“But where are we?  What happened?  My head is dizzy—­I don’t know—­”

I gripped his hand.

“And no wonder.  ’Tis hardly an every-day occurrence to ride an underground river several miles under the Andes.  Above us a mountain four miles high, beneath us a bottomless lake, round us darkness.  Not a very cheerful prospect, Hal; but, thank Heaven, we take it together!  It is a grave—­ours and hers.  I guess Desiree knew what she was talking about.”

There came a cry from Harry’s lips—­a cry of painful memory: 

“Desiree!  I had forgotten, Desiree!”

“She is probably better off than we are,” I assured him.

I felt his gaze—­I could not see it—­and I continued: 

“We may as well meet the thing squarely like men.  Pull yourself together, Harry; as for Desiree, let us hope that she is dead.  It’s the best thing that could happen to her.”

“Then we are—­no, it isn’t possible.”

“Harry boy, we’re buried alive!  There!  That’s the worst of it.  Anything better than that is velvet.”

“But there must be a way out, Paul!  And Desiree—­Desiree—­”

His voice faltered.  I clapped him roughly on the shoulder.

“Keep your nerve.  As for a way out—­at the rate that stream descends it must have carried us thousands of feet beneath the mountain.  There is probably a mile of solid rock between us and the sunshine.  You felt the strength of that current; you might as well try to swim up Niagara.”

“But there must be an outlet at the other end.”

“Yes, and most probably forty or fifty miles away—­that’s the distance to the western slope.  Besides, how can we find it?  And there may be none.  The water is most probably gradually absorbed by the porous formation of the rocks, and that is what causes this lake.”

“But why isn’t it known?  Felipe said that the cave had been explored.  Why didn’t they discover the stream?”

Well, it was better to talk of that than nothing; at least, it kept Harry from his childish cries for Desiree.  So I explained that the precipice over which we had fallen was presumably of recent origin.

Geologically the Andes are yet in a chaotic and formative condition; huge slides of Silurian slates and diorite are of frequent occurrence.  A ridge of one of these softer stones had most probably been encased in the surrounding granite for many centuries; then, loosened by water or by time, had crumbled and slid into the stream below.

“And,” I finished, “we followed it.”

“Then we may find another,” said Harry hopefully.

I agreed that it was possible.  Then he burst out: 

“In the name of Heaven, don’t be so cool!  We can’t get out till we try.  Come!  And who knows—­we may find Desiree.”

Then I decided it was best to tell him.  Evidently the thought had not entered his mind, and it was best for him to realize the worst.  I gripped his hand tighter as I said: