In March 1848, two young sisters in Hydesville, New York came up with what they may have considered a fun prank. Teenager Maggie Fox and her younger sister Kate claimed that there was a spirit communicating with them by making otherworldly raps on the walls and furniture of their house. When their mother asked how many children she’d had, the spirit appeared to rap out the correct number. One of their neighbors reportedly witnessed these sounds, and word spread that there was something strange going on at the Fox house.

Maggie and Kate made these noises by cracking their knuckles, toes and other joints—a fact Maggie confessed to the New York World 40 years later, in 1888. By that point, the childhood prank had spun out of control, and the now adult sisters had become famous mediums. The Fox sisters and their public séances helped spark a spiritualism craze in the United States and Europe built on the belief that it was possible for living humans to communicate with the dead.

Soon after Maggie and Kate’s supernatural discoveries, the girls went to live with their older sister Leah in Rochester. When the supernatural occurrences continued, Leah “decided to turn this into a little bit of a business,” says Nancy Rubin Stuart, author of The Reluctant Spiritualist: The Life of Maggie Fox.

In November 1849, at Rochester’s Corinthian Hall, Maggie and Kate demonstrated their powers to a paying crowd of nearly 400 people. Newspapers began to report on the girls, and the sisters soon held public demonstrations in New York City.

Plenty of people denounced the girls as fakes—and some correctly guessed that the sisters were just cracking their joints—but many others believed that they were witnessing a true spiritual phenomenon. Soon, other people began to open their own shows in which they claimed to be “mediums” who could communicate with the dead.

One of the key aspects that differentiated the spiritualism craze from religious and spiritual beliefs that came before it was its connection to the growing media and entertainment industries in the United States and Europe. People in the business of spiritualism gave paid theatrical performances featuring elaborate lighting, music and table-tipping séances. The Fox sisters became celebrities, and so too did other self-proclaimed mediums.

In the 1850s, Ira and William Davenport became famous for what was essentially a magic show whose tricks they attributed to spiritual intervention. Many stage magicians differentiated themselves from spiritualists like the Davenport brothers by exposing what spiritualists did as a hoax (something for which illusionist Harry Houdini later became famous). Despite these exposures, spiritualism remained extremely popular throughout the 19th century.

Not everyone who attended spiritualism shows believed what they were seeing. Some went as skeptics who wanted to see for themselves if there was anything convincing about what the Fox sisters or other mediums did. Some attendees may have gone simply for the entertainment value. Yet for many people, demonstrations of spiritualism were not only believable, but deeply comforting.

During and after the Civil War, many Americans found solace in the idea that they could communicate with the people they’d lost. One of these people was Mary Todd Lincoln. During Abraham Lincoln’s presidency, the first lady held séances in the White House to try to communicate with her dead children.

The spiritualism craze also found many followers in Europe. After the death of Queen Victoria’s husband, Prince Albert, in 1861, the queen held many séances in Buckingham Palace in order to talk to him.

Maggie’s confession to the New York World in 1888 that her and her sister’s communication with the dead had been a hoax—as well as her public demonstration of how she cracked joints to make “rapping” noises—was big news among people interested in spiritualism.

At the public demonstration, attended by Kate and held shortly after the publication of Maggie’s confession, the New York Herald reported that Maggie “was greeted with cheers and hisses.”

“When I began this deception I was too young to know right from wrong,” Maggie told the crowd, according to the Herald. “That I have been mainly instrumental in perpetuating the fraud of Spiritualism upon a too-confiding public, many of you already know. It is the greatest sorrow of my life.”

Yet for believers, the news was not necessarily a blow to spiritualism’s credibility.

“There are a lot of situations in which spiritualist mediums were caught faking, committing fraud, or spiritualist mediums made declarations similar to [Maggie’s confession],” says Simone Natale, a professor at the University of Turin in Italy and author of Supernatural Entertainments: Victorian Spiritualism and the Rise of Modern Media Culture. “But these never really stopped people from believing it."

It isn’t clear what motivated Maggie to confess that it had all been a hoax in 1888, nor is it clear why exactly she recanted that confession the next year. Regardless of Maggie and Kate’s true feelings about their careers as mediums, the spiritualist craze they had unwittingly helped start continued to be popular well into the 20th century.