The introduction sets out the historiographical framework and principle approaches of the book.Studies of nineteenth and twentieth century interactions between the established sciences and psychical phenomena have yielded many important insights but left many questions unanswered.We know a good deal about the psychical interests and investigations of a handful of scientists but only a partial sense of how far their examples were followed.We know a lot about the ‘occult’ uses to which spiritualists, theosophists and other occultists put developments in physical sciences relating to ether, energy, electricity and matter, but far less about the uses to which scientists made of psychical and occult phenomena in their scientific enquiries.Existing studies have also established much about the connections between ’physics and psychics’ at the level of ideas, theories and concepts, but have largely sidestepped the experimental nature of these connections.