ified. I don't mean to say that it would be impossible to mystify me
under any circumstances. For instance, if the man in the moon should
suddenly jump down on the earth and give me a brick of green cheese, and
then jump back again before I could say 'thank you' I presume I'd be
greatly mystified."

"Your illustration won't stand a test of reason, dad," Cub objected. "To
test whether it is possible for you to be mystified you must offer a test
that is possible."

"That's precisely why I offered that impossible illustration," Mr. Perry
smiled. "I wanted to see if any of you boys would catch the
inconsistency. You just call this affair a mystery as long as you think
it is one, but after it is cleared up, I fancy you'll have difficulty in
looking back and picturing it as a mystery in your minds. But I didn't
intend to take us off our subject. I was going to answer Bud's argument
that something of importance might develop while we were gone. Yes, that
is true, but it wouldn't be necessary for all of us to go. Two of us
might make the trip and the other two remain here."

"That's a good idea," declared Hal. "Suppose you and Cub go and leave Bud
and me here to look after the camp and watch for developments?"

Mr. Perry did not reply at once. Something new seemed to have slipped
into his mind and appeared to be giving him some concern.

"On second thought," he said after a few moments of silence; "I'm
inclined to withdraw my suggestion."

"What's up now, dad?" Cub inquired.

"I was just recalling a portion of Hal's cousin's diary," his father
replied. "According to that, it seems that rough characters visit this
place sometimes."

"Oh, we're not afraid," Hal protested. "Besides, you could make the trip
there and back in a few hours."

"Well, we'll think it over and decide in the morning what we'll do," said
Mr. Perry.

"Meanwhile, I tell you what we ought to do," Bud proposed. "It's an hour
before dark and we'd have time to bring Hal's wireless outfit up here and
hook it up before the sun sets."

"That's a peach of an idea," declared Cub, jumping to his feet in his
eagerness. "I've got two hundred and fifty feet of extra wire and some
insulators on the boat and we can put up an aerial here without taking
down the one on the Catwhisker. Then we can shift the radio outfit back
and forth to the island and to the boat as we please."

"Good!" exclaimed Hal. "I'm with you on that. Let's get busy and not
waste a minute