They could see it for themselves.
"What did I tell you ?" asked Captain Spark triumphantly of Mrs.
Henderson.

"I said the voyage would make a man of Bob, and it did." "The voyage or the shipwreck ?" asked Mrs.Henderson.
"I guess it needed both," ventured Bob's father.
Of course Bob was the hero, of all his associates, and they never tired of hearing his stories of what had happened.

Later it was learned that Second-Mate Bender and his men had been picked up by a passing vessel and saved.

As for Captain Obediah Hickson, when he heard that Bob had returned, he hastened to see him, took him off into a corner and whispered: "Did ye git th' treasure, Bob ?" "No, captain.

I don't believe there was any.