"Good, loyal old Hippy," replied David. "The surprise is ready, but even
if it had not been, there is no exercise so beneficial to stout people as
walking."

"Well, bring it on, bring it on," exclaimed Reddy. "We are waiting
patiently."

"Curb your impatience, Sorrel Top," said David. "Just follow me, and see
what I have to show you."

They helped little Mrs. Gray, who was nimble in spite of her years,
through a broken gap in the wall of the Omnibus House. The old ruin was
more picturesque than, ever in its cloak of five-leafed ivy which the
autumn had touched with red and gold. A lean-to had been built against the
back wall of the building, fitted with a stout door on the inside and a
pair of doors on the outside.

"I rented this plot of land from the farmer who owns the orchard,"
explained David, taking a key from his pocket and opening the door in the
stone wall. "This was about the best place I could think of for
experiments, partly because it's such a lonesome place, and partly because
there is a clear open space of several hundred yards back here without a
tree or bush on it."

It was dark inside until he had opened the double doors in the opposite
wall, when the slanting light showed them an aëroplane; not a little
gymnasium model this time, but a full-fledged flying machine, a trim and
graceful object, even at close view.