sense of extreme physical nausea overcame him. He reeled, then managed to steady himself. He, too, was invisible to his own eyes. Involuntarily he cried out. No sound came from his lips. He stood there, invisible in an invisible, soundless void.
For what seemed an unending period he occupied himself with endeavoring to obtain the sense of balance. Then, with a great effort, he managed to loosen the cords that bound his right arm to his side. A mighty wrench, and he had slipped them up above his elbow. His right lower arm was free.
He extended it cautiously, and his hand encountered a railing. Instantly he felt more at ease. He began moving slowly around in a widening circle, and discovered that the platform was enclosed. The further side was, however, open, and he began sliding forward, foot by foot, to locate himself. Once his foot slipped over the edge, and he drew back hastily. He felt on the other side, and discovered that he was upon what seemed a plank walk, perhaps a hundred and fifty feet above the ground, with no rail on either side, and some six feet wide.
Very cautiously he shuffled his way along it. It was solid enough, although invisible, but more than once Dick walked perilously close to one edge or the other. At length he went down on his hands and knees, and proceeded, crawling, until his movements were arrested by what was unmistakably a door.
The plank bridge, then, connected the top stories of two buildings, but what the second was, there was no means of knowing. The door was barred on the other side, and did not yield an iota to Dick's cautious pressure. Dick felt the frame. Beyond was glass, reinforced with iron on the outside, the latter metal forming a sort of lattice work. Cautiously Dick began to crawl up the rounded dome.
oot by foot he made his way, clinging to the iron bars, until he felt that he had reached the point of the dome's maximum convexity. He wedged his feet against a bar and rested. Only now was it brought home to him that it would be impossible for him to find his way back to the plank.