Who -- or what -- was Spring-heel Jack? Some suspected that he was a rowdy nobleman, Henry, Marquis of Waterford, who died in 1859. Doubters countered that Jack-like leaps are physically impossible. During World War II German paratroopers who put springs in their boot heels got broken ankles for their efforts. Was Jack an alien? In July 1953, three Houston residents reported seeing a tall, bounding figure "wearing a black cape, skintight pants, and quarter-length boots." For a few minutes he remained visible in the pecan tree into which he had jumped. He disappeared shortly before a rocket-shaped UF­O shot upward from across the street.