A friend who collects pens gave me a copy of an ad for the Conklin Crescent self-filling fountain pen that has a 1903 endorsement by S.L. Clemens. (The add features the pen, an image of the white-maned Clemens, and a facsimile signature.) She tells me that Clemens may have endorsed other pens and she is looking for other ads. The copy reads: New York, Oct. 1, 1903 Dear Sirs: I prefer it to ten other fountain pens, because it carries its filler in its own stomach, and I cannot mislay it even by art or intention. Also, I prefer it because it is a profanity saver; it cannot roll off the desk. Very truly yours, S. L. Clemens (The pen had a filling mechanism that projected from the barrel and would keep the pen from rolling.) Did Twain/Clemens typically write such ad copy himself? Was it more likely that an advertising agent concocted a likely quotation and applied it over the Clemens signature? Has anyone done any work in this area of Twain's endorsements? Dennis Kelly San Francisco