could even stand up with
that weight of metal on and around him!"

"You're mistaken, Taylor," smiled Mercer. "That is not solid metal,
you see. And it is an aluminum alloy that is not nearly as heavy as it
looks. There are two walls, slightly over an inch apart, braced by
innumerable trusses. The fabric is nearly as strong as that much solid
metal, and infinitely lighter. They work all right, Taylor. I know,
because I've tried them."

"And this hump on the back?" I asked, walking around the odd, dangling
figures, hanging like bloated metal skeletons from their chains. I
had thought the bodies were perfect globes; I could see now that at
the rear there was a humplike excrescence across the shoulders.

"Air," explained Mercer. "There are two other tanks inside the
globular body. That shape was adopted, by the way, because a globe can
withstand more pressure than any other shape. And we may have to go
where pressures are high."

"And so," I said, "we don these things and stroll out into the
Atlantic looking for the girl and her friends?"

"Hardly. They're not quite the apparel for so long a stroll. You
haven't seen all the marvels yet. Come along!"

* * * * *

He led the way through the patio, beside the pool in which our strange
visitor from the depths had lived during her brief stay with us, and
out into the open again. As we neared the sea, I became aware, for the
first time, of a faint, muffled hammering sound, and I glanced at
Mercer inquiringly.

"Just a second," he smiled. "Then--there she is, Taylor!"

I stood still and stared. In a little cove, cradled in a cunning,
spidery structure of wood, a submarine rested upon the ways.

"Good Lord!" I exclaimed. "You're going into this right, Mercer!"

"Yes. Because I think it's immensely worth while. But come along and
let me show you the _Santa Maria_--named after the flagship of
Columbus' little fleet. Come on!"

Two men with army automatics strapped significantly to their belts
nodded courteously as we came up. They were the only men in sight, but
from the hammering going on inside there must have been quite a
sizeable crew busy in the interior. A couple of raw pine shacks, some
little distance away, provided quarters for, I judged, twenty or
thirty men.

"Had her shipped down in pieces," explained Mercer. "The boat that
brought it lay to off shore and we lightered the parts ashore. A
tremendous job. But she'll be ready fo