“Double exposure ‘spirit’  photograph of girl standing, holding flowers, surrounded by spectral figures of three people],” G.S. Smallwood, 1905.

To celebrate Halloween, here are eight “spirit photographs” straight from the Library of Congress’ deepest, darkest crypt. Or, rather, their very convenient online database.

As Wendi Maloney explains at the Library’s blog, the general public was mystified by photography when it debuted in the mid-to-late-1800s. This meant unscrupulous rapscallions could dupe them into ghosts actually photo bombed in the afterlife. And these weren’t just gullible rubes who bought into the supernatural hype: respected folk like Sir Arthur Conan Doyle were about it, too.

All this hoopla outraged Harry Houdini. The magician had made it his life’s mission to debunk spiritualist charlatans, and took a hands-on approach to the matter. Maloney writes:

“To demonstrate how easy it was to fake a photograph, Houdini had an image made in the 1920s, showing himself talking with Abraham Lincoln. He even based entire shows around debunking the claims of mediums and the entire idea of spiritualism.”

That image is included in this gallery. It did not, however, completely debunk the spirit photo business.

Related: Check out a NY Times piece I wrote a long time ago about Memento Mori: turn of the century pics people took of dead loved ones.