Even the breathing air of the “Pollard’s” interior could not be renewed without the wrench.  Though each strove to conceal his feelings from the others, grim horror soon had them all in its grip.

CHAPTER XVIII

THE LAST GASP OF DESPAIR

“I can’t realize it yet, or believe it.  It can’t be true,” shuddered David Pollard.

“We surely did,” asserted Captain Jack.

“Could you swear that you have seen the wrench since we sailed?” asked Jacob Farnum, white-faced but cool.

“I—­I can’t quite say as to that,” replied Benson, slowly.  “But I will swear that I remember having seen it just a few minutes before we started.”

“A few minutes—­only?” insisted the builder.

“Yes, sir.  I’m positive.”

“For that matter,” continued the builder, “there has been no one on board to-day save those who belong aboard.”

“No; no one but ourselves has been on the boat to-day.”

“None of us would throw it overboard, knowing how precious a tool it is,” declared Mr. Farnum, glancing about him bewildered.  “It was hardly possible to mislay such a thing by accident.  Where on earth can it be, then?”

Again all hands started to hunt.  Henderson was the first to sink to a seat as a sign that he gave up the search.  The others barely glanced at him, so intent were all on the hunt that meant their only chance for life.

Yet at last they all sat down, panting, perspiring.

“Good heavens!” quivered the inventor.  “We must soon begin to think of our very breath here.  We can’t exert ourselves as we have been doing.  Whoever moves now, let him remember that he is using up the very life of others in the act of breathing!”

All but devoid of hope, they all remained sitting.  At first they studied the floor, gloomily.  At last they looked up, to read each other’s faces.  No hope was to be seen in any countenance.

“Thank heaven the electric light doesn’t eat up air,” shuddered Hal Hastings, at last.  “It would be fearful to be alive—­conscious—­after it had become dark!”

“Don’t!” shivered David Pollard, convulsively.

“Come, come, old chap,” urged Farnum, laying a hand on his friend’s arm, “you are not going to lose your courage?”

“I feel as if I ought to bear the whole punishment,” 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.