rson, beside himself with
rage, "I'll get even with you for this, see if I don't!"

Sam and Eph, who had picked themselves up, shouted other threats at
Dick. But he turned round and, with a pleasant smile, waved a hand as
the current carried his boat round the bend. He felt in high good
humor at the way he had gotten out of a difficult situation. It was
fortunate for him, though, that he had taken Masterson and his cronies
so utterly by surprise, otherwise the adventure might have had a
different conclusion.

He had established one fact, however, and that was that Masterson and
the others were spying on them every night and watching every step in
their preparations for the departure for Rattlesnake Island.

That night a strict watch was kept in the camp, all the adventurers
taking turns at sentry duty. But nobody came near the place.

CHAPTER XXVII.

THE PROFESSOR'S SECOND DILEMMA.

Early the next day old man McGee paid them a call. He came to take
back the burro they had hired from him for convenience in getting back
and forth from Yuma. He also wanted to get a ladder which had been
left at the deserted shanty. The old man rode into camp on a
razor-backed horse and professed great astonishment when he saw how
nearly completed the work on the Wondership was.

"But you kain't fool me," he said knowingly. "I may be old but I'm
wise. That thing fly? Why, you might as well tell me the Nat'nul Hotel
in Yuma could go kerflopping about in the air. By the way," he went
on, "frum ther talk in ther town you ain't ther only ones as is goin'
down ther river. There's three young chaps has bought two boats and
allows that they're fixin' to take a trip."

"Is that so?" exclaimed Jack with a significant look at his chums. "I
think we can guess who they are."

But old man McGee was busy fussing with the donkey and didn't hear
him. He was going to carry the ladder back to town on the little
creature's back. He lashed the ladder across the saddle so that it
stuck out on both sides of the burro, who viewed the proceedings with
a kind of mild surprise. It brayed loudly and flapped its long ears in
a way that made the boys laugh heartily.

"There," said old man McGee at last, "that's done. Now I reckon I'll
bid you so-long and good-luck, and be on my way. When are you goin'
ter start?"

"To-morrow morning," replied Jack, "if everything is all right."

"Hold on a minute," said Tom suddenly, as old man McGee was riding