onds. It seemed unlikely now that it had let go as a result
of defective material. He stepped to the flange that connected it with
the stern bulkhead.

The tube, inactivated immediately after the blowout, was cold. He looked
where his suspicions directed.... The aperture control valve had been
readjusted! It had been displaced a full fifteen degrees on the topside
of optimum power! A cunning setting--one that would trap and concentrate
enough residual di-ions at normal power output to cut loose somewhere
between the fifth and tenth jump.

He thought, too, of his transmitter that hadn't been powerful enough to
reach farther than a couple of jumps since he had left spaceport. When,
he asked himself, had Altman's radioman worked on it?

* * * * *

After he slammed the hatch and dogged it, he leaned against the thick
metal for a long while. The _clack-clack_ overhead was somewhat
pacified. But it wouldn't remain that way long. He quelled the fear
sensations that were racing through him and tried to think.

How long? How long had it been since Jim left? He was three jumps away a
few hours ago--or was it longer than that?--and he still had seven to go
or was it six? Had it been just a few hours ago, or was it days? He had
slept some--twice, he believed--since then. But for how long? And if the
tow ships did make it back in time, would they have spare rods?

He gave it up as a hopeless speculation and started back up the
passageway, shoulders drooping.

_Karoom!_

The new sound reverberated through the agonized vessel and the bulkheads
of the passageway shuddered in fanatic sympathy with it.

The deck shifted crazily beneath his feet and a port beam--the bulkhead
and the rest of the ship following it--swung over to crash into his
shoulder.

A stabbing pain shot up his arm as he slid down the tilting wall and
landed in the right angle between the deck and the bulkhead.

Massaging the torn ligament in his arm, he sat up and swayed dizzily in
resonance with the pendulum-like motion of the vessel. Then he struggled
to his feet and stood upright--one foot planted at an angle against the
deck and the other against the port bulkhead. Overhead was the
corresponding juncture made by the ceiling plate and the starboard
bulkhead.

Nausea welled as he tried to adjust to the new, perverted up and down
references. He didn't have to wonder what had happened. The starboard
gray coil that ran under