alf a mile short of the summit he fell for
the last time. He tried to get up, failed, and tried to crawl. He failed
at that, too, and collapsed face down in the rocky soil.

Humbolt went to him and said between his own labored intakes of breath,
"Wait, Dan--I'll go on--bring you back water."

Barber raised himself with a great effort and looked up. "No use," he
said. "My heart--too much----"

He fell forward again and that time he was very still, his desperate
panting no more.

* * * * *

It seemed to Humbolt that it was half a lifetime later that he finally
reached the spring and the cold, clear water. He drank, the most
ecstatic pleasure he had ever experienced in his life. Then the pleasure
drained away as he seemed to see Dan Barber trying to smile and seemed
to hear him say, "It would be hell--to have to die--so thirsty like
this."

He rested for two days before he was in condition to continue on his
way. He reached the plateau and saw that the woods goats had been
migrating south for some time. On the second morning he climbed up a
gentle roll in the plain and met three unicorns face to face.

They charged at once, squealing with anticipation. Had he been equipped
with an ordinary bow he would have been killed within seconds. But the
automatic crossbow poured a rain of arrows into the faces of the
unicorns that caused them to swing aside in pain and enraged
astonishment. The moment they had swung enough to expose the area just
behind their heads the arrows became fatal.

One unicorn escaped, three arrows bristling in its face. It watched him
from a distance for a little while, squealing and shaking its head in
baffled fury. Then it turned and disappeared over a swell in the plain,
running like a deer.

He resumed his southward march, hurrying faster than before. The unicorn
had headed north and that could be for but one purpose: to bring enough
reinforcements to finish the job.

* * * * *

He reached the caves at night. No one was up but George Ord, working
late in his combination workshop-laboratory.

George looked up at the sound of his entrance and saw that he was alone.
"So Dan didn't make it?" he asked.

"The chasm got him," he answered. And then, wearily, "The chasm--we
found the damned thing."

"The red stratum----"

"It was only iron stains."

"I made a little pilot smelter while you were gone," George said. "I was
hoping t