But they were Spanish, and they failed to make them out.

Beneath them was a hand with the index finger pointing to a passage at their right.

“This must be the way out, Martin,” said Dick. “Come on; we will follow this passage.”

“Good enough!” returned the Yankee, and they at once set out.

But they soon found that the passage went downward instead of on a level, as the one they had before traversed.

However, they did not turn back; the hand upon the rock pointed that way, and both were anxious to see what it meant.

Down they went for fully fifteen minutes, and then they observed a bright light ahead of them.

But it was not the light of day that they saw; it was a sort of pale, greenish tint.

In a few minutes they emerged into a vast chamber of a conical shape, which seemed to be lighted by electricity, though where the seat of the light was located they could not tell.

In the center of the conical-shaped cavern was a pool of crystal water, from which a sparkling fountain shot upward, sending a myriad of glistening drops scatteringly through space.