Pretty sure 'barn' in this sense means 'bound', as in 'heading' or 'going'. "Hey up, Young Pokey. Is tha barn darn t' pit?" reads to me as "Hello, son of Poke. Are you heading down the pit?"
Given that this conversation appears to be directed at the child in question, and the child responds by saying "Ah'm barn darn t' thutty-niners", seems unlikely he'd refer to himself as a 'barn'. Makes more sense to me that he's agreeing - he's bound down the thirty-niners.
Given that this conversation appears to be directed at the child in question, and the child responds by saying "Ah'm barn darn t' thutty-niners", seems unlikely he'd refer to himself as a 'barn'. Makes more sense to me that he's agreeing - he's bound down the thirty-niners.