I.”

“Then leave me alone, and get on with whatever it is.”

“No,” I said. “I want to talk to you.”

“Some other time.”

“You can’t avoid me for ever.”

“I don’t have to talk to you now,” she said.

I grabbed at her pen, knocking it from her hand. Papers fell on the floor, and she gasped.

“What happened, Victoria? Why didn’t you wait for me?”

She stared down at the scattered papers, and made no answer.

“Come on… answer me.”

“It’s a long time ago. Does it still matter to you?”

“Yes.”

She was looking at me now, and I stared back at her. She had changed a lot, seemed older. She was more assured, more her own woman… but I could recognize the familiar way she held her head, the way her hands were clenched: half a fist, two fingers erect and interfolded.

“Helward, I’m sorry if you were hurt, but I’ve been through a lot too. Will that do?”

“You know it won’t. What about all the things we talked about?”

“Such as?”

“The private things, the intimacies.”

“Your oath is safe… you needn’t worry about that.”

“I wasn’t even thinking of it,” I said. “What about the other things, about you and me?”

“The whispered exchanges in bed?”

I winced. “Yes.”

“They were a long time ago.” Perhaps my reaction showed, for suddenly her manner softened. “I’m sorry, I didn’t mean to be callous.”

“O.K. Say what you like.”

“No… it’s just that, I wasn’t expecting to see you. You were gone so long! You could have been dead, and no one would tell me anything.”

“Who did you ask?”

“Your boss. Clausewitz. All he’d say was that you’d left the city.”

“But I told you where I was going. I said I had to go south of the city.”

“And you said you’d be back in a few miles’ time.”

“I know,” I said. “I was wrong.”

“What happened?”

“I… was delayed.” I couldn’t even begin to explain.

“That’s all. You were delayed?”

“It was a lot further than I thought.”

Aimlessly, she began shuffling the papers, making them into a semblance of a tidy pile. But she was just working her hands; I’d broken through.

“You never saw David, did you?”

“David? Is that what you called him?”

“He was—” She looked up at me again, and her eyes were brimming with tears. “I had to put him in the crèche, there was so much work to do. I saw him every day, and then the first attack came. I had to be on a fire point, and couldn’t — Later we went down to the—”

I closed my eyes, turned away. She put her face in her hands, started to cry. I leant against the wall, resting my face against my forearm. A few seconds later I started to cry too.

A woman came through the door quickly, saw what was hap’ pening. She closed the door again. This time I leant my weight against it to prevent further interruptions.

Later, Victoria said: “I thought you would never come back. There was a lot of confusion in the city, but I managed to find someone from your guild. He said that a lot of apprentices had been killed when they were in the south. I told him how long you had been gone. He wouldn’t commit himself. All I knew was how long you’d been gone and when you said you’d be back. It was nearly two years, Helward.”

“I was warned,” I said. “But I didn’t believe it.”

“Why not?”

“I had to walk a distance of about eighty miles, there and back. I thought I could do it in a few days. No one in the guild told me why I couldn’t.”

“But they knew?”

“Undoubtedly.”

“They could have at least waited until we’d had the child.”

“I had to go when I was told. It was part of the guild training.”

Victoria was now more composed than before; the emotional reaction had completely destroyed the antipathy that was there, and we were able to talk more rationally. She picked up the fallen papers, arranged them into a pile, then put them away into a drawer. There was a chair by the opposite wall, and I sat on it.

“You know the guild system is going to have to change,” she said.

“Not drastically.”

“It’s going to break down completely. It has to. In effect it’s happened already. Anyone can go outside the city now. The Navigators will cling to the old system for as long as they can, because they’re living in the past, but—”

“They’re not as hidebound as you think,” I said.

“They’ll try to bring back the secrecy and the suppression as soon as they can.”

“You’re wrong,” I said flatly. “I know you’re wrong.”

“All right… but certain things will have to change. There’s no one in the city now who doesn’t know the danger we’re in. We’ve been cheating and stealing our way across this land, and it’s that which has created the danger. It’s time for it to stop.”

“Victoria, you don’t—”

“You only have to look at the damage! There were thirty-nine children killed! God knows how much destruction. Do you think we can survive if the people outside keep on attacking us?”

“It’s quieter now. It’s under control.”

She shook her head. “I don’t care what the current situation looks like. I’m thinking about the long term. All our troubles are ultimately created by the city being moved. That one condition produces the danger. We move across other people’s land, we bargain for manpower to move the city, we take women into the city to have sex with men they hardly know… and all in order to keep the city moving.”

“The city can never stop,” I said.

“You see… already you are a part of the guild system. Always this flat statement, without looking at it in a wider light. The city must move, the city must move. Don’t accept it as an absolute.”

“It is an absolute. I know what would happen if it stopped.”

“Well?”

“The city would be destroyed, and everyone would be killed.”

“You can’t prove that.”

“No… but I know it would be so.”

“I think you’re wrong,” said Victoria. “And I’m not alone. Even in the last few days I’ve heard it said by others. People can think for themselves. They’ve been outside, seen what it’s like. There’s no danger apart from the danger we create for ourselves.”

