"If there were any one around, they would certainly see Ab," reasoned Billie, "and would make some noise about it. I guess it's safe to go in."
He crawled around to the door and entered. There were the tracks of the horses, but the horses had disappeared as completely as though they had been swallowed up.
Billie called softly to Ab, who did not see fit to obey until he waved his whip. Then the animal sprang lightly to the ground. Billie showed him the tracks.
"Where do you suppose they went?" he asked.
Ab blinked his eyes and, for the first time since Billie had become acquainted with him, made a noise in his throat, much like the voice of a child.
Billie smiled in spite of himself.
"I'm glad you've decided to become sociable," he said, "What do you make of this? You look as though you could think."
Ab blinked his eyes stupidly and then suddenly became alert as though listening.
"What is it?" asked Billie, impressed by the ape's attitude.
For a reply Ab sprang through the window and made straight for the structure in the middle of the quarry. In another instant he was on the roof.