Sentence:  Mr. H ..., whom no distinctions of that sort seemed to disturb, scarce gave himself or me breathing time from the last encounter, but, as if he had task'd himself to <WSD>prove</WSD> that the appearances of his vigour were not signs hung out in vain, in a few minutes he was in a condition for renewing the onset 
Meaning of the word marked with <WSD> tags:  To demonstrate that something is true or viable; to give proof for.