“But what would happen if we ever reached optimum?”

Malchuskin grinned. “We’d go on digging up old tracks.”

“Why?”

“Because the optimum’s always moving. But we’re not likely to reach optimum, and it doesn’t matter that much. Anywhere within a few miles of it is O.K. Put it this way… if we could get ahead of optimum for a bit, we could all have a good long rest.”

“Is that possible?”

“I guess so. Look at it this way. Where we are at the moment the ground is fairly high. To get up here we had to go through a long stretch of rising country. That was when my father was out here. It’s harder work to climb, so it took longer, and we got behind optimum. If we ever come to some lower country, then we can coast down the slope.”

“What are the prospects of that?”

“You’d better ask your guild that. Not my concern.”

“But what’s the countryside like here?”

“I’ll show you tomorrow.”

Though I hadn’t followed much of what Malchuskin said, at least one thing had become clear, and that was how time was measured. I was six hundred and fifty miles old; that did not mean that the city had moved that distance during my lifetime, but that the optimum had.

Whatever the optimum was.

The next day Malchuskin kept his promise. While the hired labourers took one of their customary rests in the deep shadow of the city, Malchuskin walked with me to a low rise of land some distance to the east of the city. Standing there we could see almost the whole of the immediate environment of the city.

It was at present standing in the centre of a broad valley, bounded north and south by two relatively high ridges of ground. To the south I could see clearly the traces of the track which had been taken up, marked by four parallel rows of scars where the sleepers and their foundations had been laid.

To the north of the city, the tracks ran smoothly up the slope of the ridge. There was not much activity here, though I could see one of the battery-driven bogies rolling slowly up the slope with its load of rail and sleepers and its attendant crew. On the crest of the ridge itself there was a considerable degree of activity, although from this distance it was not possible to determine exactly what was going on.

“Good country this,” Malchuskin said, but then immediately qualified it. “For a trackman, that is.”

“Why?”

“It’s smooth. We can take ridges and valleys in our stride. What gets me bothered is broken ground: rocks, rivers, or even forests. That’s one of the advantages of being high at the moment. This is all very old rock around here, and it’s been smoothed out by the elements. But don’t talk to me about rivers. Then I get agitated.”

“What’s wrong with rivers?”

“I said don’t talk about them!” He slapped me goodhumouredly on the shoulders, and we started our walk back towards the city. “Rivers have to be crossed. That means a bridge has to be built unless there’s one already there, which there never is. We have to wait around while the bridge is made ready, and that causes a delay. Usually, it’s the Track guild that gets the blame for delays. But that’s life. The trouble with rivers is that everyone’s got mixed feelings about them. The one thing the city’s permanently short of is water, and if we come across a river that solves one problem for the time being. But we still have to build a bridge, and that gets everyone nervous.”

The hired labourers did not look exactly pleased to see us when we returned, but Rafael moved them and work soon recommenced. The last of the tracks had now been taken up, and all we had left to do was build the last buffer. This was a steel erection, mounted above and across the last section of track, and utilizing three of the concrete sleeper foundations. Each of the four tracks had a buffer, and these were placed in such a way that if the city were to roll backwards it would be supported. The buffers were not in a line, owing to the irregular shape of the southern side of the city, but Malchuskin assured me that they were an adequate safeguard.

“I shouldn’t like them to have to be used,” he said, “but if the city did roll these should stop it. I think.”

With the completion of the buffer our work was finished.

“What now?” I said.

Malchuskin glanced up at the sun. “We ought to move house. I’d like to get my hut up across the ridge, and there are the dormitories for the workers. It’s getting late, though. I’m not sure that we could get it done before nightfall.”

“We could do it tomorrow.”

“That’s what I’m thinking. It’ll give the lazy bastards a few hours off. They’d like that.”

He spoke to Rafael, who consulted the other men. There was little doubt about the decision. Almost before Rafael had finished speaking to them, some of the men had started back towards their huts.

“Where are they going?”

“Back to their village, I expect,” said Malchuskin. “It’s just over there.” He pointed towards the south-east, over beyond the southern ridge of high ground. “They’ll be back, though. They don’t like the work but there’ll be pressure in the village, because we give them what they want.”

“What’s that?”

“The benefits of civilization,” he said, grinning cynically. “To wit, the synthetic food you’re always griping about.”

“They like that stuff?”

“No more than you do. But it’s better than an empty belly, which is what most of them had before we happened along here.”

“I don’t think I’d do all that work for that gruel. It’s tasteless, it’s got no substance, and—”

“How many meals a day did you eat in the city?”

“Three.”

“And how many were synthetic?”

“Only two,” I said.

“Well, it’s people like those poor sods who work their skins off just so you can eat one genuine meal a day. And from what I hear, what they do for me is the least of it.”

“What do you mean?”

“You’ll find out.”

Later that evening, as we sat in his hut, Malchuskin spoke more on this subject. I discovered that he wasn’t as ill-informed as he tried to make out. He blamed it all on the guild system, as ever. It had been a long established practice that the ways of the city were passed down from one generation to the next not by tuition, but on heuristic principles. An apprentice would value the traditions of the guilds far more by understanding at first hand the facts of existence on which they were based than by being trained in a theoretical manner. In practice, it meant that I would have to discover for myself how the men came to work on the tracks, what other tasks they performed, and in fact all other matters concerning the continued existence of the city.

“When I was an apprentice,” Malchuskin said, “I built bridges and I dug up tracks. I worked with the Traction guild, and rode with men like your father. I know myself how the city continues to exist, and through that I know the value of my own job. I dig up tracks and re-lay them, not because I enjoy the work but because I know why it has to be done. I’ve been out with the Barter guild and seen how they get the local people to work for us, and so I understand the pressures that are on the men who work under me now. It’s all cryptic and obscure… that’s the way you see it now. But you’ll find out that it’s all to do with survival, and just how precarious that survival is.”

“I don’t mind working with you,” I said.

“I didn’t mean that. You’ve worked O.K. with me. All I’m saying is that all the things you’ve probably wondered about — the oath, for instance — have a purpose, and by God it’s a sensible purpose!”

“So the men will be back in the morning.”

“Probably. And they’ll complain, and they’ll slacken off as soon as you or I turn our backs… but even that’s in the nature of things. Sometimes, though, I wonder.

I waited for him to finish his sentence, but he said nothing more. It was an uncharacteristic sentiment, for Malchuskin did not seem to me to be in any way a pensive man. As we sat together he fell into a long silence, broken only when I got up to go outside to use the latrine. Then he yawned and stretched, and kidded me about my weak bladder.