It seemed probable that when the geyser water shot up past the horizontal tunnel, its force was so great that no water at all entered. He redoubled his efforts to widen his swing.
Then his feet scraped on the floor, and in a second he had alighted there. He still hung stoutly to his line, however, for the tunnel sloped down sharply enough, and was slippery enough, to prohibit the maintenance of footing unaided.
The music which issued from the depths of that stunningly mysterious passage swelled to a crescendo—and stopped. Kirby clung there to his precarious perch, his feet slipping on the glass under them with every move he made, and feelings stirred in his heart which had never been there before.
Then, as silence reigned where the music had been, something prompted him to look up. The next instant he stifled a cry.
With widening eyes he saw the flash of a white arm and the gleam of a knife hovering over the spot where his taut rope passed out of the geyser opening into the sunshine of the outer world. Again he stifled a cry. For crying out would do no good. While the suppressed sound was still on his lips, the knife flickered.
Then Kirby was shooting downward, the severed line whipping out after him. The first plunge flung him off his feet. A long swoop which he took on his back dizzied him. But as the fall continued, he was able to slow it a little by bracing arms and legs against the tunnel walls.
“Holy Jeehosophat!” he gurgled.
But there seemed to be no particular danger. The slide was as smooth as most of the chutes he had ever encountered at summer swimming pools. If ever the confounded spiral passage came to an end, he might find that he was still all right. As seconds passed and he fell and fell, it seemed that he was bound for the center of the earth. It seemed that—