In To Kill a Mockingbird what causes the shiny clean line on the dull wire of the remains of Scout's costume in chapter 29?
Chapter 29 begins with the announcement that Bob Ewell is dead, and Heck Tate is trying to piece together what happened, so Scout begins to tell what she remembers as Jem is still recovering.
Scout brings up her costume, and Tate asks to see it. Looking it over he claims, "This thing probably saved her life" (Lee 308), mentioning how the beat up costume softened the blows of Bob Ewell. Tate then points out the "shiny clean line on the dull wire (308) which probably refers to a slash mark in the costume made by Bob Ewell's knife.