When Dick rents a room on Mott Street from Mrs. Mooney, he amazes his landlady by telling her, in a moment of dramatic irony, that he's coming from Astor House:
“I’ll bring over my baggage from the Astor House this evening,” said Dick in a tone of importance.
“From the Astor House!” repeated Mrs. Mooney, in fresh amazement.
“Yes, I’ve been stoppin’ there a short time with some friends,” said Dick.
This statement rightly astounds Mrs. Mooney, since the Astor House was one of America's most famous luxury hotels at the time of Alger's writing. Technically, Dick is telling the truth (as befits his honest personality) because Frank and Mr. Whitney are staying at the hotel, and he did leave some belongings with him. But because of the way Dick phrases this statement, Mrs. Mooney believes that he's a wealthy young man. This is an instance of dramatic irony because her incorrect understanding of the situation is so different from what the reader knows to be true of Dick's circumstances.
Much like the verbal irony Dick employs in his self-deprecating jokes, dramatic irony injects a note of humor into the narrative here and helps to sustain the novel's general mood. This episode also reminds the reader of Dick's mischievous personality: though he's too honorable to actually lie to anyone, Dick is clever enough to make fun of himself and others in more subtle ways. More broadly, this moment of dramatic irony sets the stage for Dick's journey of upward mobility. While the thought that he might stay at the Astor House is ironic enough to seem absurd at this point in the novel, such a prospect is not so hard to imagine by the end.
