“That’s the logic,” Molly agreed.
“Well, where’s the hole in it? Don’t you believe it any more?”
“There’s a healthy doubt growing. This place could be a sponge rather than an iceberg. In any case, with no ice vaporizing, air would have to be blowing in to match what blows out, and we should have as good a chance going upwind as down—especially since two downwind searches have failed us now.”
“Three, if you count the hunt for the original entry,” pointed out Carol.
“All right, three.”
“But going upstream, a river tends to subdivide into smaller and smaller streams,” Charley pointed out. “Downstream it gets bigger. I’d think…”
“This isn’t a river, which cuts its own path,” Carol interrupted. “We don’t know what made this labyrinth, and so far we’ve observed only one of its surface connections. Frankly, I’d rather be moving. There was a river in the other tunnel, and maybe it will give some guidance. The only other thing we have is wind; the only choices we have are with or against, and I’m with Molly for the moment—let’s try against, as fast as the machine will take us.”
“How about recovering the other robot?” Carol thought for a moment.
“If you can put up with its loss, Joe, I think I’d rather not commit myself to an endless running back and forth keeping the two together, even if we are near the ground most or all of the time. If a sudden drop takes us by surprise, the way it did Molly awhile ago, it might be hard to get back together. I think it would be best if we rode the same machine, however uncomfortable.”
“If you think that’s safest, do it that way. We can replace robots. Go ahead as you suggest. We’ll follow, as nearly overhead as we can, in the boat as long as there is any contact with the one you’re riding.” The women agreed briefly, and Carol sent their mount downward more rapidly than she had risked up to this point.
Molly kept her light beamed below and gave warning as the liquid surface approached. They were out of sight of the cavern wall, and not even the Shervah was precisely sure of direction, but she sent the cylinder quickly in what she hoped was more or less the right one.
It took two or three minutes to reach the edge of the lake, grown thicker with the grass here; Molly wondered whether time or location had made the difference. The arrival brought no relief.
“Joe! Charley! The level is higher! There’s no place along the edge to travel now. It’s right against the cave wall and partway up—I can’t tell how far.”
“About three meters since we were last here. The passages we used—yours and mine both—are off to the right,” Carol interjected.
“How far?”
“Yours, about seven hundred meters. We’d better hurry.” “Why?”
“Do you want to ride, swim, or get washed down that passage?”
“I’m not sure I want to go along it at all now.” “You’d rather wait until this place fills with ammonia?” “It couldn’t!”
“I’d like to believe that, too. Where’s the stuff coming from? How big is the source? Maybe it’s going to keep raining into the lakes in this neighborhood for the next twenty years. Maybe one of the lakes up above is draining into these caves.”
“But…”
“Come.” Carol said only the one word, and Molly regained her self-control. Of course her little friend was right.
Unless the ammonia turned out to be coming in from below ...
Carol sent the robot on.
Chapter Sixteen
Of Course He’d Fail
“What if the passage you’re looking for is already full of ammonia?” Charley asked anxiously.
“I don’t see how it could be.” Molly comforted him and herself. “There’s a lot of space—I have no idea how much, but I’m almost sure it’s more than this cavern here, judging by my own wanderings—to fill once it starts overflowing that way. The stream should be flowing again, though; maybe that will be some sort of guide.” “Not to the surface!”
“Well, no. But at least this particular place would have to be filling very fast indeed to cover that opening completely. We don’t have to worry about being able to get into it, I’d guess.”
“You mean you’ll go down that passage, away from the surface, in spite of…”
“Unless,” snapped Carol, “you can tell us that the storm up there, which is blowing sand fast enough to block our original entrance with a mountain-sized dune and apparently precipitating enough liquid to fill sizable caverns, is either a very small one or is about to end, yes. We are going down that passage if there is wind coming out of it. If not, we will go down any other passage we can find wind coming out of. I can’t see anything else to do. If this idiotic ball of salt kept its surface features from one century to the next—at least we can see why there was no way to match our maps with the old ones—or had a magnetic field strong enough for an ordinary person to feel, or Joe had provided some way for a person riding this robot to read its inertial sensor…”
“I did, in the new one.” An interruption by Joe was so startling that even Carol, playing straighten-out-Charley, was silenced for a moment.
Her attention shifted. “Good. Thanks. We’ll still have to use air currents for a guide, though, and following rivers upstream doesn’t seem very promising, as Charley pointed out awhile ago. For one thing, if this turns into a real river, it will probably have started out at the top from seepage; and I’m not that small. I also think we’ll have to drop this policy of keeping the robot down to a speed we can catch on foot. We don’t know how far we’ll have to go.” “But if one of you falls off…”
“If Molly falls off, I can stop the thing and wait or go back for her. If I—I’d better not.”
“I still have some surplus water,” Molly said thoughtfully. “I’d rather not use it for glazing robots, of course. But maybe we could rig some kind of gadget that would let me stop the thing with a single key—I know the controls well enough; it’s just that my hand is too big to get at them, even if I take off a glove and risk freezing my skin to the metal. All I really need is a piece of stiff wire about twenty centimeters long. I can see in as long as my light’s working—at least the keyboard faces the opening in the body! That’s luck. With Joe’s tendrils, it didn’t really have to. Sorry, Joe; that was unkind.”
“Deserved, I fear. On a less painful note, what do you have in your armor or equipment that will let you reach the keys?”
“Until I figure that out, we’ll keep multiple safety lines attached to Carol. Here comes the tunnel, doesn’t it, Carrie?”
“Yes. This lake’s draining into it, as you thought it might. We can get in at the farther side, where the opening is high enough for the robot, and see how full the stream is…”
“And whether there is any wind!” exclaimed Charley.
“And whether there is any wind,” admitted the Shervah. “That first, actually. You’ll have to duck more than I will, big friend; here it comes.”
Charley, far above, waited tensely. He could not picture clearly how close the women would have to come to the flood he imagined spilling down into Enigma’s bowels and was visualizing the worst. His faith that none of them, especially Molly, could be in real physical danger was eroding u trifle, to his own surprise, though he considered the underlying theory still valid. He continued to expect that the Human would report a new situation at any moment now, which would further complicate the group’s assigned test, but he was finding it harder and harder to feel sure that this was all that would happen. He wished briefly that he could see, or even hear, directly what was going on so far below, instead of getting everything via translators.