d the cliffs! Ye spoke a true word,
sir--behoind!"

Bradley laughed--a rather sorry laugh, though. "You might as well call
our attention to the fact, sir," he said, "that science has indicated
that there is fresh water and vegetation on Mars."

"Not at all," I rejoined. "A U-boat isn't constructed to navigate
space, but it is designed to travel below the surface of the water."

"You'd be after sailin' into that blank pocket?" asked Olson.

"I would, Olson," I replied. "We haven't one chance for life in a
hundred thousand if we don't find food and water upon Caprona. This
water coming out of the cliff is not salt; but neither is it fit to
drink, though each of us has drunk. It is fair to assume that inland
the river is fed by pure streams, that there are fruits and herbs and
game. Shall we lie out here and die of thirst and starvation with a
land of plenty possibly only a few hundred yards away? We have the
means for navigating a subterranean river. Are we too cowardly to
utilize this means?"

"Be afther goin' to it," said Olson.

"I'm willing to see it through," agreed Bradley.

"Then under the bottom, wi' the best o' luck an' give 'em hell!" cried
a young fellow who had been in the trenches.

"To the diving-stations!" I commanded, and in less than a minute the
deck was deserted, the conning-tower covers had slammed to and the U-33
was submerging--possibly for the last time. I know that I had this
feeling, and I think that most of the others did.

As we went down, I sat in the tower with the searchlight projecting its
seemingly feeble rays ahead. We submerged very slowly and without
headway more than sufficient to keep her nose in the right direction,
and as we went down, I saw outlined ahead of us the black opening in
the great cliff. It was an opening that would have admitted a
half-dozen U-boats at one and the same time, roughly cylindrical in
contour--and dark as the pit of perdition.

As I gave the command which sent the U-33 slowly ahead, I could not but
feel a certain uncanny presentiment of evil. Where were we going?
What lay at the end of this great sewer? Had we bidden farewell
forever to the sunlight and life, or were there before us dangers even
greater than those which we now faced? I tried to keep my mind from
vain imagining by calling everything which I observed to the eager ears
below. I was the eyes of the whole company, and I did my best not to
fail them. We had advanced a