ahead of him. His eyes kept sliding away. He said, “A kind of emergency. My crazy team are about to wreck themselves. I don’t think we can afford to lose them.”
“Explain, please.”
“Look ahead of you and tell me if you can see a cloud formation in the shape of a human eye.”
“I see it,” said the puppeteer.
“Any idea what’s causing it?”
“Obviously it is a storm of some kind. You will already have reasoned that there will be no spiral hurricane formations on the Ringworld.”
“Oh!” Louis hadn’t even wondered about that.
“The spiral form of a hurricane derives from coriolis force, from the difference in the velocities of two air masses at different latitudes. A planet is a rotating spheroid. If two masses of air move toward each other to fill a partial vacuum, one moving north and the other south, their residual velocities will carry them past each other. Thus a whirlpool of air is formed.”
“I know what causes hurricanes.”
“Then you must realize that on the Ringworld, all contiguous masses of air have virtually the same velocity. There will be no whirlpool effect.”
Louis looked ahead of him toward the eye-shaped storm. “But what kind of a storm would you get? None at all, I’d think. You wouldn’t get any circulation of air at all.”
“Untrue, Louis. Hot air would rise, cold air would sink. But these effects could not produce such a storm as that ahead of us.”
“Too right.”
“What is Speaker threatening to do?”
“Fly through the center of that Finagle-sired thing, with Teela loyally following after him.”
The puppeteer whistled a tone as pure and beautiful as ruby laser light “That seems dangerous. The sonic folds would protect them against the ravages of any ordinary storm. But this looks to be no ordinary storm…”
“I was thinking that it might be artificial.”
“Yes…The Ringworlders would have set up their own Ring-girdling circulation system. But that system would have stopped working when the Ring power supply failed. I don’t see…ah. I have it, Louis.”
“What is it?”
“We must postulate an air-sink, a region where air disappears near the middle of the storm. All the rest follows.
“Consider. The air sink creates a partial vacuum. Air masses flow in from spinward and antispinward—”
“And port and starboard.”
“These we can ignore,” the puppeteer said crisply. “But air moving in from spinward will become fractionally lighter than the surrounding air. It will rise. Air moving in from the opposite direction, from antispinward, will become fractionally heavier—”
Louis was groping with an improperly visualized picture. “Why?”
“From antispinward it comes, Louis. Its rotational velocity is increased fractionally with respect to the Ring. Centrifugal force causes it to sink slightly.
“It forms the lower eyelid of the eye. The air from spinward, rising, forms the upper eyelid. There is a whirlpool effect, surely, but the axis of the whirlpool is horizontal, where on a planet it would be vertical.”
“But it’s such a minor effect!”
“But it is the only effect, Louis. There is nothing to interfere with its action, or to stop it. It might go on for millennia, building to what you see now.”
“Maybe. Maybe.” The eye seemed less frightening now. As the puppeteer had said, it must be some kind of storm. It was all the colors of a storm, of black clouds and upper sunlit white clouds and the dark “eye” of the storm acting as the iris of the Eye.
“The problem is the air sink, of course. Why does air disappear near the center of the storm?”
“Maybe a pump is still working in there.”
“I doubt that, Louis. If that were so, the air disturbances in this vicinity would be planned.”
“Well?”
“Have you noticed the places where the ring foundation material pokes through the soil and the bedrock? Surely such erosion must be unplanned. Have you noticed how such places appeared more frequently as we neared this place? The Eye storm must have upset weather patterns for tens of thousands of miles around, over an area greater than your world or mine.”
This time it was Louis who whistled. “Tanj for torment! But then—oh, now I see. There must be a meteor puncture in the center of the Eye storm.”
“Yes. You see the importance of this. The ring floor can be penetrated.”
“But not by anything we’re armed with.”
“True. Still, we must know if the puncture is there.”
Already Louis’s superstitious panic seemed a remembered dream. The puppeteer’s analytical calm was contagious and steadying. Louis Wu looked fearlessly into the eye and said, “We’ll have to go in and look. You think it’ll be safe, flying through the iris?”
“It