"Then that must be the boys!" exclaimed Ed excitedly.
"But why don't they come on out?" asked Will, anxiously.
"Perhaps they have found Bert and don't want to leave him!" suggested Ed.
While the boys watched the red light, which seemed to glimmer from the very extremity of the cavern, it turned to blue!
"Now I've got it," cried Will almost dancing up and down in his excitement, "you know what that means, don't you?"
"I can't say that I do!" replied Ed.
"It seems to me that the Portland Boy Scouts are not very well posted," laughed Will. "One of the boys—which one, I don't know, of course—is talking to us in the Morse code!"
"Still I don't understand," said Ed.
"The red light means a dash," Will explained, "and the blue light means the dot. Now we'll see if we can catch what the boy is saying."
"But where does he get the red and blue lights?" asked Ed.