been to a wonderful underground city of gold in Mexico, and it was soon after their return from this perilous trip that Tom had begun the work of changing his old aeroplane into a speedier craft.
This had occupied him most of the Winter, and now that Spring had come he had a chance to try what a re-built motor, changed propellers, and different wing tips would do for the machine.
The time had come for the test and, as we have seen, Tom had some difficulty in persuading anyone to go along with him? But Ned finally got over his feeling of nervousness.
"Understand, Tom," spoke Ned, "it isn't because I don't think you know how to work an aeroplane that I hesitated. I've been up in the air with you enough times to know that you're there with the goods, but I don't believe even you know what this machine is going to do."
"I can pretty nearly tell. I'm sure my theory is right."
"I don't doubt that. But will it work out in practice?"
"She may not make all the speed I hope she will, and I may not be able to push her high into the air quicker than I used to before I made the changes," admitted Tom, "but I'm sure of one thing. She'll fly, and she won't come down until
