I first learned of the following story in a long-forgotten book of maritime lore entitled Unsolved Mysteries of Sea and Shore.  Authored by Edward Snow, it was published in only one edition in 1963.  As it is a difficult volume to procure, it will be useful for me to retell the tale here in abbreviated form, so that readers can form their own conclusions on the purposes of an elusive and sinister figure named William Kellogg Thompson.