s there?" Smithy demanded. "What do you think that you'll find?"

"I don't know," was the reply.

"Then why--what the devil's the idea?"

"It's my job. They put it up to me, Erickson and his crowd. I've got
to go."

And nothing Smithy could say seemed able to reach Rawson and swerve
him from his single idea.

"You'll be safe on the road," Rawson told him, while he filled a
canteen with water in preparation for his own trip. "You can get to
the highway by morning."

Smithy did not trouble to reply. Was Rawson out of his mind? He could
not be sure. Certainly he had got an awful bump, but there were no
bones broken. However, it might be that he was still dazed--a crack on
the head might have done it.

But there was no use in further argument, he admitted to himself. Dean
was going to the crater again--there was no stopping him--but he was
not going alone; Smithy could see to that.

* * * * *

Again Rawson took the more difficult ascent. They went first to the
ghost town: the slope above Little Rhyolite would save weary miles.
But, once there, they knew that the route was not a place where they
would care to be in the night. The realization came when Smithy,
walking where they had been the day before, passing the sand dune
where the wind had been scouring, seized Rawson's arm.

"I thought so," he said softly. "I thought I saw something there the
other day, but the sand fell in and hid it. I didn't know the
old-timers went in for subways in Little Rhyolite."

And Rawson looked as did Smithy, in wondering amazement, at the
roughly round opening in the sand, a tunnel mouth, driven through the
shifting sands--a tunnel, if Rawson was any judge, lined with brown
glistening glass.

Understanding came quickly.

"The jet of flame!" he exclaimed half under his breath. "They melted
their way through; the sand turned to glass; they held it some way for
an instant while it hardened." He walked cautiously toward the dark
entrance and peered inside.

Darkness but for the nearer glinting reflections from walls that had
once been molten and dripping. The tunnel dipped down at a slight
angle, then straightened off horizontally. Rawson could have stood
upright in it with easily another two feet of headroom to spare.

"And that," said Smithy, "is how the dirty rats got over to the camp.
Like moles in their runway. No wonder they could pop up from nowhere.
But, Dean, old man, I'm thinkin' we're