The sphere was blind. The man inside could judge his course only by the feel. As the three who were deserted watched, hoping ardently that Quade would not be able to find the opening, the left side-rockets spouted lances of fire, and they knew he had discovered the way to maneuver the borer laterally. The new flames welded with the exhaust of the main tubes into a great fan-shaped tail, so brilliant and shot through with other colors that their eyes could not stand the sight, except in winks. The borer jerked to the right, but still it could not find the hole. Then the flames lessened for a moment, and the borer sank down, to rise again a moment later. Its ascent was so labored that Phil shouted to Professor Guinness: "Why so slow?" And the inventor told him that which he had not seen for the intolerable light. "Only half his rockets are on!" * * * * * This time the sphere was correctly aimed, however, and it roared straight into the hole. Immediately the fierce sound of the exhaust was muffled, and in a few seconds only the fiery plumage, shooting down from the ceiling, showed where the machine was. Then this disappeared, and the noise alone was left. Phil leaped forward, intending to stare up, but Guinness's yell halted him. "Not yet! He might still use the disintegrators!" For many minutes they waited, till the muffled exhaust had died to a drone. There was a puzzled expression on the professor's face as the three at last walked over and dared peer up into the hole. Far above, the splash of orange lit the walls of the tunnel. "That's funny!" the old man muttered. "He's only using half the rockets--about ten. I thought he'd turn them all on when he got into the hole, but he didn't. Either they were damaged in the fall, or Quade doesn't see fit to use them." "Half of them are enough," said Phil bitterly, and put his arm around the quiet girl standing next to him. Together, a silent little group, they watched the spot of orange die to a pin-point; watched it waver, twinkle, ever growing smaller.... And then it was gone. Gone! Back to the surface of the earth, to the normal world of reality. Only four miles above them--a small enough distance on the surface itself--and yet it might have been a million miles, so utterly were they barred from it.... * * * * * The same thought was in their minds, though none of them dared express it. They were thinking of the serene desert, and the cool wind, and the buttes and the high hills, placid in the moonlight. Of the hushed rise of the dawn, the first flush of the sun that was so achingly lovely on the desert. The sun they would never see again, buried in a lifeless world of gloom four miles within.... And buried alive--and not alive for long.... But that way lay madness. Phil Holmes drove the horrible thoughts from his brain and forced a smile to his face. "Well, that's that!" he said in a voice meant to be cheerful.