"I didn't," said Sammy.
"There it goes!" cried Frank. "Listen!"
As they listened intently they all heard a dull boom, coming from somewhere in the distance.
"A cannon!" cried Bob.
"Someone is firing at us!" exclaimed Sammy.
"More likely it's a signal gun!" burst out Frank. "Some ship has seen our distress signal. Come on up deck!"
He rushed from the table, followed by the others. Then, to their surprise and delight, they saw a steamer headed directly for them, and from her bow there shot a puff of white smoke. It was a signal gun she was firing, to let the boys know she was coming to their rescue.