How did early photographers remember the dead? They took photos with ghosts

It all started by a fluke.

Boston metal engraver William Mumler was learning how to photograph in the 1860s, not long after the invention of the camera when one day, he noticed that in one of his developed self-portraits, there was a strange girl-like figure sitting in the chair next to him.

He didn't know how she got there. But he was convinced it was a ghost — "the soul of a dead girl," Peter Manseau explains.

Manseau, a curator at Washington's National Museum of American History, said Mumler's discovery marked the start of spirit photography. It's the topic of his new book, The Apparitionists.

"He thought he had made a mistake," he said of Mumler. "He thought perhaps that he hadn't cleaned the glass plate properly on which the photograph was made."

Tapping into grief

It was a mystery. And in it, Mumler saw a business opportunity.

The American civil war was well underway, and hundreds of thousands were killed. Mumler tapped into this grief, hawking the photos as a way to reconnect with the dead.

It became a lucrative business.

"He sells solace at a time when it is terribly needed and he makes this claim that this is something new that technology is able to do for humanity," Manseau explains. "Something that has never been possible before, but now, thanks to photography, it is possible."

In one of his most famous spirit photos, he claimed to have captured the ghost of Abraham Lincoln, towering above his widow Mary Todd Lincoln.

When some in Boston thought he was a scam, he moved to New York, where he was arrested for fraud in 1869. He was put on trial but no one was able to prove exactly how he did it. So he walked free.

His photography career dwindled before his death in 1884.

'New way of holding on to faces'

Over the years, Mumler insisted he didn't know why ghosts showed up in his photos.

But Manseau thinks it was done using double exposure, given photography was glass plate-based at the time.

"It seems that he was able to make an image on the glass before he took the photo, and then exposed the glass again with the image of his portrait sitter, his client."

Though the photos have since been proven a hoax, Manseau said it's important to remember just how "miraculous" it must have seemed at the time.

"It provided this new way of holding on to faces which I think drastically changed human memory. It drastically changed human relationship with loss," he said. 

"The possibility of holding on to faces meant that people lived on in a way that they had never lived on before, in the imagination, in the memory. Those are not little things. Those were very significant."