"Professor!" he yelled excitedly. "Sue! Come here! The sphere's coming back!"
There was no doubt about it. The pin-point of light was growing each second, with the flame of the descending exhausts. Guinness and his daughter ran from the tunnel, and, guided by Phil's excited ejaculations, hurried to his side. Their eyes confirmed what his had seen. The earth-borer was coming down!
"But," Guinness said bewilderedly, "those rockets were enough to lift him!"
This was a mystery. Even though ten rockets were on—ten tiny spots of orange flame—the sphere came down swiftly. The same force which some time before had lifted it slowly up was now insufficient. The roar of the tubes rose rapidly. "Get back!" Phil ordered, remembering the danger, and they all retreated to the mouth of the tunnel, ready to peep cautiously around the edge. Holmes' jaws were locked tight with grim resolution. Quade was coming back! he told himself exultantly. This time he must not go up alone! This time—!
But his half-formed resolutions were idle. He could not know what frightful thing was bringing Quade down—what frightful experience was in store for them all....
CHAPTER IV
Spawn of the Cavern
n a crescendo of noise that stunned their ears, the earth-borer came down. Tongues of fire flared from the hole, speared to the ground and were deflected upward, cradling the metal ball in a wave of flame. Through this fiery curtain the machine slowly lowered to the floor, where a shower of sparks spattered out, blinding the eyes of the watchers with their brilliance. For a full minute the orange-glowing sphere lay there, quivering from the vibration; then the exhausts died and the wave of flame wavered and sank into nothingness. While their ear-drums continued the thunder, the three stared at the borer, not daring to approach, yet striving to solve the mystery of why it had sunk despite the up-thrust of ten rocket tubes.
As their eyes again became accustomed to the familiar phosphorescent illumination, pallid and cold after the fierce orange flame, they saw why—and their eyes went wide with surprise and horror.