Though he gained fame as a magician and escape artist, Harry Houdini, born Erik Weisz, was also a well-known skeptic of spiritual practices. After his mother died in 1913, he tried to contact her through a medium at a séance and saw through the medium's sleight-of-hand tricks. He launched a public campaign against so-called mystics. His 1923 book, A Magician Among the Spirits, accused mediums of defrauding grieving people and explained how common séance illusions were performed. He put his stage show on hold that year to go on a lecture tour supporting the book. By 1925, he was offering $10,000 to any medium whose tricks he couldn't figure out. He never had to pay up. Which of the following words from the passage indicates a sequence of events?