n we found they were tied at the dock
we didn't think you were out on the water. Then when it stopped raining
Bert and I started out to find you and so did Sam, though he went a
different way."

"And we called and called to you," said Bert. "Didn't you hear us
shouting?"

"Maybe that was the noise we heard in the cave," said Freddie to his
sister.

"What about this cave?" asked Bert. "Tell us where it is."

Then, riding back to camp in the goat wagon, the two small twins told
again of the big hole in which they had taken refuge from the storm.

"I'd like to see that," Bert said. "We'll go there to-morrow."

"We can walk there, or Whisker can take us," said Freddie. "And then we
can come home in the boat, but you'll have to take some oars, Bert."

"That's so--there _is_ a boat!" exclaimed the older Bobbsey boy. "I
wonder whose it can be?"

But they did not learn at once, for the next day, when they all went to
the cave--including Mr. and Mrs. Bobbsey--the boat was not there.

"Somebody untied it and took it away," said Freddie, as he pointed out
the rock to which he had made fast the rope.

"Are you sure you tied it tightly?" asked his father.

"Yep. I made the same kind of knot you showed me," and Freddie told how
he had done it. Flossie, too, was sure her brother had fastened the boat
properly.

"Well, then somebody's been here in the cave," said Bert. "Say, it's a
big place, Daddy! Can't we get a lantern and see where it goes to back
there," and he motioned to the dark part.

"Some time, maybe, but not now," said Mr. Bobbsey, who, with his wife,
had walked along the island path to the cave while the children rode in
the goat wagon. "I didn't know there was a cave on Blueberry Island. I
don't believe many persons know it is here. But the boat might belong to
some of the berry pickers, and they hunted for it until they found it."

"Did the blueberry pickers make the funny noise in the cave?" asked
Flossie.

"I don't know," replied her father. "I don't hear any noise now. I
presume it was only the wind."

Mr. Bobbsey and Bert, lighting matches, went a short way back into the
cave, but they could see very little, and the children's father said
they would look again some other day.

"But, Flossie and Freddie, you mustn't come here alone again," said Mr.
Bobbsey.

"If it rains and we're near here can't we come in if we haven't an
umbrella?" asked Freddie.

"Well, yes, perhaps if it rains. But you mu