Sentence:  And then it appeared to be forgotten, or, at least, men seldom spoke of it, and presently it came to be accepted as the popular belief that the robbery had been committed by a gang of desperate tramps, this theory being confirmed by a certain exploit subsequently in the San Juan country, an exploit wherein three desperate tramps assaulted the <WSD>triweekly</WSD> road-hack, and, making off with their booty, were ultimately taken and strung up to a convenient tree. 
Meaning of the word marked with <WSD> tags:  Published three times a week.