“How are you going to get at us?” he asked bluntly.
There was only the briefest of hesitations before Lawrence answered.
“I’ve not worked out the details, but we’ll add another sec tion to the caisson and continue it down until it reaches you. Then we’ll start scooping out the dust until we get to the bottom. That will take us to within a few centimeters of you; we’ll cross that gap somehow. But there’s one thing I want you to do first.”
“What’s that?”
“I’m ninety per cent sure that you won’t settle again–but if you’re going to, I’d rather you did it now. I want you all to jump up and down together for a couple of minutes.”
“Will that be safe?” asked Pat doubtfully. “Suppose this pipe tears out again?”
“Then you can plug it again. Another small hole won’t matter–but another subsidence will, if it happens when we’re trying to make a man-sized opening in the roof.”
_Selene_ had seen some strange sights, but this was undoubtedly the strangest. Twenty-two men and women were solemnly jumping up and down in unison, rising to the ceiling and then pushing themselves back as vigorously as possible to the floor. All the while Pat kept a careful watch on that pipe leading to the upper world; after a minute’s strenuous exertion on the part of her passengers, _Selene_ had moved downward by less than two centimeters.
He reported this to Lawrence, who received the news with thankfulness. Now that he was reasonably sure that Selene would not shift again, he was confident that he could get these people out. Exactly how, he was not yet certain, but the plan was beginning to form in his mind.
It took shape over the next twelve hours, in conferences with his brains trust and experiments on the Sea of Thirst. The Engineering Division had learned more about the dust in the last week than during the whole of its previous existence. It was no longer fighting in the dark against a largely unknown opponent. It understood which liberties could be taken, and which could not.
Despite the speed with which the changed plans were drawn up and the necessary hardware constructed, there was no undue haste and certainly no carelessness. For this was another operation that had to work the first time. If it failed, then at the very least the caisson would have to be abandoned and a new one sunk. And at the worst–those aboard Selene would be drowned in dust.
“It’s a pretty problem,” said Tom Lawson, who liked pretty problems–and not much else. “The lower end of the caisson’s wide open to the dust, because it’s resting against Selene at only one point, and the tilt of the roof prevents it from sealing. Before we can pump out the dust, we have to close that gap.
“Did I say ‘pump’? That was a mistake. You can’t pump the stuff; it has to be lifted. And if we tried that as things are now, it would flow in just as fast at the bottom of the tube as we took it out of the top.”
Tom paused and grinned sardonically at his multimillion audience, as if challenging it to solve the problem he had outlined. He let his viewers stew in their own thoughts for a while, then picked up the model lying on the studio table. Though it was an extremely simple one, he was rather proud of it, for he had made it himself. No one could have guessed, from the other side of the camera, that it was only cardboard sprayed with aluminum paint.
“This tube,” he said, “represents a short section of the caisson that’s now leading down to _Selene_–and which, as I said, is full of dust. Now _this_–” with his other hand, he picked up a stubby cylinder, closed at one end–“fits snugly inside the caisson, like a piston. It’s very heavy, and will try to sink under its own weight. But it can’t do so, of course, while the dust is trapped underneath it.”
Tom turned the piston until its flat end was toward the camera. He pressed his forefinger against the center of the circular face, and a small trap door opened.
“This acts as a valve. When it’s open, dust can flow through and the piston can sink down the shaft. As soon as it reaches the bottom, the valve will be closed by a signal from above. That will seal off the caisson, and we can start scooping out the dust.
“It sounds very simple, doesn’t it? Well, it’s not. There are about fifty problems I haven’t mentioned. For example, as the caisson is emptied, it will try to float up to the surface with a lift of a good many tons. Chief Engineer Lawrence has worked out an ingenious system of anchors to hold it down.
“You’ll realize, of course, that even when this tube has been emptied of dust, there will still be that wedge-shaped gap between its lower end and _Selene’s_ roof. How Mister Lawrence proposes to deal with that, I don’t know. And please don’t send me any more suggestions; we’ve already had enough half-baked ideas on this program to last a lifetime.
“This-piston gadget–isn’t just theory. The engineers here have built and tested it during the last twelve hours, and it’s now in action. If I can make any sense of the signals the man’s waving at me, I think we’re now going over to the Sea of Thirst, to find out what’s happening on the raft.”
The temporary studio in the Hotel Roris faded from a million screens; in its place was the picture that, by this time, must have been familiar to most of the human race.
There were now three igloos of assorted sizes on or around the raft; as the sunlight glinted from their reflecting outer surfaces, they looked like giant drops of mercury. One of the dustskis was parked beside the largest dome; the other two were in transit, still shuttling supplies from Port Roris.
Like the mouth of a well, the caisson projected from the Sea. Its rim was only twenty centimeters above the dust, and the opening seemed much too narrow for a man to enter. It would, indeed, have been a very tight fit for anyone wearing a space suit–but the crucial part of this operation would be done without suits.
At regular intervals, a cylindrical grab was disappearing into the well, to be hauled back to the surface a few seconds later by a small but powerful crane. On each withdrawal, the grab would be swung clear of the opening, and would disgorge its contents back into the Sea. For an instant a gray dunce’s cap of dust would stand in momentary balance on the level plain; then it would collapse in slow motion, vanishing completely before the next load had emerged from the shaft. It was a conjuring trick being carried out in broad daylight, and it was fascinating to watch. More effectively than a thousand words of description, it told the viewers all that they needed to know about the Sea of Thirst.
The grab was taking longer on its journeys now, as it plunged deeper into the dust. And at last there came the moment when it emerged only half full, and the way to _Selene_ was open– except for that roadblock at the end.
Chapter 29
“We’re still in very good spirits,” said Pat, into the microphone that had now been lowered down the air shaft. “Of course, we had a bad shock after that second cave-in, when we lost contact with you–but now we’re sure you’ll soon have us out. We can hear the grab at work, as it scoops up the dust, and it’s wonderful to know that help is so close. We’ll never forget,” he added, a little awkwardly, “the efforts that so many people have made to help us, and whatever happens we’d like to thank them. All of us are quite sure that everything possible has been done.
“And now I’ll hand over the mike, since several of us have messages we want to send. With any luck at all, this will be the last broadcast from _Selene_.”
As he gave the microphone to Mrs. Williams, he realized that he might have phrased that last remark a little better; it could be interpreted in two ways. But now that rescue was so close at hand, he refused to admit the possibility of further setbacks. They had been through so much that, surely, nothing more would happen to them now.
Yet he knew that the final stage of the operation would be the most difficult, and the most critical, of all. They had discussed it endlessly during the last few hours, ever since Chief Engineer Lawrence had explained his plans to them. There was little else to talk about now that, by common consent, the subject of flying saucers was vetoed.