I said: “Look, this isn’t our conflict. I wanted to see you to talk about us.”

“But it’s all the same. What happened to us is implicitly bound up in the ways of the city. If you hadn’t been a guildsman, we might still be living together.”

“Is there any chance… ?”

“Do you want it?”

“I’m not sure,” I said.

“It’s impossible. For me, at least. I couldn’t reconcile what I believe with accepting your way of life. We’ve tried it, and it separated us. Anyway, I’m living with—”

“I know.”

She looked at me, and I felt at second hand the alienation she had experienced.

“Don’t you have any beliefs, Helward?” she said.

“Only that the guild system, for all its imperfections, is sound.”

“And you want us to live together again, living out two separate beliefs. It couldn’t work.”

We had both changed a lot; she was right. It was no good speculating about what might have been in other circumstances. There was no way of making a personal relationship distinct from the overall scheme of the city.

Even so, I tried again, attempting to explain the apparent suddenness of what had happened, attempting to find a formula that could somehow revive the early feelings we had had for each other. To be fair, Victoria responded in kind, but I think we had both arrived at the same conclusion by our separate routes. I felt better for seeing her, and when I left her and went on towards the Futures’ quarters I was aware that we had succeeded in resolving the worst of the remaining issue.

9

The following day, when I rode north with Blayne to start the future survey, marked the beginning of a long period which produced for the city a state of both regained security and radical change.

I saw this process develop gradually, for my own sense of actual city-time was distorted by my journeys to the north. I learnt by experience that at a distance roughly twenty miles to the north of optimum, a day spent was equivalent to an hour of elapsed time in the city. As far as possible, I kept in touch with what happened in the city by attending as many Navigators’ meetings as I could.

The placidity of the city’s existence that I had experienced when I first left to work outside returned more quickly than most people had expected.

There were no more attacks by the tooks, although one of the militiamen, engaged in an intelligence mission, was captured and killed. Soon after this, the leaders of the Militia announced that the tooks were dispersing, and heading for their settlements in the south.

Although military vigilance was maintained for a long time — and never in fact wholly abandoned — gradually men from the Militia were freed to work on other projects.

As I had learnt at that first Navigators’ meeting, the method of hauling the city was changed. After several initial difficulties, the city was successfully launched into a system of continuous traction, using a complicated arrangement of alternating cables and phased track-laying. One tenth of a mile in a twenty-four hour period was not, after all, a considerable distance to move, and within a short time the city had reached optimum.

It was discovered that this actually gave the city greater freedom of movement. It was possible, for instance, to take quite considerable detours from a bearing of true north if a sufficiently large obstacle were to appear.

In fact the terrain was good. As our surveys showed, the overall elevation of the terrain was falling, and there were more gradients in our favour than were against us.

There were more rivers in this region than the Navigators would have liked, and the Bridge-Builders were kept busy. But with the city at optimum, and with its greater capacity for speed relative to the movement of the ground, there was more time available for decision-making, and more time in which to build a safe bridge.

With some hesitation at first, the barter system was reintroduced.

There was the benefit of hindsight in the city’s favour, and barter negotiations were conducted more scrupulously than before. The city paid more generously for manpower — which was still needed — and tried for a long time to avoid the necessity of bartering for transferred women.

Through a long series of Navigators’ meetings I followed the debate on this subject. We still had the seventeen transferred women inside the city who had been with us since before the first attack, and they had expressed no desire to return. But the predominance of male births continued, and there was a strong lobby for the return of the transfer system. No one knew why there should be such an imbalance in the distribution of the sexes, but it was undoubtedly so. Further, three of the transferred women had given birth within the last few miles, and each of these babies had been male. It was suggested that the longer women from outside remained in the city, the more chance there was that they too would produce male children. Again, no one understood why this should be so.

At the last count, there were now a total of seventy-six male and fourteen female children below the age of one hundred and fifty miles.

As the percentage continued to mount the lobby strengthened, and soon the Barter guild was authorized to commence negotiations.

It was actually this decision which emphasized the changes in the society of the city which were taking place.

The “open city” system had remained, and non-guildsmen were allowed to attend Navigators’ meetings as spectators. Within a few hours of the announcement about the barter for women being renewed, everyone in the city knew, and there were many voices raised in protest. Nevertheless, the decision was implemented.

Although hired labour was again being used, it was to a far lesser extent than before, and there was always a considerable number of people from the city working on the tracks and cables. There was not much that wasn’t known about the city’s operations.

But general education about the real nature of the world on which we lived was poor.

During one debate, I heard the word “Terminator” used for the first time. It was explained that the Terminators were a group of people who actively opposed the continued movement of the city, and were committed to halting it. As far as was known, the Terminators were not militant and would take no direct action, but they were gaining a considerable amount of support within the city.

It was decided that a programme of re-education should begin, to dramatize the necessity of moving the city northwards.

At the next meeting there was a violent disruption.

A group of people burst into the chamber during the session, and tried to take the chair.

