Yet they showed puzzling differences; they lacked a nucleus, as well as many of the other minimum requirements of even the most primitive terrestrial life forms. And although Laura Ernst—now doubling as research scientist as well as ship’s doctor—had proved that they definitely generated oxygen, there were far too few of them to account for the augmentation of Rama’s atmosphere. They should have existed in billions, not mere thousands. Then she discovered that their numbers were dwindling rapidly, and must have been far higher during the first hours of the Raman dawn. It was as if there had been a brief explosion of life, recapitulating on a trillionfold swifter time-scale the early history of Earth. Now, perhaps, it had exhausted itself; the drifting micro-organisms were disintegrating, releasing their stores of chemicals back into the Sea.

“If you have to swim for it,” Dr. Ernst had warned the mariners, “keep your mouths closed. A few drops won’t matter—if you spit them out right away. But all those weird organo-metallic salts add up to a fairly poisonous package, and I’d hate to have to work out an antidote.” This danger, fortunately, seemed very unlikely. Resolution could stay afloat if any two of her buoyancy tanks were punctured. (When told of this, Joe Calvert had muttered darkly: “Remember the Titanic!’) And even if she sank, the crude but efficient life jackets would keep their heads above water. Although Laura had been reluctant to give a firm ruling on this, she did not think that a few hours’ immersion in the Sea would be fatal; but she did not recommend it. After twenty minutes of steady progress New York was no longer a distant island. It was becoming a real place, and details which they had seen only through telescopes and photo-enlargements were now revealing themselves as massive, solid structures. It was now strikingly apparent that the “city”, like so much of Rama, was triplicated; it consisted of three identical, circular complexes or superstructures, rising from a long, oval foundation. Photographs taken from the Hub also indicated that each complex was itself divided into three equal components, like a pie sliced into 120-degree portions. This would greatly simplify the task of exploration; presumably they had to examine only one ninth of New York to have seen the whole of it. Even this would be a formidable undertaking; it would mean investigating at least a square kilometre of buildings and machinery, some of which towered hundreds of metres into the air.

The Ramans, it seemed, had brought the art of triple redundancy to a high degree of perfection. This was demonstrated in the airlock system, the stairways at the Hub, the artificial suns. And where it really mattered, they had even taken the next step. New York appeared to be an example of triple-triple redundancy.

Ruby was steering Resolution towards the central complex, where a flight of steps led up from the water to the very top of the wall or levee which surrounded the island. There was even a conveniently-placed mooring post to which boats could be tied; when she saw this, Ruby became quite excited. Now she would never be content until she found one of the craft in which the Ramans sailed their extraordinary sea. Norton was the first to step ashore; he looked back at his three companions and said: “Wait here on the boat until I get to the top of the wall. When I wave, Pieter and Boris will join me. You stay at the helm, Ruby, so that we can cast off at a moment’s notice. If anything happens to me, report to Karl and follow his instructions. Use your best judgement—but no heroics. Understood?”

“Yes, Skipper. Good luck!”

Commander Norton did not really believe in luck; he never got into a situation until he had analysed all the factors involved and had secured his line of retreat. But once again Rama was forcing him to break some of his cherished rules. Almost every factor here was unknown—as unknown as the Pacific and the Great Barrier Reef had been to his hero, three and a half centuries ago… Yes, he could do with all the luck that happened to be lying around. The stairway was a virtual duplicate of the one down which they had descended on the other side of the Sea; doubtless his friends over there were looking straight across at him through their telescopes. And “straight” was now the correct word; in this one direction, parallel to the axis of Rama, the Sea was indeed completely flat. It might well be the only body of water in the universe of which this was true, for on all other worlds every sea or lake must follow the surface of a sphere, with equal curvature in all directions.

“Nearly at the top,” he reported, speaking for the record and for his intently listening second-in-command, five kilometres away, still completely quiet—radiation normal. I’m holding the meter above my head, just in case this wall is acting as a shield for anything. And if there are any hostiles on the other side, they’ll shoot that first.” He was joking, of course. And yet—why take any chances, when it was just as easy to avoid them? When he took the last step, he found that the flat-topped embankment was about ten metres thick; on the inner side, an alternating series of ramps and stairways led down to the main level of the city, twenty metres below. In effect, he was standing on a high wall which completely surrounded New York, and so was able to get a grandstand view of it. It was a view almost stunning in its complexity, and his first act was to make a slow panoramic scan with his camera. Then he waved to his companions and radioed back across the Sea: “No sign of any activity—everything quiet. Come on up—we’ll start exploring.”

It was not a city; it was a machine. Norton had come to that conclusion in ten minutes, and saw no reason to change it after they had made a complete traverse of the island. A city—whatever the nature of its occupants—surely had to provide some form of accommodation: there was nothing here of that nature, unless it was underground. And if that was the case, where were the entrances, the stairways, the elevators? He had not found anything that even qualified as a simple door…

The closest analogy he had ever seen to this place on Earth was a giant chemical processing plant. However, there were no stockpiles of raw materials, or any indications of a transport system to move them around. Nor could he imagine where the finished product would emerge—still less what that product could possibly be. It was all very baffling, and more than a little frustrating.

“Anybody care to make a guess?” he said at last, to all who might be listening. “If this is a factory, what does it make? And where does it get its raw materials?”

“I’ve a suggestion, Skipper,” said Karl Mercer, over on the far shore. “Suppose it uses the Sea. According to Doc, that contains just about anything you can think of.” It was a plausible answer, and Norton had already considered it. There could well be buried pipes leading to the Sea—in fact, there must be, for any conceivable chemical plant would require large quantities of water. But he had a suspicion of plausible answers; they were so often wrong. “That’s a good idea, Karl; but what does New York do with its seawater?” For a long time, nobody answered from ship, Hub or Northern plain. Then an unexpected voice spoke. “That’s easy, Skipper. But you’re all going to laugh at me.”

“No, we’re not, Ravi. Go ahead.”

Sergeant Ravi McAndrews, Chief Steward and Simp Master, was the last person on this ship who would normally get involved in a technical discussion. His IQ was modest and his scientific knowledge was minimal, but he was no fool and had a natural shrewdness which everyone respected.

“Well, it’s a factory all right, Skipper, and maybe the Sea provides the raw material… after all, that’s how it all happened on Earth, though in a different way… I believe New York is a factory for making—Ramans.”