clouds, then the wall of bay doors on the other side. They were in a spin. Horza looked over at Wubslin as he

fought with the controls. The

engineer was staring at the main screen with a glazed expression on his face. “Wubslin!" Horza

screamed. The fusion motors stayed dead.

“Aaah!" Wubslin seemed to have woken up to the fact that they were falling out of control; he leaped at the controls in front

of him. “Just fly

it!" he shouted. “I’ll try the primers! Must have over-pressured the motors!"

Horza wrestled with the controls while Wubslin tried to restart the engines. On the screen, walls spun crazily about them

and clouds beneath

them were coming up fast—beneath them; really beneath them; a dead flat layer of clouds. Horza shook the

controls again.

The nose motor burst into life, guttering wildly, sending the spinning craft careering off toward one side of the artificial

cliff of bay doors and

walls. Horza cut the motor out. He steered into the spin, using the craft’s control surfaces rather

than the motors, then he aimed the whole ship

straight down and put his fingers on the laser buttons again. The clouds flashed

up to meet the vessel. He closed his eyes and squeezed the

laser controls.

The Ends of Invention

was so huge it was built on three almost totally separate levels, each over three kilometers deep. They were

pressure levels,

there because otherwise the differential between the very bottom and the very top of the giant ship would have been the

difference

between standard sea level and a mountaintop somewhere in the tropopause. As it was, there existed a three-and-a-half-thousand-

meter

difference between the base and roof of each pressure level, making sudden journeys by traveltube from one to the other inadvisable.

In

the immense open cave that was the hollow center of the GSV the pressure levels were marked by force fields, not anything

material, so that

craft could pass from one level to another without having to go outside the vessel, and it was toward one

of those boundaries, marked by cloud,

that the

Clear Air Turbulence

was falling.

Firing the laser did no good whatsoever, though Horza didn’t know that at the time. It was a Vavatch computer, which had taken

over the

internal monitoring and control from the Culture’s own Minds, which opened a hole in the force field to let the falling

vessel through. It did so in

the mistaken assumption that less damage would be caused to

The Ends of Invention

by letting the rogue vessel fall through than having it

impact.

In the center of a sudden maelstrom of air and cloud, in its own small hurricane, the

CAT

burst through from the thick air at the bottom of one

pressure level and into the thin atmosphere at the top of the one below.

A vortex of rag-clouded air blew out after it like an inverted explosion.

Horza opened his eyes again and saw with relief

the distant floor of the GSV’s cavernous interior, and the climbing figures on the main fusion

motors’ monitor screens. He

hit the engine throttles again, this time leaving the nose motor alone. The two main engines caught, shoving Horza

back in

his seat against the cloying hold of the restrainer fields. He pulled the nose of the diving craft up, watching the floor

far below gradually

disappear from view as it was replaced by the sight of another wall of opened bay doors. The doors were

much larger than those of the

Smallbays in the level they had just left, and the few craft Horza could see either nosing into

or appearing out of the lit lengths of the huge

hangars were full-size starships.

Horza watched the screen, piloting the

Clear Air Turbulence

exactly like an aircraft. They were traveling quickly along a vast corridor over a

kilometer across, with the layer of clouds

about fifteen hundred meters above them. Starships were moving slowly through the same space, a

few on their own AG fields,

most towed by light lifter tugs. Everything else was moving slowly and without a fuss; only the

CAT

disturbed the

calm of the giant ship’s interior, screaming through the air on twin swords of brilliant flame pulsing from

white-hot plasma chambers. Another

cliff-face of huge hangar doors faced them. Horza looked about him at the curve of main

screen and pulled the

CAT

over on a long banking left

turn, diving a little at the same time to head down an even broader canyon of space. They flashed

over a slow-moving clipper being towed

toward a distant open Mainbay, rocking the starship in their wake of superheated air.

The wall of doors and opened entrances slanted toward

them as Horza tightened the turn. Ahead, Horza could see what looked

like a cloud of insects: hundreds of tiny black specks floating in the air.

