rs. That makes stable flight possible. It's all more or less
like what we've just seen, and I don't suppose you want to miss the
dance--anyway, a lot of people want to dance with you."

"Wouldn't you just as soon show me through the lower half as dance?"

"Rather, lots!"

"So would I. I can dance any time, and I want to see everything.
Let's go!"

Down they went, past battery after battery of accumulators; climbing
over and around the ever-increasing number of huge steel girders and
bracers; through mazes of heavily insulated wiring and conduits; past
mass after mass of automatic machinery which Stevens explained to his
eager listener. They inspected one of the great driving projectors,
which, built rigidly parallel to the axis of the ship and held immovably
in place by enormous trusses of steel, revealed neither to the eye nor
to the ear any sign of the terrific force it was exerting. Still lower
they went, until the girl had been shown everything, even down to the
bottom ultra-lights and stern braces.

"Tired?" Stevens asked, as the inspection was completed.

"Not very. It's been quite a climb, but I've had a wonderful time."

"So have I," he declared, positively. "I know what--we'll crawl up into
one of these stern lifeboats and make us a cup of coffee before we climb
back. With me?"

"'Way ahead of you!" Nadia accepted the invitation enthusiastically,
and they made their way to the nearest of the miniature space-cruisers.
Here, although no emergency had been encountered in all the four years
of the vessel's life, they found everything in readiness, and the two
soon had prepared and eaten a hearty luncheon.

"Well, I can't think of any more excuses for monopolizing you, Miss
Newton, so I suppose I'll have to take you back. Believe me, I've
enjoyed this more than you can realize--I've...."

He broke off and listened, every nerve taut. "What was that?" he
exclaimed.

"What was what? I didn't hear anything?"

"Something screwy somewhere! I felt a vibration, and anything that'd
make this mountain of steel even quiver must have given us one
gosh-awful nudge. There's another!"

The girl, painfully tense, felt only a barely perceptible tremor, but
the computer, knowing far better than she the inconceivable strength and
mass of that enormous structure of solidly braced hardened steel, sprang
into action. Leaping to the small dirigible look-out plate, he turned on
the power and swung it upward.

*