"What do you mean?" asked Barton, stepping quickly toward him as if to strike him.
The man's hand was upraised, but the determined way in which Rob met his angry glare caused him to drop it.
ROB WAS JUST IN TIME TO CATCH SIGHT OF A MOTOR BOAT, SLIPPING BEHIND THE SPOT OF LAND.
"I want you to quit followin' me around, that's all," he said.
"I guess this island's big enough to hold all of us," snapped Merritt, "and as for following you around, we have other and better occupations on our hands."
The machinist made an angry reply and set off across the island at a rapid pace. As he did so an odd incident took place on the island behind which the motor boat had vanished.
On a staff which the boys had not previously noticed a red flag began to glide up and down. Sometimes it was hoisted quickly and then again slowly.
"What in the world are they doing over there?" wondered Merritt.