What does "gone round the world, but not into the world" mean in Patrick O'Brian's Desolation Island?

Question

What is the meaning of "gone round the world, but never into the world" mean in Patrick O'Brian's Desolation Island, and how does the character Jack understand that his friend means he was playing with sharps, and not that gambling is wasting his money?

The full context:

Earlier the character Jack went to a card room with Stephen. Stephen watched but did not play. Jack played high stakes cards with his usual group of people. Two of his group are cousins and they win much more often than anyone else.Stephen suspected his friend Jack was being colluded against, but was unable to find any evidence. Stephen also borrowed a large amount of money from Jack earlier that morning.

The following paragraph takes place immediately after leaving the card room:

Stephen knew that Jack had repaired his fortunes in the Mauritius campaign: even with the admiral's share, the proctors' fees and civilians` jobbery deducted, the recaptured Indiamen alone must have set him quite high in the list of captains who had done well out of prize-money. But even so... When they were clear of the house he said, "As such I should tell yet since I have so lately borrowed a large sum of money from you, I can scarcely cry up thrift, nor even common prudence, with much decency or conviction. I am struck dumb; and must content myself with observing that Lord Anson, whose wealth had the same source as yours, was said to have gone round the world, but never into the world."

"I take your meaning," said Jack. "You think they are sharps and I am a flat?"

Also I believe this is the Lord Anson being referenced.

Answer 1

Stephen, who shares a fondness for puns with Jack, plays on two senses of “world” here. Lord Anson went “round the world”, meaning that he circumnavigated the globe, but he did not go “into the world”, in the following sense:

world, n. 17. Fashionable society.

_{Oxford English Dictionary.}

Fashionable society is notoriously a place where sharp dealing takes place, and Jack, who has spent most of his life in the navy, can be naïve when ashore. In Post Captain, Jack was cheated by his prize-agent and cuckolded by Diana, and in Desolation Island, he is being defrauded by the projector Kimber, who pretends to be able to extract silver from the abandoned lead mines on his estate.

Stephen, however, faces some trouble in explaining the situation in a way that won’t make things worse. If he accuses Wray, Carroll, and Jenyns of cheating, then Jack, an instinctively honorable man, might feel duty-bound to defend them. He can’t tell Jack plainly that he’s a simpleton without causing offence. And he can’t hint at the need for Jack to be more prudent without exposing himself to a rebuke for his own imprudence. Hence his use of such an oblique hint.