nishment," groaned the
inventor, covering his eyes with his hands. "It was I who invented
this wretched boat!"

"But you didn't lose the wrench, or mislay it," broke in Eph Somers,
with the intention of consoling.

"Who _did_ mislay it?" pondered Captain Jack aloud. "If we could only
settle that point, it might start us on the right track to finding the
thing yet. For, of course, it's on board."

The certainty that the wrench must be _somewhere_ on the boat brought
all to their feet, though this time they rose slowly, almost painfully.

After a few minutes the search became listless. At Hal's suggestion,
made with a wan smile, each even searched through his own baggage.
Pantry and galley were patiently ransacked.

"I've heard of such things being lost before, in the simplest way, and
defying all search for a long time," mused Hal, aloud. "It may be the
same with that precious wrench. But the difference, this time, is that
we shan't be here long to wait for it to turn up unexpectedly."

Farnum dropped into a seat again, and that started the rest, until all
had taken seats. From one to another, dumb, moody looks were passed.
Each was wonderingly asking himself the same question that none would
have thought of framing in words. How much longer could the air last
in a pure enough condition to sustain six lives?

Eph Somers chuckled, absently, then looked up, startled and ashamed.
The others gazed at him, comprehendingly. Each knew that Eph was
thinking how idiotic it was for six human beings to sit, in perfect
health, waiting until the soiling of the air about them killed them all.
It was a terrible thought; Eph's mirth was of the hysterical kind.

Finally, after some minutes had passed, Jack Benson dragged himself
to his feet.

He was amazed, at first thought, to find out how every joint and muscle
in his body ached. He felt as weary as though he had been without
sleep for a month.

Then he understood. The dreadful lassitude was caused by the withdrawing
of the life-giving oxygen from the air. The oxygen was still there, but
combined with the carbon from lungs and blood to form carbonic acid gas,
which, in large quantities, is fatal to life.

When Jack moved about now, feeling, dully, as though a cane on which to
lean would be a great boon, the others got to their feet with evident
effort and joined in one more despairing search.

This hunt ended as the others had done, only more quickly. The onl