I was not surprised to see that Victoria was among them.

After a noisy argument, the Navigators summoned the assistance of the Militia and the meeting was closed.

This disruption, perversely, had the effect desired by the Terminator movement. The Navigators’ meetings were once again closed to general session. The dichotomy in the opinions of the ordinary people of the city widened. The Terminators had a considerable amount of support, but no real authority.

A few incidents followed. A cable was found cut in mysterious circumstances, and one of the Terminators tried one day to speak to the hired labour in an attempt to get them to return to their villages… but by and large the Terminator movement was no more than a thorn in the side of the Navigators.

Re-education went well. A series of lectures was mounted, attempting to explain the peculiar dangers of this world, and they were well attended. The design of the hyperbola was adopted as the city’s motif, and it was worn as an ornament on the guildsmen’s cloaks, stitched inside the circle on their breasts.

I don’t know how much of this was understood by the ordinary people of the city; I overheard some discussion of it, but the influence of the Terminators perhaps weakened its credibility. For too long the people of the city had been allowed by omission to assume that the city existed on a world like Earth planet, if not Earth planet itself. Perhaps the real situation was one too outrageous to be given credence: they would listen to what they were told, and perhaps understand it, but I think the Terminators held a greater emotional appeal.

In spite of everything, the city continued to move slowly northwards. Sometimes I would take time off from other matters, and try to view it in my mind’s eye as a tiny speck of matter on an alien world; I would see it as an object of one universe trying to survive in another; as a city full of people, holding on to the side of a forty-five degree slope, pulling its way against a tide of ground on a few thin strands of cable.

With the return to a more stable environment for the city, the task of future surveying became more routine.

For our purposes the ground to the north of the city was divided into a series of segments, radiating from optimum at five degree intervals. Under normal circumstances the city would not seek a route that was more than fifteen degrees away from due north, but the city’s extra capability to deviate did allow considerable flexibility from this for short periods.

Our procedure was simple. Surveyors would ride north from the city — either alone or, if they chose, in pairs — and conduct a comprehensive survey of the segment allotted to them. There was plenty of time available to us.

On many occasions I would find myself seduced by the feeling of freedom in the north, and it was one which Blayne once told me was common to most Futures. Where was the urgency to return if a day spent lazily on the bank of a river wasted only a few minutes of the city’s time?

There was a price to pay for the time spent in the north, and it was one that did not seem real to me until I saw its effects for myself. A day spent idling in the north was a day in my life. In fifty days I aged the equivalent of five miles in the city, but the city people had aged only four days. It did not matter at first: our return visits to the city were so comparatively frequent that I saw and felt no difference. But in time, the people I had known — Victoria, Jase, Malchuskin — seemed not to have aged at all, and catching a sight of myself in a mirror one day I saw the effect of the differential.

I did not want to settle down permanently with another girl; Victoria’s notion that the ways of the city would disrupt any relationship took greater meaning every time I considered it.

The first of the transferred women were coming to the city, and as an unmarried man I was told that I was eligible to mate with one of them temporarily. At first I resisted the idea because, to be frank, the idea repelled me. It seemed to me that even a purely physical affair should have some complement in shared emotional feelings, but the manner in which the selection of the partners was arranged was as subtle as it could be under the circumstances. Whenever I was in the city I and other eligible men were encouraged to mix socially with the girls in a recreation-room set aside for this purpose. It was embarrassing and humiliating at first, but I grew used to these occasions and eventually my inhibitions waned.

In time, I formed a mutual liking with a girl named Dorita, and soon she and I were allocated a cabin we could share. We did not have much in common, but her attempts to speak English were delightful, and she seemed to enjoy my company. Soon she was pregnant, and between my surveying missions I watched her pregnancy proceed.

Slowly, so unbelievably slowly.

I began to grow increasingly frustrated with the apparently sluggish progress of the city. By my own subjective time scale, a hundred and fifty, perhaps two hundred miles had elapsed since I had become a Future guildsman, and yet the city was still in sight of those hills we had been passing through at the time of the attacks.

I applied to transfer temporarily to another guild; much as I enjoyed the leisured life in the future I felt that time was passing me by.

For a few miles I worked with the Traction guild, and it was during this period that Dorita gave birth. She produced twins: a boy and a girl. Much celebration… but I found that the city life discontented me in another way. I had been working with Jase, someone who had once been several miles older than me. Now he was clearly younger than me, and we had little in common.

Shortly after she had given birth, Dorita left the city and I returned to my own guild.

Like the Future guildsmen I had seen as an apprentice, I was becoming a misfit in the city. I enjoyed my own company, relished those stolen hours in the north, was uncomfortable when in the city. I had developed an interest in drawing, but told almost no one about it. I did my guild work as quickly and efficiently as possible, then rode off alone through the future countryside, sketching what I saw, trying to find in line drawings some expression of a terrain where time could almost stand still.

I watched the city from a distance, seeing it as alien as it was; not of this world, no longer even of me. Mile by mile it hauled itself forward, never finding, nor even seeking, a final resting place.