From The Museum of Musical Instruments I learned that Mark Twain played the guitar:
[Twain] was a passionate guitarist and singer during the 19th century’s Romantic era. His songs were woven with graphic stream-of-consciousness imagery, and his musical styles included gospel, slavery blues, love songs, political satire, folk, and burlesque.
He apparently played a Martin, style 2 1/2-17.
(NOTE: Image isn’t Mark Twain. Hell, that might not even be a guitar he’s holding – could be a ukulele.)
