nt that we will solve the whole problem very shortly."

"With mathematics?" asked Hal.

"You see we are moving in a geometric circle, do you not?" Mr. Perry
returned with a smile.

"Oh, look there!" suddenly exclaimed Max. "A motor boat."

But there was no need of calling attention to so conspicuous an
appearance. All saw it at the same time. It darted out from a narrow
passage between two of the smaller islands surrounding the one that Alvin
Baker had denominated "Friday." It was a small cabin runabout, very
neatly designed and constructed; and apparently with a draft measured
only by inches. She made directly for the yacht.

"Catwhisker, ahoy!" called out a youthful voice, and a wide-awake
red-haired boy put his head out of one of the port windows of the cabin.
"I want to come aboard with important information."

Of course, everybody aboard the Catwhisker was astonished, but Mr. Perry
signaled Cub to reverse the engine. This was done, and the yacht soon
lost all headway. Then the runabout glided close up to the larger power
boat, and the boy who had hailed her sprang over the two adjacent rails.
Another boy could be seen in the pilot seat of the smaller craft.

"My name is Halstone," announced the visitor. "I am from--"

His announcement was drowned with exclamations of surprise from
his audience.

"Hal Stone!" repeated several in chorus, including the Catwhisker's Hal
Stone himself.

"Yes, Halstone," reiterated the challenged youth; Frederick Halstone.
"Anything funny about that? I'm the reporter from Watertown who was
dot-and-dashing with you folks last night. I got in touch with a friend
of mine right away who owns that motor boat, and he was crazy to make the
trip here after this big scoop. I'm here representing not only my paper,
but the Associated Press. We located Friday Island here without any
difficulty. But I brought my radio outfit and loop antenna along and
listened in just a short time ago to some messages between somebody who
said he was a prisoner on the Catwhisker and another fellow on a boat in
the cove I just came out of. You'd hardly think a boat of its size could
get in there. It's about the same size as the Catwhisker, and is built
and painted like it. I think you'll find the solution of your big mystery
is right there. They're loading a lot of stuff in boxes from a cave in
the steep bank of that small island next to the big one. The cove is
between these two small islands, which, you s