Sentence:  Carried somehow, somewhither, for some reason, on these surging floods, were these travelers, of <WSD>errand</WSD> not wholly obvious to their fellows, yet of such sort as to call into query alike the nature of their <WSD>errand</WSD> and their own relations. It is easily earned repetition to state that Josephine St. Auban's was a presence not to be concealed. 
Meaning of the word marked with <WSD> tags:  The purpose of such a journey.