Far beyond them, maybe five or six kilometers away, a thousandmeter square of blackness, bordered with a slowly flashing strip

of

subdued white light, was the exit from

The Ends of Invention.

It was a straight run.

Horza sighed and felt his whole body relax. Unless they were intercepted, they had done it. With a little luck now, they might

even get away

from the Orbital itself. He gunned the engines, heading for the inky square in the distance.

Wubslin suddenly sat forward, against the pull of acceleration, and punched some buttons. His repeater screen set in the console

magnified

the center section of the main screen, showing the view ahead. “They’re people!" he shouted.

Horza frowned over at the man. “What."

“People! Those are people! They must be in AG harnesses! We’re going to go right through them!"

Horza looked briefly over at Wubslin’s repeater screen. It was true; the black cloud which almost filled the screen was made

up of humans,

flying slowly about in suits or ordinary clothes. There were thousands of them, Horza saw, less than a kilometer

ahead, and closing quickly.

Wubslin was staring at the screen, waving his hand at the people. “Get out of the way! Get out

of the way!" he was shouting.

Horza couldn’t see a way round, over or beneath the mass of flying people. Whether they were playing some curious mass aerial

game or

were just enjoying themselves, they were too many, too close, too widespread. “Shit!" Horza said. He got ready to

cut the rear plasma motors

before the

Clear Air Turbulence

went into the cloud of humans. With luck they might make it through before they had to relight them, and so not

incinerate

too many people.

“No!" Wubslin screamed. He threw the restraining straps off, leapt across toward Horza and dived at the controls. Horza tried

to fend the

bulky engineer off, but failed. The controls were wrenched from his hands, and the view on the main screen tipped

and swirled, pointing the

nose of the speeding ship away from the black square of the GSV exit, away from the huge cloud of

airborne people, and toward the cliff of

brightly lit Mainbay entrances. Horza clouted Wubslin across the head with his arm,

sending the man falling to the floor, stunned. He grabbed

the controls back from the relaxing fingers of the engineer, but

it was too late to turn away. Horza steadied and aimed. The

Clear Air

Turbulence

darted for an open Mainbay; it flashed through the open entrance and swept over the skeleton of a starship being rebuilt

in the bay,

the light from the

CAT

’s motors starting fires, singeing hair, smoldering clothes and blinding unprotected eyes.

Horza saw Wubslin lying unconscious on the floor out of the corner of his eye, rocking gently as the

CAT

careered through the half-kilometer

length of Mainbay. The doors to the next bay were open, and the next and the next. They

were flying through a twokilometer tunnel, racing over

the repair and docking facilities of one of Evanauth’s displaced shipbuilders.

Horza didn’t know what was at the far end, but he could see that

before they got there they would have to fly over the top

of a large spaceship which almost filled the third bay along. Horza vectored the fusion

fire ahead so that they started to

slow. Twin beams of fire flashed on either side of the main screen as the fusion power kicked forward.

Wubslin’s unrestrained

body slid forward on the floor of the bridge, wedging under the console and his own seat. Horza lifted the

CAT

’s nose

as the blunt snout of the parked spacecraft sitting in the bay ahead approached.

The

Clear Air Turbulence

zoomed toward the ceiling of the Mainbay, flashed between it and the top surface of the ship, then fell on the

other side

and, although still slowing, shot through the final Mainbay and into another corridor of free air space. It was too narrow.

Horza dived

the craft again, saw the floor coming up and fired the lasers. The

CAT

burst through a rising cloud of glowing wreckage, bumping and shaking,

Wubslin’s squat frame sliding out from under the console

and floating back up toward the rear door of the bridge.

At first Horza thought they were out at last, but they weren’t; they were in what the Culture called a General bay.

The

CAT

fell once more, then leveled out again. It was in a space which seemed even larger than the main interior of the GSV. It

was flying

through the bay they had stored the Megaship in: the same Megaship Horza had seen on the screen earlier being lifted

out of the water by a