Viluekis said, “This grade-school teacher of yours knows nothing about anything. Just stay away from him. -Uh, did he say what his so-called easy way out was?”

“No. Should I have asked him?”

“No! Why should you have asked him? What would he know about it? But then again- All right, ask him. I'm curious what the idiot has in mind. Ask him.”

Cheryl nodded. “I can do that. But are we in trouble?” Viluekis said shortly. “Suppose you leave that to me.

We're not in trouble till I say we're in trouble.”

He looked for a long time at the closed door after she had left, both angry and uneasy. What was this Louis Martand-this grade-school teacher-doing with his lucky guesses?

If it finally came about that an extended cruise was necessary, the passengers would have to have it broken tothem carefully, or none of them would survive. With Martand shouting it to all who would listen-

Almost savagely Viluekis clicked shut the combination that would bring him the captain.

Martand was slim and of neat appearance. His lips seemed forever on the verge of a smile, though his face and bearing were marked by a polite gravity; an almost expectant gravity, as though he was forever waiting for the person with him to say something truly important.

Cheryl said to him, “I spoke to Mr. Viluekis. -He's the Fusionist, you know. I told him what you said.”

Martand looked shocked and shook his head. “I'm afraid you shouldn't have done that!”

“He did seem displeased.”

“Of course. Fusionists are very special people and they don't like to have outsiders-”

“I could see that. But he insisted there was nothing to worry about.”

“Of course not,” said Martand, taking her hand and patting it in a consoling gesture, but then continuing to hold it. “I told you there was an easy way out. He's probably setting it up now. Still, I suppose it could be awhile before he thinks of it.”

“Thinks of what?” Then, warmly, “Why shouldn't he think of it, if you have?”

“But he's a specialist, you see, my dear young lady. Specialists think in their speciality and have a hard time getting out of it. As for myself, I don't dare fall into rots. When I set up a class demonstration I've got to improvise most of the time. I have never yet been at a school where proton micropiles have been available, and I’ve had to work up a kerosene thermoelectric generator when we're off on field trips.”

“What's kerosene?” asked Cheryl.

Martand laughed. He seemed delighted. “You see? People forget. Kerosene is a kind of flammable liquid. A still-more-primitive source of energy that I have many times had to use was a wood fire which you start by friction. Did you ever come across one of those? You take a match-”

Cheryl was looking blank and Martand went on indulgently, “Well, it doesn't matter. I'm just trying to get across the notion that your Fusionist will have to think of something more primitive than fusion and that will take him a while. As for me, I'm used to working with primitive methods. -For instance, do you know what's out there?”

He gestured at the viewing port, which was utterly featureless; so featureless that the lounge was virtually depopulated for lack of a view.

“A cloud; a dust cloud.”

“Ah, but what kind? The one thing that's always to be found everywhere is hydrogen. It's the original stuff of the universe and hyperships depend on it. No ship can carry enough fuel to make repeated Jumps or to accelerate to near-light-speed and back repeatedly. We have to scoop the fuel out of space.”

“You know, I've always wondered about that. I thought outer space was empty!”

“Nearly empty, my dear, and 'nearly' is as good as a feast. When you travel at a hundred thousand miles a second, you can scoop up and compress quite a bit of hydrogen, even when there's only a few atoms per cubic centimeter. And small amounts of hydrogen, fusing steadily, provide all the energy we need. In clouds the hydrogen is usually even thicker, but impurities may cause trouble, as in this one.”

“How can you tell this one has impurities?”

“Why else would Mr. Viluekis have shut down the fusion tube. Next to hydrogen, the most common elements in the universe are helium, oxygen, and carbon. If the fusion pumps have stopped, that means there's a shortage of fuel, which is hydrogen, and a presence of something that will damage the complex fusion system. This can't be helium, which is harmless. It is possibly hydroxyl groups, an oxygen-hydrogen combination. Do you understand?”

“I think so,” said Cheryl. “I had general science in college, and some of it is coming back. The dust is really hydroxyl groups attached to solid dust grains.”

“Or actually free in the gaseous state, too. Even hydroxyl is not too dangerous to the fusion system, in moderation, but carbon compounds are. Formaldehyde is most -likely and I should imagine with a ratio of about one of those to four hydroxyls. Do you see now?”

“No, I don't,” said Cheryl flatly.

“Such compounds won't fuse. If you heat them to a few hundred million degrees, they break down into single atoms and the concentration of oxygen and carbon will simply damage the system. But why not take them in at ordinary temperatures. Hydroxyl will combine with formaldehyde, after compression, in a chemical reaction that will cause no harm to the system. At least, I'm sure a good Fusionist could modify the system to handle a chemical reaction at room temperature. The energy of the reaction can be stored and, after a while, there will be enough to make a Jump possible.”

Cheryl said, “I don't see that at all. Chemical reactions produce hardly any energy, compared to fusion.”

“You're quite right, dear. But we don't need much. The previous Jump has left us with insufficient energy for an immediate second Jump-that's regulations. But I'll bet your friend, the Fusionist, saw to it that as little energy as possible was lacking. Fusionists usually do that. The little extra required to reach ignition can be collected from ordinary chemical reactions. Then, once a Jump takes us out of the cloud, cruising for a week or so will refill our energy tanks and we can continue without harm. Of course-” Martand raised his eyebrows and shrugged.

“Yes?”

“Of course,” said Martand, “if for any reason Mr. Viluekis should delay, there may be trouble. Every day we spend before Jumping uses up energy in the ordinary life of the ship, and after a while chemical reactions won't supply the energy required to reach Jump-ignition. I hope he doesn't wait long.”

“Well, why don't you tell him? Now.”

Martand shook his head. “Tell a Fusionist? I couldn't do that, dear.”

“Then I will.”

“Oh, no. He's sure to think of it himself. In fact, I'll make a bet with you, my dear. You tell him exactly what I said and say that I told you he had already thought of it himself and that the fusion tube was in operation. And, of course, if I win-”

Martand smiled.

Cheryl smiled, too. “I'll see,” she said.

Martand looked after her thoughtfully as she hastened away, his thoughts not entirely on Viluekis's possible reaction.

He was not surprised when a ship's guard appeared from almost nowhere and said, “Please come with me, Mr. Martand.”

Martand said quietly. “Thank you for letting me finish. I was afraid you wouldn't.”

Something more than six hours passed before Martand was allowed to see the captain. His imprisonment (which was what he considered it) was one of isolation, but was not onerous; and the captain, when he did see him, looked tired and not particularly hostile.

Hanson said, “It was reported to me that you were spreading rumors designed to create panic among the passengers. That is a serious charge.”

“I spoke to one passenger only, sir; and for a purpose.”