is often inversely proportional to its length. For his amusement-and, more important, because it would help to fix the other participants in his mind -Duncan had tried to compose a formal opening, based on the list of guests that Professor Washington had provided. It started off: “Madame President, Mr. Vice President, Honorable

Chief Justice, Honorable Leader of the Senate, Honorable Leader of the

House, Your Excellencies the Ambassadors for Luna, Mars, Mercury, Ganymede, and Titan”-at this point he would incline his head slightly toward

Ambassador Farrell, if he could see him in the crowded gallery’distinguished representatives from Albania, Austrand, Cyprus, Bohemia,

France, Khmer, Palestine,

Kalinga, Zimbawe, Eire He calculated that if he acknowledged all the fifty or sixty regions that still insisted on some form of individual recognition, a quarter of his time would be expended before he had even begun. This, obviously, was absurd, and he hoped that all the other speakers would agree. Regardless of protocol, Duncan had decided to opt for dignified brevity.

“People of Earth” would cover a lot of ground-to be precise, five times the area of Titan, an impressive statistic which Duncan knew by heart. But that would leave out the visitors; what about “Friends from other worlds”? No, that was too pretentious, since most of them would be complete strangers.

Perhaps: “Madame President, distinguished guests, known and unknown friends from many worlds…” That was better, yet somehow it still didn’t seem right.

There was more to this business, Duncan realized, than met the eye, or the ear. Plenty of people would be willing to give him advice, but he was determined, in the good old Makenzie tradition, to see what he could do himself before calling for help. He had read somewhere that the best way to learn to swim is by being thrown into deep water. Duncan could not swim -that skill being singularly useless on Titan-but he could appreciate the analogy. His career in Solar politics would start with a spectacular splash, and before the eyes of millions.

It was not that he was nervous; after all, he had addressed his whole

world as an expert witness during technical debates in the Assembly. He had acquitted himself well when he weighed the complex arguments for and against mining the ammonia glaciers of

Mount Nansen. Even Armand Helmer had congratulated him, despite the fact that they had reached opposing conclusions. In those debates, affecting the future of Titan, he had had real responsibility, and his career might have come to an abrupt end if he had made a fool of himself. His Terran audience might be a thousand times larger, but it would be very much less critical. Indeed, his listeners would be friendly unless he committed the unpardonable sin of boring them.

This, however, he could not yet guarantee, for he still had no idea how he was going to use the most important ten minutes of his life.

Is

AT THE NODE

0 n the seas of Earth, they had called it

“Crossing the Line.” Whenever a ship had passed from one hemisphere to another, there had been light hearted ceremonies and rituals, during which those who had never traversed the Equator before were subjec I ted to ingenious indignities by Father Neptune and his Court.

During the first centuries of space flight, the equivalent transition involved no physical changes; only the navigational computer knew when a ship had ceased to fall toward one planet and was beginning to fall toward another. But now, with the advent of constant acceleration drives, which could maintain thrust for the entire duration of a voyage, Midpoint, or

“Turnaround,” had a real physical meaning, and a correspondingly enhanced psychological impact. After living and moving for days in an

apparent gravitational field, 84 Sirius’ passengers would lose all weight for several hours, and could at least feel that they were really in space.

They could watch the slow rotation of the stars as the ship was swung through one hundred eighty degrees, and the drive was aimed precisely against its previous line of thrust, to slowly whittle away the enormous velocity built up over the preceding ten days. They could savor the thought that they were now moving faster than any human beings in history-and could also contemplate the exciting prospect that if the drive failed to restart,

Sirius would ultimately reach the nearest stars, in not much more than a thousand years…. All these things they could do; however, human nature having certain invariants, a majority of Sirius’ passengers had other possibilities in mind.

It was the only chance most of them would ever have of experiencing weightlessness long enough to enjoy it. What a crime to waste the opportunity! No wonder that the most popular item in the ship’s library these last few days had been the Nasa Sutra, an old book and an old joke, explained so often that it was no longer funny.

Captain Ivanov denied, with a reasonably convincing show of indignation, that the ship’s schedule had been designed to pander to the passenger’s lower instincts. When the subject had been raised at the Captain’s table, the day before Turnaround, he had put up quite a plausible defense.

“It’s the only logical time to shut down the Drive,” he had explained.

“Between zero zero and zero four, all the passengers will be in their cabins, er, sleeping. So there will be the minimum of disturbance. We couldn’t close down during the day-remember, the kitchens and the toilets will be out of action while we’re weightless. Don’t forget that! We’ll remind everyone in the late evening, but some idiot always gets overconfident, or drinks too much, and doesn’t have enough sense to read the instructions on those little plastic bags you’ll find in your cabins-no thanks, Steward, I don’t feel like soup.”

Duncan had been tempted; Marissa was beginning to fade, and there was no lack of opportunity. He had received unmistakable signals from several directions, and for groups with all values of n from one to five. It would not have been easy to make a choice, but Fate had saved him the trouble.

It was a full week, and Turnaround was only three days ahead, before he had felt confident enough of his increasing intimacy with Chief Engineer

Mackenzie to drop some gentle hints. They had not been rejected out of hand, but Warren obviously wanted time to weigh the possibilities. He gave

Duncan his decision only twelve hours in advance.

“I won’t pretend this might cost me nay job,” he said, “but it could be embarrassing, to say the least, if it got around. But you are a Makenzie, and a Special Assistant to the Administrator, and all that. If the worst comes to the worst, which I hope it won’t, we can say your request’s official.”

“Of course. I understand completely, and I really appreciate what you’re doing. I won’t let you down.” . “Now there’s the question of timing. If everything checks out smoothly-and I’ve no reason to expect otherwise-I’ll be through in two hours and can dismiss my assistants. They’ll leave like meteors-they’ll all have something lined up, you can be sure of that -so we’ll have the place to ourselves. I’ll give you a call at zero two, or as soon after as possible.”

“I hope I’m not interrupting any~ ah-personal plans you’ve made.”

“As it happens, no. The novelty’s worn off. What are you smiling at?”

“It’s just occurred to me,” Duncan answered, “that if anyone does meet the pair of us at two o’clock on the morning of Turnaround, we’ll have a perfect alibi …. “

Nevertheless, he felt a mild sense of guilt as he drifted along the corridors behind Warren Mackenzie. The weightless-but far from sleeping-ship might have been deserted, for there was no occasion now for anyone to descend below the freight deck on Level Three. It was not even necessary to pretend that they were heading for an innocent assignation.