o be awake and to attack us this way?"

"I think he must have had a mate, perhaps a family, nearby," replied
John. "I have read that the mother and her babies always go up into a
tree to sleep, while the father squats down at its base to guard them,
and here he sleeps with one eye open and the other closed, as the
saying is. At least he arouses at the slightest sound of an enemy. We
probably awakened him by our shouts while in bathing, and being so
close to him when we came back along a slightly different path, he
thought we were going to attack the family upstairs, and showed fight
right away."

The little party regained their airplane without further incident; the
radiator was drained, and the fresh water put in. Then, feeling that
there was no further danger of the engines running hot, they took off.

As the Sky-Bird arose into the air, the flyers noticed that Grandpa the
monkey was slightly excited. This they attributed to the presence of
the gorilla's skin; but when they saw Grandpa continue to dash wildly
about the cabin, from their shoulders to the rear window, out of which
he would take a quick look only to fly back to them and chatter wildly
and coweringly, Paul thought he would see what could be the trouble.

One glance was enough. He shut the open window with a bang, and turned
to his companions with a pale face.

"Fellows," said he; "we've got a passenger!"

"A passenger?" cried they.

"Yes," said Paul, "a monstrous big snake!"

CHAPTER XXI

THE DOUBLE LOOP

For a moment or two John and Bob stared at Paul blankly, unable to
comprehend the import of his announcement. Tom was at the throttle,
and while he had heard the startling words, he was too occupied in
guiding the Sky-Bird to do anything except take a quick glance backward.

"A snake?" repeated Bob.

"Not on the machine?" cried John.

"Yes," Paul said, with a seriousness which left no further doubt as to
the truth of his statement. "He's a whopper--must be twelve or
fourteen feet long and as thick as my leg. He's there on the fuselage
just outside of the window, hanging on for dear life. If I hadn't shut
that window just as I did, I believe he would have crawled in here in a
minute."

John and Bob now hurried to the window and looked out. In the
moonlight they could distinctly see a huge reptile, either a python or
a boa-constrictor, coiled up in the angle formed by the juncture of the
airplane body and the broad base o