"Well, seems to me there's plenty of mystery about everything that's happened today," said Dorothy. "What are we going to do now, Wizard?"
"Explore our prison," answered the little man promptly.
Dorothy looked about her. They were entirely surrounded by the solid stone walls of the cavern, which was about one-hundred feet square. She could detect no sign of the door by which they had entered.
"Look, Wizard," Dorothy exclaimed. "See how the light shines from one small point in the far end of the cavern?"
"Yes," agreed the Wizard, "it's almost as if someone had built a powerful flashlight into the stone wall. Come, let's examine the light more closely."
The two walked to the opposite side of the cavern and found that, as Dorothy had observed, the flood of light originated from one small point. This point was a circular bit of stone, round and polished, and no larger than a small button.
"Why," exclaimed Dorothy, "it looks 'zactly like the button of an electric light switch! Wonder what would happen if I pressed it?"
Impulsively Dorothy reached out and pressed the button of rock with her finger. In the deep silence that filled the cave, the two adventurers detected a far-away humming sound, like the whirring of wheels in motion. As Dorothy and the Wizard listened, the sound grew louder.
"What do you suppose it is?" whispered Dorothy.
"I haven't the faintest idea," said the Wizard, "but I don't think we'll have to wait long to find out."