Dear Kurt Lawlor --
     In his autobiographical dictations Mark Twain did say he had the ms. of
*Tom Sawyer* typed, but according to Darryl Rehr -- a historian of the
typewriter who actually has a website devoted to the machine -- it was in
fact *Life on the Mississippi.*  There's an exhibit about this, with
pictures
of the early typewriters and a Remington ad quoting from the *North American
Review* publication of Twain's autobiographical writing, in my website "Mark
Twain in His Times."  The exhibit is in the "Connecticut Yankee" section,
under "Mark Twain, His Time and the Machine."  The site's address is
http://etext.lib.virginia.edu/railton.  I hope this helps.  Stephen Railton