"I'm afraid I'll have to," answered his son with a smile.

"Go? Of course he'll go!" burst out Mr. Damon. "And I'm going with
him; can't I, Tom?"

"Surely. The reason Mr. Illingway sent me the letter was to tell me
about the city of gold. He thought, after my travels in Africa, that
to find a buried city in Mexico would be no trouble at all, I
suppose. Anyhow he suggests that I make the attempt, and--"

"Oh, but, Tom, just when I am perfecting my gyroscope!" exclaimed
Mr. Swift. "I need your help."

"I'll help you when I come back, dad. I want to get some of this
gold."

"But we are rich enough, Tom."

"It isn't so much the money, dad. Listen. There is another part to
the letter. Mr. Illingway says that in that underground city,
according to the rumor among the African natives, there is not only
gold in plenty, and a number of small gold statues, but one immense
big one--of solid gold, as large as three men, and there is some
queer mystery about it, so that white traveler said. A mystery he
wanted to solve but could not."

"So, dad, I'm going to search for that underground city, not only
for the mere gold, but to see if I can solve the mystery of the big
gold statue. And if I could bring it away," cried Tom in great