David Fiske, co-author of a new biography of the hero of 12 Years a Slave, saw the recent post here and has sent along a link to his own report on Samuel Bass, the Canadian carpenter played by Brad Pitt in the film.
Fiske's piece on Samuel Bass notes that the last known public appearance made by Northup was to have been an anti-slavery address in Streetsville (now Mississauga, Ont) in 1857 ... but it was prevented by rioting.
Solomon Northup: The Complete Story is published by Praeger and available here.
Fiske