It was not easy to frighten Burke, but now he trembled, and his back was chilled.  But he soon recovered sufficiently to do something, and going down to the floor of the cave, he picked up a piece of loose stone, and returning to the top of the mound, he looked carefully over the edge of the opening, and let the stone drop into the black hole beneath.  With all the powers of his brain he listened, and it seemed to him like half a minute before he heard a faint sound, far, far below.  At this moment he was worse frightened than he had ever been in his life.  He clambered down to the foot of the mound, and sat down on the floor.

“What in the name of all the devils does it mean?” said he; and he set himself to work to think about it, and found this a great deal harder labor than cutting stone.

“There was only one thing,” he said to himself, at last, “that they could have had that for.  The captain says that those ancient fellows put their gold there keep it from the Spaniards, and they must have rigged up this devilish contrivance to work if they found the Spaniards had got on the track of their treasure.  Even if the Spaniards had let off the water and gone to work to get the gold out, one of the Incas’ men in the corner of that other cave, which most likely was all shut up and not discoverable, would have got hold of that bar, given it a good pull, and let down all the gold, and what Spaniards might happen to be inside, to the very bottom of that black hole.  By George! it would have been a pretty trick!  The bottom of that mound is just like a funnel, and every stick of gold would have gone down.  But, what is more likely, they would have let it out before the Spaniards had a chance to open the top, and then, if the ancients had happened to lick the Spaniards, they could have got all that gold up again.  It might have taken ten or twenty years, but then, the ancients had all the time they wanted.”

After these reflections, Burke sat for a few moments, staring at the lantern.  “But, by George!” said he again, speaking aloud, though in low tones, “it makes my blood run cold to think of the captain working day after day, as hard as he could, right over that horrible trap-door.  Suppose he had moved the bolt in some way!  Suppose somebody outside had found that slab in the wall and had fooled with the bar!  Then, there is another thing.  Suppose, while they were living here, he or the boy had found that bar before he found the dome, and had pulled out the concern to see what it was!  Bless me! in that case we should all be as poor as rats!  Bat I must not stop here, or the next watch will be called before I get back.  But one thing I’ll do before I go.  I’ll put back that lid.  Somebody might find the dome in the dark, and tumble into it.  Why, if a wandering rat should make a slip, and go down into that black hole, it would be enough to make a fellow’s blood run cold if he knew of it.”

Without much trouble Burke replaced the lid, and then, without further delay, he left the caves.  As he hurried along the beach, he debated within himself whether or not he should tell Captain Horn what he had discovered.