endrick was thinking fast.
"There's just a chance," he said. "It all depends upon how wide the zone of these escalator rays is, and whether we can tune in on them. At least, I can probably answer the latter question."
Pushing the protrudent round button on his mysterious bracelet as he spoke, he leaned over the edge of the trap-door and awaited results.
They were not long in coming. The vibration he was already under from the invisibility rays seemed to double. Alternate waves of giddiness and depression, of push and pull, swept over him.
A minute of it was enough. He pressed the round button that now protruded, ending this influence, and faced Marjorie, stating:
"I'm positive now that these things control descent and ascent. As nearly as I can figure, the rays work on the principle of an endless belt. If you're up here, you get carried down, and vice versa. As to how wide the belt is, and whether you can move sideways on it, remains to be seen. Anyway, I'm going to take a chance. I'll go first. If my guess is wrong, you—well, needn't follow."
"No, I'm going with you!" she declared resolutely. "We've come this far together. I shan't be left alone now. Let's go!"
And again her soft, warm hand was in his.