This time, however, the reaction was instantaneous. A fierce tongue of green flame licked out and seized the flying plane in mid-air. One wing and side panel were sliced off neatly and Siblin was thrown out violently, but he did not fall. Surrounded by a vibrant shell of energy, he was drawn rapidly toward the huge dome. The dome merged with the shell as it touched it, but the two did not coalesce. The shell passed smoothly through the dome, which as smoothly closed behind it. Siblin inside the shell, the shell inside the dome. XVII. Siblin never knew exactly what happened during those first few minutes, nor exactly how it happened. One minute, in his sturdy plane, he was setting up his "diversion" by directing a powerful beam of force upon the green dome of the invaders. Suddenly his rocket ship had been blasted apart and he had been hurled away from the madly spinning, gyrating wreckage. He had a confused recollection of sitting down violently upon something very hard, and perceived dully that he was lying asprawl upon the inside of a greenishly shimmering globe some twenty feet in diameter. Its substance had the hardness of chilled steel, yet it was almost perfectly transparent, seemingly composed of cold green flame, pale almost to invisibility. He also observed, in an incurious, foggy fashion, that the great dome was rushing toward him at an appalling pace. He soon recovered from his shock, however, and perceived that the peculiar ball in which he was imprisoned was a shell of force, of formula and pattern entirely different from anything known to the scientists of Valeron. Keenly alive and interested now, he noted with high appreciation exactly how the wall of force that was the dome merged with, made way for, and closed smoothly behind the relatively tiny globe. Inside the dome he stared around him, amazed and not a little awed. Upon the ground, the center of that immense hemisphere, lay a featureless, football-shaped structure which must be the vessel of the invaders. Surrounding it there were massed machines and engineering structures of unmistakable form and purpose; drills, derricks, shaft heads, skips, hoists, and other equipment for boring and mining. From the lining of the huge dome there radiated a strong, lurid, yellowish-green light which intensified to positive ghastliness the natural color of the gaseous chlorin which replaced the familiar air in that walled-off volume so calmly appropriated to their own use by the Outlanders.