"It's one that has three sets of planes, one above the other. A biplane has two sets of planes, and a monoplane only one. Triplanes are larger, and, as far as I've been able to learn, not as satisfactory as either the biplanes or monoplanes. But that's not saying Andy's won't be a success. They certainly are busy in there, though! Andy is flying around like a hen scratching for her little chickens!"
"See anything of his cronies?"
"Yes, Pete and Sam are hammering away. There are a couple of men, too."
"Yes, the machinists. Oh, I guess Andy expects great things from his airship."
"Have you heard what he's going to do with it, Ned? Make flights for pleasure, or exhibit it?"
"No, I haven't heard. Look out, Tom, the ladder is slipping!"
As Ned spoke this warning, the window of the airship shed, through which they were looking, was suddenly raised. The ugly face of Andy Foger peered out. He caught sight of Tom and Ned.
"Get away from there, you spies!" he yelled. "Get away from there, Tom Swift! You're trying to steal some of my ideas! Get away or I'll make you. Sam, bring me my gun! Pete, go
