UCCESSFUL MODEL

Mr. Giddings was glad to accept the invitation to the trial flight. He
and his son met the Ross boys at the old race-course Saturday
afternoon. This immense, level field, with its one-mile oval and great
empty sheds, at one time had been the county's boasted fair-grounds,
but two years prior to the opening of our story it had been sold to Mr.
Giddings, whose residence property stretched down the side of Shadynook
Hill and joined it. New fair-grounds had then been established in
another and more centrally located section of the district. In the old
grounds the boys of the neighborhood now went to fly their kites and
model airplanes, to hold impromptu bicycle and foot races, and to play
tag and hide-and-go-seek in the cavernous sheds and around the numerous
sagging stables.

It was late in the afternoon--just before dusk, when the winds would be
at their quietest, and others not likely to be present--that our
friends arrived at the field. There was not a soul to be seen. Paul,
who had carried his precious Sky-Bird, freed it from the wrapper and
held it up for Mr. Giddings to see. The night before he and John had
put the finishing touches to the delicate structure by adding another
coat of varnish and attaching the little rubber-tired aluminum wheels
to the axle.

As Paul now held it up before the gaze of the great newspaper man, Mr.
Giddings made no effort to restrain his admiration. "What a little
beauty!" he cried. "Why, it's almost a perfect mechanical
representation of a bird!"

"Isn't she a dandy, dad?" put in Bob, his eyes snapping.

"The Sky-Bird is really more of a bird than you may think, Mr.
Giddings," declared Paul.

"Yes," added his brother John. "As you probably know, sir, a bird gets
its great buoyancy from the fact that every bone in its body is hollow;
in flight it fills these bones with a very light gas, which is formed
by an action of its lungs in drawing in air. We have adapted this
principle in the wings and fuselage of this little machine. They are
airtight and filled with compressed helium-gas, which is
non-inflammable and nearly as light as its highly volatile rival,
hydrogen-gas."

"Hydrogen-gas is surely a dangerous commodity around fire," said Mr.
Giddings. "I understand that when the big English dirigible R-34 came
across the Atlantic last summer she was filled with hydrogen, and that
her commander and crew all wore felt-soled shoes, so that they would
not