Sentence:  "Pity we live in the same century with that strange creature. Say, we have here two men who talked at length face to face with the fellow. Let's take a <WSD>Gallup poll</WSD>. Sumner, do you think Hitler is a madman?" 
Meaning of the word marked with <WSD> tags:  Any poll of the opinion of randomly chosen persons, used to represent the opinion of the public.