"Keep trying," Forrester ordered.

"Aye, aye, sir."

The captain turned to Lawton. "Suppose we call it a bubble. Why are we suspended like this, immovably? Your rocket leads shot up, and the plumb line dropped one hundred feet. Why should the ship itself remain stationary?"

Lawton said: "The bubble must possess sufficient internal equilibrium to keep a big, heavy body suspended at its core. In other words, we must be suspended at the hub of converging energy lines."

"You mean we're surrounded by an electromagnetic field?"

Lawton frowned. "Not necessarily, sir. I'm simply pointing out that there must be an energy tug of _some_ sort involved. Otherwise the ship would be resting on the inner surface of the bubble."

Forrester nodded grimly. "We should be thankful, I suppose, that we can move about inside the ship. Dave, do you think a man could descend to the inner surface?"

"I've no doubt that a man could, sir. Shall I let myself down?"

"Absolutely not. Damn it, Dave, I need your energies inside the ship. I could wish for a less impulsive first officer, but a man in my predicament can't be choosy."

"Then what _are_ your orders, sir?"

"Orders? Do I have to order you to think? Is working something out for yourself such a strain? We're drifting straight toward the Atlantic Ocean. What do you propose to do about that?"

"I expect I'll have to do my best, sir."

Lawton's "best" conflicted dynamically with the captain's orders. Ten minutes later he was descending, hand over hand, on a swaying emergency ladder.

"Tough-fibered Davie goes down to look around," he grumbled.

He was conscious that he was flirting with danger. The air outside was breathable, but would the diffuse, unorthodox gases injure his lungs? He didn't know, couldn't be sure. But he had to admit that he felt all right _so far_. He was seventy feet below the ship and not at all dizzy. When he looked down he could see the purple domed summits of mountains between gaps in the fleecy cloud blanket.

He couldn't see the Atlantic Ocean--yet. He descended the last thirty feet with mounting confidence. At the end of the ladder he braced himself and let go.

He fell about six feet, landing on his rump on a spongy surface that bounced him back and forth. He was vaguely incredulous when he found himself sitting in the sky staring through his spread legs at clouds and mountains.

He took a deep breath. It struck him that the sensation of falling could be present without movement downward through space. He was beginning to experience such a sensation. His stomach twisted and his brain spun.

He was suddenly sorry he had tried this. It was so damnably unnerving he was afraid of losing all emotional control. He stared up, his eyes squinting against the sun. Far above him the gleaming, wedge-shaped bulk of the Perseus loomed colossally, blocking out a fifth of the sky.

Lowering his right hand he ran his fingers over the invisible surface beneath him. The surface felt rubbery, moist.

He got swayingly to his feet and made a perilous attempt to walk through the sky.