was equated with the bogeyman, as a means of scaring children into behaving by telling them if they were not good, Spring-heeled Jack would leap up and peer in at them through their bedroom windows, by night. However, it was in fictional entertainment where the legend of Spring-heeled Jack exerted the most extensive influence, owing to his allegedly extraordinary nature. Three pamphlet publications, purportedly based on the real events, appeared almost immediately, during January and February, 1838. They were not advertised as fiction, though they likely were at least partly so. The only known copies were reported to have perished when the British Library was hit during The Blitz, but their catalog still lists the first one. The character was written into a number of penny dreadful stories during the latter half of the 19th century, initially as a villain and then in increasingly heroic roles. By the early 1900s he was being represented as a costumed, altruistic avenger of wrongs and protector of the innocent, effectively becoming a precursor to pulp fiction and then comic book superheroes. Theories No one was ever caught and identified as Spring-heeled Jack; combined with the extraordinary abilities attributed to him and the very long period during which he was reportedly at large, this has led to numerous and varied theories of his nature and identity. While several researchers seek a normal explanation for the events, other authors explore the more fantastic details of the story to propose different kinds of paranormal speculation. Sceptical positions Sceptical investigators have dismissed the stories of Spring-heeled Jack as mass hysteria which developed around various stories of a bogeyman or devil which have been around for centuries, or from exaggerated urban myths about a man who clambered over rooftops claiming that the Devil was chasing him. Other researchers believe that some individual(s) may have been behind its origins, being followed by imitators later on. Spring-heeled Jack was widely considered not to be a supernatural creature, but rather one or more persons with a macabre sense of humour. This idea matches the contents of the letter to the Lord Mayor, which accused a group of young aristocrats as the culprits, after an irresponsible wager. A popular rumour circulating as early as 1840 pointed to an Irish nobleman, the Marquess of Waterford, as the main suspect. Haining suggested this may have been due to him having previously had bad experiences