Sentence:  "No, Mr. Blenkinsop," he replied to the submissive curate, standing on his hearth-rug at full height and regarding the cornice as his habit was when he began to <WSD>monologize</WSD>—"no, I find it impossible to entertain such an accusation." 
Meaning of the word marked with <WSD> tags:  To deliver a monologue.