Back in the galley, they pressed their ears against the outer door, and listened for a long time to that mysterious crepitation. Presently McKenzie said: “The dust's moving, all right-but I don't see why. That gives us another puzzle to worry about.”

“Another?”

“Yes. I don't understand what's happening to the temperature. It's still going up, but nothing like as fast as it should.”

The physicist seemed really annoyed that his calculations had proved incorrect, but to Pat this was the first piece of good news since the disaster.

“Don't look so miserable about it; we all make mistakes. And if this one gives us a few more days to live, I'm certainly not complaining.”

“But I couldn't have made a mistake. The math is elementary. We know how much heat twenty-two people generate, and it must go somewhere.”

“They won't produce so much heat when they're sleeping; maybe that explains it.”

“You don't think I'd overlook anything so obvious as that!” said the scientist testily. “It helps, but it isn't enough. There's some other reason why we're not getting as hot as we should.”

“Let's just accept the fact and be thankful,” said Pat. “Meanwhile, what about this noise?”

With obvious reluctance, McKenzie switched his mind to the new problem.

“The dust's moving, but we aren't, so it's probably merely a local effect. In fact, it only seems to be happening at the back of the cabin. I wonder if that has any significance.” He gestured to the bulkhead behind them. “What's on the other side of this?”

“The motors, oxygen reserve, cooling equipment .. .”

“Cooling equipment! Of course! I remember noticing that when I came aboard. Our radiator fins are back there, aren't they?”

“That's right.”

“Now I see what's happened. They've got so hot that the dust is circulating, like any liquid that's heated. There's a dust fountain outside, and it's carrying away our surplus heat. With any luck, the temperature will stabilize now. We won't be comfortable, but we can survive.”

In the crimson gloom, the two men looked at each other with a dawning hope. Then Pat said slowly: “I'm sure that's the explanation. Perhaps our luck's beginning to turn.”

He glanced at his watch, and did a quick mental calculation.

“The sun's rising over the Sea about now. Base will have the dust-skis out looking for us, and they must know our approximate position. Ten to one they'll find us in a few hours.”

“Should we tell the Commodore?”

“No, let him sleep. He's had a harder day than any of us. This news can wait until morning.”

When McKenzie had left him, Pat tried to resume his interrupted sleep. But he could not do so; he lay with eyes open in the faint red glow, wondering at this strange turn of fate. The dust that had swallowed and then had threatened to broil them had now come to their aid, as its convection currents swept their surplus heat up to the surface. Whether those currents would continue to flow when the rising sun smote the Sea with its fall fury, he could not guess.

Outside the wall, the dust still whispered past, and suddenly Pat was reminded of an antique hourglass he had once been shown as a child. When you turned it over, sand poured through a narrow constriction into the lower chamber, and its rising level marked the passage of the minutes and the hours.

Before the invention of clocks, myriads of men must have had their days divided by such falling grains of sand. But none until now, surely, had ever had his life span metered out by a fountain of rising dust.

CHAPTER 7

In Clavius City , Chief Administrator Olsen and Tourist Commissioner Davis had just finished conferring with the Legal Department. It had not been a cheerful occasion; much of the time had been spent discussing the waivers of responsibility which the missing tourists had signed before they boarded Selene. Commissioner Davis had been much against this when the trips were started, on the grounds that it would scare away customers, but the Administration's lawyers had insisted. Now he was very glad that they had had their way.

He was glad, also, that the Port Roris authorities had done the job properly; matters like this were sometimes treated as unimportant formalities and quietly ignored. There was a full list of signatures for Selene's passengers—with one possible exception that the lawyers were still arguing about.

The incognito Commodore had been listed as R. S. Hanson, and it looked very much as if this was the name he had actually signed. The signature was, however, so illegible that it might well have been “Hansteen.” Until a facsimile was radioed from Earth, no one would be able to decide this point. It was probably unimportant. Because the Commodore was traveling on official business, the Administration was bound to accept some responsibility for him. And for all the other passengers, it was responsible morally, if not legally.