premise: The Moberly–Jourdain incident (also the Ghosts of Petit Trianon or Versailles, French: "les fantômes du Trianon" / "les fantômes de Versailles") is a claim of time travel and hauntings made by Charlotte Anne Moberly (1846–1937) and Eleanor Jourdain (1863–1924).
hypothesis: The Moberly–Jourdain incident was written in the 1800s.
reason: It didn't say whether it was written in the 1800s or 1900s.