Gizmodo on William Hope’s use of double exposure to create fake ghost images:
The results were spooky. Even knowing that they are fake, I look at them and feel the chills today. Imagine how it was back then. Even very smart people, like Sir Arthur Conan Doyle, bought into it. When Hope was exposed as a scam artist by the Society for Psychical Research, the writer defended him.
Cool, but indeed, very spooky.