Part II of the novel features many literary devices, some more obvious than others. One of the most easily identifiable literary devices is situational irony.
One example of situational irony would be that Boo Radley rescues Jem and Scout. Boo is perhaps the last character in the novel whom the reader would expect to become involved in a violent confrontation, yet it is he who fights for the children’s lives, killing Bob Ewell in the process.
Another example of situational irony concerns Scout’s ham costume. When Bob Ewell attacks Scout and Jem, it is Scout’s costume that prevents her from running away. Ironically, it is also Scout’s costume that protects her from injury or death. In Chapter 29 when Atticus observes that Scout’s costume “was crushed to a pulp,” Heck Tate says, “This thing probably saved her life.”
There are other examples of literary devices that perhaps are more subtle. At the conclusion of Chapter 22, Bob Ewell encounters Atticus by the post office and spits in his face. In the first sentence in Chapter 23, Atticus says, “I wish Bob Ewell wouldn’t chew tobacco.” This is an example of understatement, considering the terrible insult Atticus has just endured.
Also, after spitting on Atticus, Ewell vows he would “get [Atticus] if it took the rest of [Ewell’s] life.” This is an example of foreshadowing; Bob Ewell’s threat hints at his subsequent attack on Atticus’s children.
In both chapter 21 and 24 we see Tom as a mockingbird symbol, and in chapter 30 we see the mockingbird symbol again, but this time we see it as Boo Radley. In chapter 21 the verdict is announced, and in 24 Atticus explains that Tom was shot. "Seventeen holes in him. They didn't have to shoot him that much." All Tom did was help Mayella (for free) and his pay for that was his life.
In chapter 30 Scout sees what Heck and Atticus decide is best for Boo and his life. "Well, it'd be sort of like shootin' a mockingbird, would it?" She knew that his good deeds would make him a hero, and with his shy ways, that would about kill him. So he, too, is a mockingbird symbol.
Another literary device that's used is irony. Mrs. Merriweather comments about J Grimes Everett and his selfless acts with the Mrunas. That makes her appear understanding of those who are in the minority and the help that they need. The irony is that she sat there in the home of Atticus Finch and disapproved of his helping Tom Robinson. "Now far be it from me to say who, but some of 'em in this town thought they were doing the right think a while back, but all they did was stir 'em up." It proves her to be a hypocrite, but irony is the literary device being used to show her true character.