The Sideric Pendulum is an obscure pamphlet or article about a unique divination tool – a pendulum used for psychic communication – which includes an introductory note by Arthur Conan Doyle. In this piece, Doyle introduces the concept of the "sideric pendulum," explaining that spiritualists have employed it as a medium of communication with the unseen. The pendulum, typically a weighted object on a string, is said to swing in response to questions (for example, circling or swaying to indicate yes/no or spell out messages), potentially guided by spirits or the user's own subconscious psychic ability. Doyle likely recounts a specific anecdote: how a pendulum helped locate a lost item or answered a perplexing question, causing a stir in the press. His introduction endorses the pendulum's validity as a simple yet powerful psychic tool, framing it as part of the repertoire of spiritualist practices. The main content, possibly authored by someone else, would detail instructions and testimonies about using the sideric pendulum. Doyle's involvement lent credibility and publicity to this modest publication. The Sideric Pendulum serves as a fascinating footnote in Doyle's work – evidence of his willingness to explore even the small, homey methods of divination in his quest to normalize communication with the beyond.