touches to the gun carriage, ready for the test that was to take place about noon.
"It doesn't look as though it would burst," observed Ned, as the aircraft hovered over the big artificial lake.
"No," agreed Tom. "But I suppose the engineers want to be on the safe side in case of damage suits. I want to take a look at the place where the other valley comes up to this at right angles."
He steered his powerful little craft in that direction, and circled low over the spot.
"A bursting projectile, about where that big white stone is, would do the trick," murmured Tom.
"What trick?" asked Ned, curiously.
"Oh, I guess I was talking to myself," admitted Tom, with a laugh. "I may not have to do it, Ned"
"Well, you're talking in riddles to-day, all right, Tom. When you get ready to put me wise, please do."
"I will. Now we'll get back, and fire our first long shot. I do hope I make a record."
There was much to be done, in spite of the fact that the foreman of the steel workers assured Tom that all was in readiness. It was some time that afternoon when word was given for those
