Cub produced the chart and a hand-book diagram of a mariner’s compass about three inches in diameter.  Fortunately the chart was made of thin, vellum-like paper, almost transparent, so that when laid over the diagram, the minute points of the compass, indicated with clear black lines, could be seen through.  First the dot representing the town of Clayton was placed over the point at the center of the compass, with the north and south line of the compass exactly coinciding with the meridian of the town.  Then Cub traced on the chart lightly with a pencil the 47-1/2-degree northeast line of the compass.  Next he performed a similar operation with the center of the diagram over Rockport and next with the center of the diagram over Gananoque, following instructions in each of these cases with reference to the direction lines to be drawn.  The result was that the intersection of the three lines was at approximately the point indicated by the Rockport amateur.

“Now we’re ready to continue our search,” Cub announced.

“That’s pretty good progress, I must say,” Bud declared; “but here’s a new question to get us into trouble again.”

“Oh, for goodness sake, don’t,” pleaded Cub.  “You’ve had your example of what my mathematical dad can do with such foolish creatures.”

“Let him express his doubt,” suggested Mr. Perry with a smile; “for, if a man must doubt, he’d better shout than smother his ideas in a skeptic pout.”

“Yes, get it off your chest, Bud, and then take your medicine,” advised Hal.

“Well, suppose we find the island and nobody there, how are we going to know it’s the right one?”

This hit the other two boys pretty hard.  The possibility of such a situation had not occurred to either of them.  However, Cub preferred to take it in lighter vein, for he replied: 

“By his footprints on the sandy beach.  You mustn’t have a Crusoe Island without some footprints, you know.”

“The trouble is you’re anticipating too rapidly, Bud,” Mr. Perry advised.  “Columbus would never have discovered America in that frame of mind.”

“All right, I’ll change the frame,” said Bud.  “We’ll just go ahead and see what we shall see.”

“We’ve got to go ahead if Hal’s cousin is in peril,” declared Cub.

“Do you really believe the Crusoe boy is your cousin, Hal?” asked Bud.

“Of course that’s hard to believe, but the evidence points in that direction,” Hal replied.

“At least if he is your cousin, we know now that he wasn’t making monkeys out of us, as that last message, supposed to come from him, made it appear he was doing,” Cub admitted.

“Yes,” put in Mr. Perry; “it looks now as if he was telling a straight story all along.”

“If that’s true, then he’s probably in serious trouble right now,” said Hal.

“Probably a prisoner in the hands of robbers, if not worse,” Bud supplemented.