As he spoke old Goosal glided forward. He had remained behind them in the passage while they were trying to move the rock. Now he said something in Spanish.
"What does he mean?" asked Ned.
"He asks that he be allowed to try," translated Professor Bumper. "Sometimes, he says, there is a secret way of opening stone doors in these underground caves. Let him try."
Goosal seemed to be running his fingers lightly over the outer edge of the door. He was muttering to himself in his Indian tongue.
Suddenly he uttered an exclamation, and, as he did so, there was a noise from the door itself. It was a grinding, scraping sound, a rumble as though rocks were being rolled one against the other.
Then the astonished eyes of the adventurers saw the great stone door revolve on its axis and swing to one side, leaving a passage open through which they could pass. Goosal had discovered the hidden mechanism.
What lay before them?