In response to Matthew Miller's question about a Pictorial Biography--

Milton Meltzer's _Mark Twain Himself, A Pictorial Biography_ does
contain a photograph of Grant and his family (p. 195) but Twain is not
in that photo. The other picture of Twain and Grant together in
Meltzer's volume is an artist's rendering (p. 106) -- not an
actual photo.

--Barb