In March 1861, Boston jewellery engraver and amateur photographer William Mumler accidentally made a double exposure of a self-portrait, producing a photograph of himself in front of what looked like a floating, ghostly figure. Mumler realised two things: that the figure resembled his dead cousin, and that he had just struck gold.
At the time, spiritualism had a healthy following in the US and, before long, bereaved relatives of civil war soldiers would be desperate for contact with their dead sons and husbands. If Mumler could use photography, which many considered an empirical recording method, to create what looked like images of spirits, then he could make a fortune. So he went into business, charging $10 per photograph. Customers would pose as though they were sitting for their portrait; they would then be given a developed photograph of them with their "spirit extra". Both believers and the bereaved enthusiastically identified their lost loved ones in the images.
But sceptics soon noticed that some of the "spirits" resembled living Bostonians whom Mumler had recently photographed. In 1869, he moved his operations to New York, but he was arrested and tried for fraud. Mumler’s defence argued that he had simply captured reality; Mumler couldn’t be blamed if spirits were real. But the prosecution brought in other professional photographers who showed that Mumler could have easily used double exposure to create the "spirits".
Ultimately, the charges were dropped because of lack of evidence. Mumler moved back to Boston, his career in decline. But by the time he died in 1884, he had already spawned countless imitators, both in the US and abroad. Spirit photography was to remain popular for years to come, attracting famous supporters such as Sir Arthur Conan Doyle and surging in popularity during the first world war as soldiers’ relatives once again tried to contact their dead loved ones. And although spirit photography may now be out of vogue, paranormal investigators persist in trying to use their cameras to prove the existence of a pantheon of unexplained phenomena, from ghosts to UFOs to Nessie.