t it a beauty?" murmured Stanley. "It ought to be," he added. "It
cost me eighty-six thousand to make it in my own glass factory. Eleven
castings before this one came along that was reasonably free of flaws.
Twenty-two feet six inches over all, walls five feet thick, new formula
unbreakable glass, four men working a month to grind the lid into place,
tolerance limits plus or minus zero."

He slapped the Professor's shoulders. "Let's go in and look over the
apparatus."

* * * * *

To accommodate the huge ball a well had been constructed in the Rosa's
hold. This brought the deck we were standing on up to within six feet of
the top ring, above which was rigged a chain hoist for lifting the
ponderous lid.

The hoist was revolved, the conical top was swung free, and we clambered
into our unique diving shell.

The tall cylinders were revealed as great flasks of compressed air. The
indeterminate thing beside the searchlight turned out to be a hand pump,
geared to work against heavy pressure. From the suction chamber of this
three tubes extended.

"We inhale the air of the chamber," the Professor explained to me, "and
exhale through the tubes into the pump cylinder. Breathe in through the
nose and out through the mouth. The pump piston is forced down by this
geared handle, sending the used air out of the shell through this
sixteenth-inch hole. A ball check valve keeps the water from squirting
in when the exhaust pressure is released."

He pointed to a telegraphic key which completed a circuit from the
batteries in the bottom of the ball to a thread of copper cast through
the lid.

"That's your plaything, Martin. You are to raise or lower us by pressing
that key. It controls the donkey engine electrically, so that we guide
our own destinies though we are a mile beneath our power plant. Stanley
works the pump. I direct the searchlight, write down notes, and, I
sincerely hope, take snapshots of deep sea life."

For a moment my part of the labor seemed so easy as to be unfair. Merely
to sit there and punch a little key at raising and lowering time! But as
I thought it over it began to appear more difficult.

The _Rosa_ could not anchor, of course, in a mile of water. We would
drift helplessly. If we approached an undersea cliff I must raise us at
once to prevent us being smashed against it. And if the cliff were too
lofty to be cleared in time....

I mentioned this to the Professor.

"