Edison's Menlo Park Laboratory, which was moved to the Henry Ford Museum in Dearborn, Michigan after his death, contained no prototype, models or plans for his telephone to the dead.

"I have been at work for some time building an apparatus to see if it is possible for personalities which have left this earth to communicate with us." - Thomas Alva Edison

As Spiritualism became a prominent religious movement between the 1840s-1920s, many scientists, psychical investigators and ghost hunters over the years toiled away in search of obtaining even the slightest proof of the existence of ghosts. From Tarot readings, seances and clairvoyance, the mysticism of the supernatural ran rampant throughout Western society with naysayers and physical researchers looking to demystify a movement that so captivated many.

In fact, the phenomenon had become so widespread that world renowned writers, scientists and inventors attempted to either debunk or prove the existence of ghosts. Among the curious was Thomas Alva Edison, the proclaimed "Wizard of Menlo Park". Considered by many to be a freethinker, Edison was a man who was no stranger to the skepticisms of divine interventions and the existences of higher powers, but on the subject matter had no qualms of toying with the notion of communicating with ghosts.

With psychic mediums conducting seances and claiming the ability to communicate with the dead, Edison reasoned that it could be a possible notion, albeit accomplished through the use of scientific means.

"I believe that if we are to make any real progress in psychic investigation," Edison once said during an interview. "We must do it with a scientific apparatus and in a scientific manner, just as we do in medicine, electricity, chemistry, and other fields."

The way Edison described such a device was that it would be so sensitive "that the slightest effort which it intercepts will be magnified many times" thus making it as valuable to the psychic researcher as the microscope was to the scientist. This device, which would be dubbed the "Telephone to the Dead" by paranormal researchers became what would have been Edison's final invention. With it, he proposed the use of a machine which could contact the dead and record their responses, based upon his belief that intelligence of all kinds existed throughout the universe, whether living or after death.

"I don't claim that our personalities pass on to another existence or sphere," Edison told Scientific American. "I don't claim anything because I don't know anything about the subject. For that matter, no human being knows. But I do claim that it is possible to construct an apparatus which will be so delicate that if there are personalities in another existence or sphere who wish to get in touch with us in this existence or sphere, the apparatus will at least give them a better opportunity to express themselves than the tilting tables and raps and Ouija boards and mediums and the other crude methods now purported to be the only means of communication."

With no blueprints, patents or designs remaining that would otherwise prove as evidence that such a machine was being created, Edison died on October 18, 1931, at the age of 84. Though, there have been multiple conspiracy theories surrounding the lore of Edison's "Telephone to the Dead", it was his basic theory and the legend surrounding its proposal that made him one of the great pioneers of paranormal investigations, particularly with the concept of EVP or "electronic voice phenomena" which was coined in the late 1950s using a two-way communication device known as a ghost box.

"I do hope that our personality survives," Edison said. "If it does, then my apparatus ought to be of some use."

Read more:

Telephone to the Dead: Myth or Fact? | Ghost Boxer