The belief in paranormal occurrences with ghosts and other unexplained phenomena is by no means a modern concept. Such beliefs have waxed and waned throughout recorded history. In the nineteenth century, three sisters in New York unwittingly created the Spiritualist Movement through their alleged contact with the spirit world.

From Wikipedia:

The Fox sisters were three sisters from New York who played an important role in the creation of Spiritualism, the religious movement. The three sisters were Leah Fox (1814–1890), Margaret Fox (also called Maggie) (1833–1893) and Kate Fox (1837–1892). The two younger sisters used "rappings" to convince their much older sister and others that they were communicating with spirits. Their older sister then took charge of them and managed their careers for some time. They all enjoyed success as mediums for many years.

In 1888 Margaret confessed that their rappings had been a hoax and publicly demonstrated their method. She attempted to recant her confession the next year, but their reputation was ruined and in less than five years they were all dead, with Margaret and Kate dying in abject poverty. Spiritualism continued as if the confessions of the Fox sisters had never happened. "This pattern of confession followed by retraction, which is not uncommon, has supplied both true believers and sceptics with material to support their case, so controversy never ends."

It is no surprise that the desire to communicate with the dead reached a fever pitch during the Civil War due to the high casualties in both the Union and Confederacy. People needed to have their last goodbyes and sought comfort in any way they could. It became highly fashionable to hire mediums to come to gatherings in homes or public venues for this specific purpose. Unfortunately, most of the alleged mediums, like the Fox sisters, were charlatans looking to profit from the grief of others. The fraud has continued into the twentieth and twenty-first centuries and the reputations of legitimate mediums have never fully recovered.

Seances involved people sitting around a table with their eyes closed asking the spirits to communicate through the medium present. Often the alleged medium had the table rigged with different things under tables such as bells with strings that they could pull with their toes, chalkboards on which they could write messages with their toes, and so on. While people's eyes were closed, the clean chalkboard was quickly and quietly switched with the chalkboard containing the message from the great beyond. Tables were also rigged to shake and jerk at the best dramatic moment, which was allegedly a sign from the spirits with the people. The belief in false mediums went to the highest levels of society, including Mary Todd Lincoln, who held seances in the White House after her son died. She also went to a spirit photographer in the years after President Lincoln was killed in order to try and make contact with him.

Spirit photography became immensely popular in the mid-to-late nineteenth century but it was also the most fraudulent practice by these charlatan mediums. It was very easy to accomplish by taking a normal photograph of a living person and then developing it with a double exposure method to impose another image on top of it.

Here are some examples of spirit photography.