“Excuse me for saying so,” stuttered Joe; “but it sounds like—like a wonderful fairy tale.”

“It is one,” said the professor smilingly, “a fairy tale which, with the aid of you boys, I hope to make true.”

“With our assistance?” echoed Nat in an astonished tone.

“Yes. I really believe that it was Providence that threw me in the path of you boys. You are exactly the type of self-reliant, clever young Americans that I need for assistants in the work. Are you willing to charter the Nomad to me, land me on the South American coast, instead of in California, and give me your services, for a substantial compensation?”

“I—I beg your pardon,” Nat managed to choke out, “but the idea is so entirely new to us that I think we shall have to hold a consultation first.”

“Take your time,” said the professor airily; “take your time. It is characteristic of me to arrive at quick decisions, as Mr. Tubbs knows, and I don’t mind telling you that I shall be very disappointed if you don’t see your way to accommodate me. We are now almost on a straight course for the coast of South America. If, on the other hand, we landed in Santa Barbara, I should have to take steamer from San Francisco to South America, and I might arrive too late.”

“Why?” demanded Nat. “Is there any one else in search of the lost city?”

“My colleagues fear so,” was the rejoinder. “The documents passed through many hands before they reached scientific ones, and the treasures of the lost city, if they come up to all accounts, are enough to tempt any one to search for them for their intrinsic value alone.”

“Have you any idea who the men are who may prove your rivals?” asked Nat.

“I have—yes. But I do not wish to discuss that phase of the matter any more just now. Suppose you and your friends hold your consultation and then notify me of its result?”