“Ralph,” he said hoarsely, as he drew himself back, “hold this lantern and get down out of my way.  I must cover this up, quick.”  And seizing the stone slab by the handle, he lifted it as if it had been a pot-lid, and let it down into its place.  “Now,” said he, “get down, and let us all go away from this place.  Those negroes may be back at any moment.”

When Ralph found that his sister had fainted, and that Mrs. Cliff did not know it, there was a little commotion at the foot of the mound.  But some water in a pool near by soon revived Edna, and in ten minutes the party was on the plateau outside the caverns.  The new moon was just beginning to peep over the rocks behind them, and the two ladies had seated themselves on the ground.  Ralph was pouring out question after question, to which nobody paid any attention, and Captain Horn, his hands thrust into his pockets, walked backward and forward, his face flushed and his breath coming heavily, and, with his eyes upon the ground, he seemed to think himself entirely alone among those desolate crags.

“Can any of you tell me what it means?” cried Mrs. Cliff.  “Edna, do you understand it?  Tell me quickly, some of you!”

“I believe I know what it means,” said Edna, her voice trembling as she spoke.  “I thought I knew as soon as I heard of the mound covered up by the lake, but I did not dare to say anything, because if my opinion should be correct it would be so wonderful, so astounding, my mind could hardly take hold of it.”

“But what is it?” cried Mrs. Cliff and Ralph, almost in one breath.

“I scarcely know what to say,” said Edna, “my mind is in such a whirl about it, but I will tell you something of what I have read of the ancient history of Peru, and then you will understand my fancies about this stone mound.  When the Spaniards, under Pizarro, came to this country, their main object, as we all know, was booty.  They especially wished to get hold of the wonderful treasures of the Incas, the ancient rulers of Peru.  This was the reason of almost all the cruelties and wickedness of the invaders.  The Incas tried various ways of preserving their treasures from the clutch of the Spaniards, and I have read of a tradition that they drained a lake, probably near Cuzco, the ancient capital, and made a strong cellar, or mound, at the bottom of it in which to hide their gold.  They then let the water in again, and the tradition also says that this mound has never been discovered.”

“Do you believe,” cried the captain, “that the mound back there in the cavern is the place where the Incas stored their gold?”

“I do not believe it is the place I read about,” said Miss Markham, “for that, as I said, must have been near Cuzco.  But there is no reason why there should not have been other places of concealment.  This was far away from the capital, but that would make the treasure so much the safer.  The Spaniards would never have thought of going to such a lonely, deserted place as this, and the Incas would not have spared any time or trouble necessary to securely hide their treasures.”