t.

"Let's have a look at that invisibility affair," he said.

She removed it from her wrist, handed it to him. Somewhat in awe, he
examined it.

* * * * *

The mechanism portion, which was linked in a strap of elastic metal,
resembled only superficially a watch, he now saw. Rather it had the
appearance of some delicate electric switch. Rectangular in shape, it
was divided into two halves by a band of white crystal. In each of
these halves were two little buttons of the same material, those on
one side round, on the other square.

"Which buttons control the invisibility?" he asked.

"The square ones," she replied. "One's pushed in now, you see. If you
should push the other, the first would come out--and you'd pass out of
the picture, so to speak."

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 d