The novel makes heavy use of a Mancunian (Manchester) dialect in the speech of working-class characters. The Mancunian dialect was carefully researched by Gaskell, and its use was rather groundbreaking, in that it isn't simply used to indicate class distinction but is also generally meant to garner interest and sympathy for Milton characters.
Though the dialect is written in a distinctively choppy way, readers are clearly meant to be able to follow and understand what characters are saying. For example, early in Margaret and Bessy's friendship, Bessy tells Margaret, "If yo'd led the life I have [...] oh, wench! I tell thee thou'd been glad enough when th' doctor said he feared thou'd never see another winter." The written dialect is marked by cut-off vowels, occasional use of archaic pronouns like thee and thou, and older usages like "wench," which just means "young woman" without a pejorative connotation.
Dialect use is strongly class-coded. When Margaret picks up some Milton provincialisms, like "slack of work" (meaning proficient or hardworking), Mrs. Hale reprimands her for using "horrid Milton words," specifically "factory slang," and worries about what Margaret's snobby London aunt will think. For Margaret's part, she thinks such language is appropriate for her to use while living in Milton, and using it signals that she considers herself to be on the side of the working poor.
