"Oh, we'd have to have something good to eat," put in Dave. "That's three-quarters of the fun."
Much to their surprise, in walking to the center of the island, they ran into Doctor Clay and Mr. Dale. Both had some bits of rocks in their hands and the doctor had a geologist's hammer as well.
"Well, boys, what brought you?" asked the head of the school, pleasantly.
"Oh, we just stopped for fun," answered Dave. "We didn't know you rowed so far."
"We are knocking off a few geological specimens for the school cabinet," answered Doctor Clay. "These are not particularly valuable—but every little helps."
The boys remained with the men for a quarter of an hour, and then walked back to the shore. As they did this, Dave suddenly put up his hand.
"What is it?" asked Phil and Plum, in a breath.
"Thought I heard a motor boat."
"Perhaps Nat Poole's boat is near the island," suggested Gus.
"Oh, there are a dozen motor boats on the river now," answered Phil. "There, I heard it, but it's a good distance off."