knees, and then drew himself erect, to make a
discovery that thrilled him through and through.

CHAPTER III.

JACK TAKES A HYDRO-AEROPLANE MESSAGE.

"Oh! murder! what a big birrd!" Jimmy was crying out.

A shadow had fallen upon the water close by, and the distant cries of
the other young motor boat boys could be faintly heard. Jack, looking
hastily up, saw a strange thing that had extended wings like a monster
bird, apparently swooping down toward the surface of the wide river.

Of course he knew that it was an up-to-date flying machine, and the
presence of aluminum pontoons under the body of the contrivance also
told him that for the first time in his life he was looking at a
hydro-aeroplane, capable of alighting on the water and starting up
again, after the manner of a wild duck.

Even as the two in the _Tramp_ stared, the queer contrivance skipped
along the surface of the Delaware, sending the water in spray on either
side. Then it seemed to settle contentedly there, not ten feet away
from the motor boat.

There was a young fellow squatted in the seat where the various levers
could be controlled. He was dressed after some odd fancy of his own,
calculated to serve in the cool air of the upper strata. To Jimmy the
vision was very startling.

"Why, say, it's a real birdman after all, Jack!" he cried, as though he
had only discovered this remarkable fact after the machine had come to
a stop close by.

The aviator laughed aloud.

"What did you think it was, young fellow, an old-time roc come back to
life?" he called out; waving a hand at them cheerfully.

Jack had shut off the engine at the time he heard the first exclamation
from his teammate, and at this time they were hardly more than moving
with the ebb tide, so that in reality the boat drew closer to the
hydro-aeroplane with each passing second.

"You gave us a little start, that's all," laughed Jack. "Of course, I
knew what it was as soon as I saw the pontoons underneath. They seem
to do the trick first rate, too. Seems to me I'd like to sail in one
of those things, if I ever had the chance."

"It's a great experience, all right," replied the aviator; "but the way
things are going right now, only a very few fellows are fitted for the
work. But are you in company with those other two jolly little boats
way off yonder?"

"That's right," sang out Jimmy, determined to have his little say with
the bold navigator of the upper currents; "we