Mr. Damon when, after about an hour's work, they had jointly written a letter to the African missionary.
"We've asked him enough questions, anyhow," agreed the lad. "If he answers all of them we'll know more about the city of gold, and where it is, than we do now."
"Exactly," spoke the odd man. "Now to mail the letter, and wait for an answer. It will take several weeks, for they don't have good mail service to that part of Africa. I hope Mr. Illingway sends up a better map."
"So do I," assented Tom. "But even with the one we have I'd take a chance and look for the underground city."
"I'll mail the letter," went on Mr. Damon, who was as eager over the prospective adventure as was Tom. "I'm going back home to Waterfield I think. My wife says I stay here too much."
"Don't be in a hurry," urged Tom. "Can't you stay to supper? I'll take you home to-night in the sky racer. I want to talk more about the city of gold, and plan what we ought to take with us to Mexico."
"All right," agreed Mr. Damon. "I'll stay, but I suppose I shouldn't. But let's mail the letter."
It was after supper, when, the letter having
