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.
gain 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 up against something we haven't dared speak of to each other. Don't tell me that it's just men we've got to meet—"