Kendrick was half tempted to try the thing then and there, but deferred the impulse. "What are the round buttons for?" he inquired instead. Marjorie didn't know, but thought they were probably an emergency pair, in case something went wrong with the square ones. In any event, nothing happened when you pushed them. Kendrick pushed one, just to see. It was true. Nothing happened--but he seemed to sense a faint, peculiar vibration and a wave of giddiness swept over him. On pushing the other, which released the first, it stopped. * * * * * He handed the device back to Marjorie. "There's your bracelet. Now, if I can just get one like it, I think we'll get down to earth all right." "Oh, Mr. Kendrick!" Her eyes lit up eagerly. "Then you've thought of a way?" "Not exactly. I think I've discovered their own way. I can't be certain, but I'm willing to gamble on it, if you are." "Then you--you think those round buttons are connected with the escalator rays?" "Exactly! I think they control individual descent and ascent, just as the square ones control individual visibility and invisibility. At any rate, it's the hunch I'm going to act on right now, if you're with me." "Oh, I'm with, you!" she breathed. "Anything, death almost, would be preferable to this." "Then stand by, invisible. I'm going to get one of my jailors in here and relieve him of his wrist-watch." Marjorie touched that little square button on her own. She instantly became invisible. Kendrick touched a button too, a button he had noticed beside the door. As he had supposed, it brought one of the Vadans. Shutting the door quietly, he seized the fellow before he could move his hand to his wrist. Thwarted in his attempt to vanish from sight, the diminutive guard attempted an outcry. But Kendrick promptly throttled him. * * * * * Marjorie had reappeared by now and together they bound him to a chair with a gilded cord torn from the drapery. Removing the precious mechanism from his wrist, Kendrick slipped it on his own. "Now let's go!" he said, pressing the protruding square button of the device. "We haven't a minute to--my golly, what a peculiar sensation!" "It is rather odd, isn't it?" she laughed, pressing her own and joining him in that invisible realm. "Feels like a combination electric massage and cold shower! Where are you, anyway? I can't see you." "Of course you can't!" came an unseen tinkle. "Here!" He felt her brush him. "Better hold hands," he suggested, then gave an invisible flush he was glad she couldn't see. "All right. A good idea." Her delicate hand came into his, soft, warm. Heart vibrating even faster than his body, his whole being a-quiver with a strange exaltation, Kendrick opened the door, and they left the apartment. * * * * * The next half-hour was the tensest either of then had ever experienced. Every foot of the way was fraught with peril.