Where in the Mark Twain canon did I read this?  (Flaky and undoubtedly
misremembered details are in parentheses.)

Clemens and some friends have attended a public event (Independence Day
rally?) somewhere west of Boston.  They return (to Cambridge?) late and
tired.  His host's wife (Mrs. Howells?), having never met Sam before, is
somewhat alarmed at his disheveled appearance (and sealskin coat?).

My reason for wanting to recapture this incident is that I have plans to
give a Mark Twain talk this fall at the Newton (Mass.) Historical Society,
located right by the railroad tracks that have headed west from Boston since
1850 or so.  If I could make a plausible suggestion that Sam and riotous
friends once passed right by the lecture site, it might add a spark to the
talk.

Attempts to search the Web and my long Twain bookshelf have failed so far.
Can any of the assembled sharp memories come to my aid?

Thanks,

Henry Feldman