Yep, Larry is right about SLC being willing to join the railway trade in books.
 There were times in his life, though, when such trade conflicted with his
other interests: it would have been even more difficult for Twain to gain
acceptance among the Boston brahmins of literature in the 1870s if he allowed
his work to be published in that fashion, and the competition between railway
editions and subscription sales hurt the subscription publishing with which SLC
 identified himself and in which he invested. After the bankrupt 1890s, he saw
his works as a future fortune, which cheap paperbacks might undermine.  He
never relished selling his books in cheap editions (with some exceptions, like
the _(Burlesque)Autobiography_ amd the Sketch book he later sold to Aetna as a
promotional freebie), but the money always perked up his appetite for any new
market. Thanks for calling me on it, Larry.
                                               Andy Hoffman