Two pillars of intense light, a ray of crimson flame and another of deeply violet radiance, beat straight down from a complicated array of enormous, oddly shaped electron tubes, of mirrors and lenses and prisms, of coils and whirling disks, which reached almost to the roof. Upright, a yard in diameter and almost a yard apart, the strange columns of light were sharp-edged as two transparent cylinders filled with liquid light of ruby and of amethyst. Each ray poured down upon a circular platform of glass or polished crystal. Hanging between those motionless cylinders of red and violet light was a strange-looking, greenish globe. A round ball, nearly a yard in diameter, hung between the rays, almost touching them. Its surface was oddly splotched with darker and lighter areas. It was spinning steadily, at a low rate of speed. Larry did not see what held it up; it seemed hanging free, several feet above the crystal platforms. Reluctantly he withdrew his eyes from the mysterious sphere and looked about the room once more. No, the laboratory was vacant of human occupants. No one was hidden among the benches that were cluttered with beakers and test tubes and stills, or among the dynamos and transformers in the other end of the room. A confusion of questions beat through Larry's brain. What danger could be haunting this quiet laboratory? Was this the blood of Agnes Sterling or the scientist who employed her that was now clotting on the floor? What terrific force had crumpled up the revolver? What had become of Agnes and Dr. Whiting? And of whatever had attacked them? Had Agnes called him after the attack, or before? * * * * * Despite himself, his attention was drawn back to the little globe spinning so regularly, floating in the air between the pillars of red and violet flame. Floating alone, like a little world in space, without a visible support, it might be held up by magnetic attraction, he thought. A tiny planet! His mind quickened at the idea, and he half forgot the weird mystery gathering about him. He stepped nearer the sphere. It was curiously like a miniature world. The irregular bluish areas would be seas; the green and the brown spaces land. In some parts, the surface appeared mistily obscured--perhaps, by masses of cloud. Larry saw an odd-looking lamp, set perhaps ten feet behind the slowly spinning, floating ball, throwing upon it a bright ray of vividly blue light. Half the strange sphere was brilliantly illuminated by it; the rest was in comparative darkness. That blue lamp, it came to Larry, lit the sphere as the sun lights the earth. "Nonsense!" he muttered. "It's impossible!"