Twain does mention this in Roughing It, Chapter 25 page 199, with illustration. On Fri, 2014-02-14 at 22:05 -0500, Robert E Stewart wrote: > Help. Someplace I read, recently, that Orion Clemens sent an unsigned > invoice to Washington for firewood delivered by an Indian. Washington denied > payment. > > Sam then helped the Indian make a "very shaky" X as "his[X]mark and the > bill went through with no problem. > > Can anyone help me with a cite? > > Bob Stewart