Sentence:  "You know that Mr. Armadale is alive," pursued the doctor, "and you know that he is coming back to England. Why do you continue to wear your widow's dress?" &para; She answered him without an instant's hesitation, steadily going on with her work. &para; "Because I am of a sanguine disposition, like you. I mean to trust to the <WSD>chapter</WSD> of accidents to the very last. Mr. Armadale may die yet, on his way home." 
Meaning of the word marked with <WSD> tags:  A sequence (of events), especially when presumed related and likely to continue.