ppeared suddenly
on Earth.

"Good God, Dave. Do you suppose something has happened to space?"

Lawton raised his eyes with a shudder. "Not necessarily, sir. Something
has happened to _us_. We're floating through the sky in a huge,
invisible bubble of some sort, but we don't know whether it has anything
to do with space. It may be a meteorological phenomenon."

"You say we're floating?"

"We're floating slowly westward. The clouds beneath us have been
receding for fifteen or twenty minutes now."

"Phew!" muttered Forrester. "That means we've got to--"

He broke off abruptly. The Perseus' radio operator was standing in the
doorway, distress and indecision in his gaze. "Our reception is
extremely sporadic, sir," he announced. "We can pick up a few of the
stronger broadcasts, but our emergency signals haven't been answered."

"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