“I don’t like the idea of crossing that river any more,” said Bob with a frown. “But I would like to go over to the secret cavern again tomorrow.”
“What for?” demanded Joe.
“I have two good reasons,” his friend answered. “First, I would like to take some movies of the place. And the other one is that I’d like to make a detailed map to give to Dr. Rust and the other archæologists. They’ll appreciate it, all right. Be tickled to death to know that we found all those Inca remains.”
The next morning they did as Bob wished and once more swung themselves across the boiling rapids, coming to the opposite side safely.
Motion pictures of the secret cavern and its contents were taken, and then a reliable map was made of the region, including the exact location of the mysterious buttons that moved the large stone doors.
Although Bob was assisted by his friends, he did not have everything completed until noon.
With one last look at the mountain of secrets, the three turned and retraced their footsteps to the river.
“Last time across,” said Joe with a sigh of relief. From the start he had feared the dangerous swing from the cable.
No harm befell them, however, and they reached the other side ready to start the journey to Pasaje, where Karl Sutman would be waiting with his airplane.
“Good old Karl,” said Bob affectionately. “It will be fine to see him again. And Dad and the others. I hope they’re all right.”