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.