“The water must be of immense depth,” said Joe.
“In some cases it has been impossible to touch bottom, even with the longest lines and the most perfect sounding apparatus,” was the astonishing reply.
“But how does an island come to be in the middle of such a deep lake?” was what Mr. Tubbs wanted to know.
“What we call an island is probably the summit of another peak of the crater,” said the professor, “or it may have been formed, like those volcanic islands of which we have such a keen recollection, by the action of earth’s internal fires.”
The dirigible dropped lower. It was now almost directly above the lost city. It could be seen that surrounding the golden dome was a vast, semi-circular platform or courtyard of stone, with other stones set up perpendicularly around it.
“It is precisely like the arrangement of the Temple of the Sun in Peru,” said the professor.
“It will make a good place to land,” spoke the practical Joe.
“Doesn’t it seem almost like a sacrilege to bring a modern dirigible to earth in the very courtyard where the rites of ancient religion were practiced?” spoke Nat, who was an imaginative lad.
“Not at all,” said the professor, “and as for that ancient religion, if we had lived in the days when it flourished, I fancy we wouldn’t have liked it much. Like most ancient religions, it was a creed of bloodshed and violence. Human sacrifices may have been indulged in on those very stones we see beneath us.”
The boys agreed that this put quite another light on the matter, and the descent was made without further comment. The dirigible came to rest in the lost city of the Bolivian Andes at three o’clock in the afternoon. Mr. Tubbs was left to guard the Discoverer with old Matco, who refused to move one step through the silent, long-deserted streets. But the boys and the professor set out on a tour of exploration.