"Nothing here," announced Frank, after an inspection of the first one. And that was the result in all the others that they penetrated before dusk. By nightfall they had covered perhaps a quarter of the shore line and then they turned back.
A roaring blaze was kindled on the sand from the plentiful supply of driftwood that strewed the beach, and at the cheerful fire they sat and talked as they ate their supper.
"Jolly fun, isn't it?" asked Andy.
"It sure is, even if we don't discover anything. I wish Paul was along."
"Perhaps it's just as well he's home," commented the younger lad. "I have an idea that this man keeps informed of our movements, and don't fancy having him sneak up on us during the night, which he would be very likely to do if Paul was with us."
"That's so. But, speaking of night, what are we going to do about sleeping?"
"Under our boat, with our blankets spread out on the sands," said the younger lad. "It's plenty warm enough."
It was not a half bad way to spend the night, especially as the overturned rowboat kept off the chilly dew. Soon the two brothers were soundly sleeping. They did not bother to keep a watch and even allowed the fire to die out, taking the precaution, however, to put some wood under the boat, where it would be dry in case of rain in the night.
"Well, now for another try at the mysterious man!" called Frank, as he crawled out from under their shelter the next morning. "Maybe we'll have better luck to-day."
They set off directly after breakfast, and took with them their blankets and a supply of food. For they intended to make a half circuit of the island that day, and they figured that night would find them too far away from their camp to make it practical to return.