ing all three boys, filled with new confidence and energy,
met at the fairgrounds as soon as they had had their breakfasts. Paul
carried two rolls of fresh blue-prints, which he and John had made
while their mother was preparing the meal. One of these sets he gave
to Bob to take home as his own special property, and the other one he
spread out on the workbench for consultation as their needs required.

Up to this time no effort had been made to keep children and curious
adults out of the grounds, but as their machine was now beginning to
take on real form, they determined to do this. On a piece of board,
Paul printed in large letters, "Private Grounds; Keep Out," and Bob
nailed this up on the outside of the high board fence at the entrance.
The gate itself they closed and barred on the inside.

"Guess that will be a sufficient hint to the grown-ups," said Bob with
a grin. "If the kids climb over, we'll fasten a red flag to the front
of our big hangar and paint 'Dynamite' in letters a yard long across
the front of the building."

"Yes, and if that doesn't keep them away we'll turn the hose on them,"
laughed John.

Then they fell to work on the new airplane, applying themselves like
beavers. All three boys had had the splendid benefits of manual
training when they were in the public schools, and knew how to handle
every machine they had set up. In addition to this, Paul and Bob were
first-class amateur machinists, as their courses of engineering in
Clark Polytechnic embraced the use of metal-working appliances of the
latest design, as well as wood-working machinery, and they could have
operated other machines had they needed them.

That evening the workers went back home tired but well satisfied with
their progress. The next day the shavings flew again, and by the
latter part of the week they had begun to assemble portions of the
fuselage, using a waterproof glue which had been especially prepared
for airplanes, and applying galvanized screws to withstand rust in damp
atmospheres.

As the days went by, the boys, like almost everybody in the country,
watched the newspapers eagerly for reports of the progress of the
contestants in the big Air Derby around the world. Only four of the
eleven aircraft to start had succeeded in getting across the
treacherous Atlantic, two of these being dirigible balloons, one a
flying-boat, and the other a Vickers-Vimy biplane. After landing on
European soil one of the lucky ai