CLEMENS, SAMUEL LANGHORNE ("Mark Twain"). Autograph letter signed ("S.L. Clemens") to an unidentified relative "Dear Mr. Clemens," [London], 12 February 1900. 1½ pages, 8vo, embossed mourning stationery, on pages one and four of a four-page sheet. Regarding a photograph he has been asked to supply: "I am glad, & very much obliged to you. Whatever [my nephew] Sam Moffett approves I am sure I should approve. If you mean a photo which has not been printed, I am not sure that there is one -- except one the control of which has gone out of my hands in America. But the photographer will know. I will drop him a note. No, I have found it, & it has been printed in McClure's magazine..."