I believe you're thinking of the day in 1893 when Twain took George
Griffin to the offices of _The Century Magazine_ and _St. Nicholas
Magazine_ in New York City. (Griffin had been his butler in
Hartford, but by this time Twain had given up the Hartford house, and
Griffin lived and worked in New York.) Twain wrote about this in an
unpublished piece called "A Family Sketch" which I quote from at some
length (with permission) in chapter 8 of _Was Huck Black? Mark Twain
and African-American Voices_.
>Sam wrote (somewhere) of taking his black servant with
>him on the rounds of NYC theatrical offices. I've
>thumbed the Collected Tales, Sketches, Speeches, and
>Essays; I thought I'd read it there. Can you help me?
Shelley Fisher Fishkin
The University of Texas