This acceleration is partly gravity and partly centripetal. As we rise, the gravitational component lessens as the inverse square. The centripetal fraction, however, is constant and—

Killeen moved his lips soundlessly. “How… long…”

I estimate from observation (not that Grey is any use in this—she is really quite spotty in her recollections) that the object touches down into the atmosphere roughly every twenty minutes. We should experience less than two gravities for one-quarter of this period, as we swing up. That will occur in about five minutes. However, we face a worse problem before that. In fact, the effects are becoming apparent.

Killeen’s ears popped.

We are leaving the atmosphere.

It was hopeless. His arms were leaden logs. He could not reach his helmet to twist the screw-seal. And he did not know if the rugged treatment of the last few days had kept the O-rings intact.

Wind whistled through the compartment.

The shrill sound came from hair-thin seams in the wall.

For a long moment as the immense hand continued to squeeze him, Killeen could think of nothing. Then he marshaled his thoughts and let a pointed, simple message sit solidly in the forefront of his mind.

A strumming answer came. Cloudy, diffuse, as if it issued from several throats at once. The Cyber’s voice.

Yes. We will try.

Something slapped against the outside skin of the Cyber. A sticky blue glob oozed out along the seam lines. The whistling died. An acrid smoke rose from the blue fluid. Killeen knew it was some internal pap the Cyber used. It gave off a foul odor. He fought an impulse to cough and retch. But the seams held. The screech of escaping air died away.

The immense weight now lessened. Killeen could turn his head a fraction and see the screen wall.

Outside, the Skysower stretched up into blueblack emptiness. He was looking along the great chestnut-colored length of it. Shrubs nearby were flattened against the rough bark. The wind’s high bowl tore fruitlessly at them.

Skysower was a great cable stretching into the steadily darkening sky. Ebony laminations reached along it. Ash-blond segments like cross-struts connected these into a grid. They hugged the woody curve of the bark and the fierce gale could find no edge to pry them up.

The solid, implacable roar made their compartment vibrate like a living thing. Its hammering ferocity rose. Killeen wondered how long even the Cyber’s strength could hold it moored there.

Suddenly the noise muted as though someone had thrown a switch.

We are exceeding the speed of sound, I believe.

Along the towering length Killeen saw thin hickory-colored edges rise. They were like ailerons, sculpting the air. Long, strumming notes came through to Killeen.

It appears to be guiding itself like a giant flying wing. Net acceleration is lessening as we rise into the upper atmosphere. The structure is relaxing.

Pops and creaks rang out.

“I… what’s…” Toby got out between clenched teeth.

“Hold on.”

“Besen…”

“She’s quick.” Killeen tried to fill his voice with reassurance. “She’ll get away from that fight.”

Shibo’s wound was worse. He tightened her bandage but working against the heavy acceleration made him clumsy. The systems damage worried him most. He wished he could tell Toby something to relieve the anxiety he read in the boy’s face. He had no idea where they were going.

If the Cyber can cling to this for another fifteen minutes we may be able to leap off. Then we will be one-sixth of the way around the planet’s equator and quite beyond the dangers of the other Cybers.

“Yeasay,” Killeen managed to say. “And we’ll slam into the ground.”

True, our total acceleration downward will be considerable, about 2.4 gravities. But at the optimum moment, as the tip hovers over the surface, we can in principle simply step off, with only a net sidewise velocity. Then perhaps the Cyber can fly us to safety.

Such theoretical events seemed far away compared with the cycling of Shibo’s indices. Her face was untroubled and chalk white.

Outside, the last haze of blue faded into hard black. Nearby stars bit brightly at his eyes. Molecular clouds gave their gauzy wash to the vault.

Killeen’s thoughts came like thick syrup. The immense hand that pressed him to the floor had eased for a while. Now it leaned harder. His chest ached with the effort of breathing. He wondered distantly how long their air in the cramped compartment would last.

We shall be in high vacuum for about eight minutes more. I believe you can survive easily.

But Arthur did not feel the gathering ache that spread from his chest and into his arms and legs. Much more of this and Shibo would lose consciousness—which might not be a bad idea, except that Killeen did not know what they would have to do to survive. If the Cyber failed…

He could no longer afford the luxury of speculation. Living was labor enough. He turned his attention to the increasing effort of forcing breath into his lungs. His heart thudded in slow, tortured beats.

He grasped with leaden fingers for Shibo. A slight labored heave told him she still breathed.

Sluggishly he formulated a question and displayed it across his fevered and frayed consciousness.

We are Quath’jutt’kkal’thon. We carried you before.

“What… happens…”

We must cautiously adjust our dynamics.

Killeen could not understand. As he watched, the ivory curve of the planet rolled up in the wall screen. Farther away the cosmic string hung unmoving, a dull amber arc.

He felt the Cyber sway and rock in slow undulations. He could see great long swells racing toward them from the center of the Skysower. Waves excited by the air turbulence. As they reflected at the tip they gave it a sharp snap, like a whip cracking. The Cyber held on grimly.

Vibrations had moved his hand away from Shibo. He rolled to look at her and pain lanced into his shoulder. Her eyelids were sunken. He could not tell if she was still alive.

As they rose farther above the planet the whole disk became visible. Repeated sucking of the core metal had smashed the outlines of mountain ranges. Rivers now cut fresh paths. Lakes had spilled into new muddy reservoirs, leaving enormous bare brown plains.

He could see all of Skysower now. It curved like a slender snake that smoothly turned head over tail. The far end was just piercing the atmosphere. Undulations ran like waves in a long string, driven by the supersonic collision of this gargantuan living being with its blanket of air.

As he watched he slowly realized that some of the thicker vines nearby were throbbing. Bulges in them contracted rhythmically. It came to him that Skysower had to circulate its fluids, like any living thing. These coarse, chestnut-brown tubes were like vegetable hearts, working against the eternal outward thrust that came from Skysower’s spin. Somewhere beneath the grainy bark something like muscles must be sliding and clenching, to righten displacements and masses and maintain the even turning of the huge whirling organism.

Suddenly, at the edge of his vision, he saw plumes of gas burst forth at the nearby teak-colored horizon. Luminous geysers caught the sun’s rays. From the Cyber he caught a thread of understanding. To keep itself rotating, this huge thing breathed in air during its passage. Then it exhaled, perhaps burning the gases in some fashion to gain added thrust. This paid back the momentum stolen by the atmosphere’s supersonic turbulence.

All this came to him as he fought the sure rise of pressure against his chest. He thought distantly now, barely able to hold on to consciousness against the worsening weight.

Then something rushed by them and caught his attention. A second tubular shape passed nearby and he saw that hot yellow balls burned at regular intervals along its length. He remembered the forest fire. These were the trees that the vines had snagged from the forest below.