Sentence:  He constitutes, probably, the identical exception which Sir Boyle Roche had in his mind's eye, when he broached his famous problem, that "a man cannot be in two places at once, "barring" he is a bird." The <WSD>"skip</WSD>", or according to the Oxford etymology, the man-vulture, is not fit for his calling who cannot time his business so as to be present simultaneously at several places. He must be at Kinshan's on Carlisle Bridge, for Mr. Moriarty's half-pound of tea, at the very moment that "Sir" Looby, in the Botany Bay Square, requires his three eggs; and the Billy Sheridan of the day is singing out, like Stentor, from the tiles and skylights of a coctile edifice beside the library, for the "lazy rascal!" 
Meaning of the word marked with <WSD> tags:  A college servant.