I have that LP recording, although not autographed. It has
nothing to do with the author Samuel Clemens, although the
song is from 19th-century riverboat culture. "Mark twain" is
elliptic slang for "marking on the twine" used to measure
the depth of the river.
Harry Belafonte sings beautifully, but if any Clemens
collector wants it for any reason other than the singer's
voice, I'd be fascinated to know why.
Vicki Richman
Bedford, Brooklyn NY