"I tell you what we ought to do," Hal volunteered next. "Let's accept
this island as the center of probability."

"What in thunder is that?" Cub demanded.

"That's a good one on you, son," laughed the latter's father. "I thought
you were the highbrow of your bunch; but here's our subtle Tee-hee
putting a bit of clever phraseology over on you."

"Oh, I know what he means," Cub rejoined with a panicky haste to recover
lost prestige. "I was just giving him a dig. He's forever giving me one,
whenever I come along with anything of that kind."

"It indicates that his mind is maturing rapidly," said Mr. Perry.
"All right, Hal, we'll accept this island as a center of
probability--what next?"

"Why, let's cruise around about half a mile in all directions and pick
out those islands that look as if they might have concealed a prisoner
from view of passing boats."

"That's a good suggestion," said Mr. Perry. "Bob, start the boat again."

The inspection required about an hour, at the end of which they compared
notes and found that their island inventory disclosed the following
conditions:

Three possible places of concealment for the "Canadian Crusoe" had been
discovered. Two were small islands a short distance from each other in a