That sketch was made for a postera* advertising Mark Twain's lecture at the Brooklyn Academy of Music, February 7th, 1873.** * Mark Twain Himself by Milton Meltzer, p.118 **Mark Twain Speaking by Paul Fatout, p. 650 The illustration itself is in the New York Public Library. Hope this helps. Richard Henzel www.richardhenzel.com/marktwain.html