On the cover, embedded in the silver, flashed and winked in the firelight, three magnificent gems, red, blue, green!

“Let me look at that a minute. Jack,” exclaimed Professor Chadwick in sharp, excited tones.

He took the box from his son, and an instant later his head and Mr. Jesson’s were close together over the rifled silver casket.

“Well, gentlemen?” said Ned after a while.

“Well,” echoed Professor Chadwick, “we have made a most astounding discovery. These gems which Jack discovered,—for they are genuine, there’s not a doubt of it,—must have been covered with wax of some sort. The heat of the fire, when the box fell into it, melted this substance, and—well, here are three gems worth, conservatively, two hundred and fifty thousand dollars; probably a great deal more.”

The listeners looked at him in amazement.

“But what were the gems that Herrera took out of the casket, then?” demanded Jack, when he found his voice.

“Imitations, undoubtedly,” was the reply of Mr. Jesson. “The tribe that owned the genuine stones adopted this cunning means of concealing the real ones by coating them with wax of some sort. Then they placed inferior gems, or cunning imitations, within the box, trusting to the cupidity of any one who stole them not to investigate further.”

And so it proved afterward. The stones, which the strange and seemingly trivial accident had revealed, turned out to be as fine specimens of their respective kinds as there are in existence. They were appraised at six hundred and eighty thousand dollars, but cryptic carvings on the back of them made them of infinitely more value to science as specimens of the treasures of a vanished race.

Despite their keen excitement over the discovery that, after all, Herrera had not decamped with the precious stones, the adventurers slept soundly and peacefully that night.