Definition of Dramatic Irony
Crane uses dramatic irony to demonstrate the randomness of fate and the occasional irrationality of optimism. At first, the men rejoice when they see a lighthouse in the distance, for they believe that it contains people capable of saving them. They even celebrate by sharing cigars. However, their rescue is not as expedient as they hoped it would be. The men do not see any signs of life at the lighthouse, nor does any ship come out to help them.
The four men make bitter comments about the lighthouse residents' eyesight, not realizing the real kicker—that the lighthouse is empty:
It is fair to say here that there was not a lifesaving station within twenty miles in either direction; but the men did not know this fact, and in consequence they made dark and opprobrious remarks concerning the eyesight of the nation’s lifesavers. Four scowling men sat in the dinghy and surpassed records in the invention of epithets.