Taking the idea of the telephone and the telegraph a bit further, Edison announced in October of 1920 that he was working on a machine to open the lines of communication with the spirit world. In the aftermath of World War I, spiritualism was undergoing a revival, and many people hoped science could provide a means to access the souls of the recently deceased. The inventor, himself an agnostic who admitted he had no idea if a spirit world even existed, spoke of his quest in several magazines and explained to The New York Times that his machine would measure what he described as the life units that scatter through the universe after death.
Edison corresponded with British inventor Sir William Crookes, who claimed to have captured images on "spirit photographs." These photos allegedly encouraged Edison, but he never introduced any machine that he said could communicate with the dead, and after his own death in 1931, no machine was found. Many people believe he was just playing a joke on the reporters he'd talked to about his "spirit phone."
Some people claimed that at a séance in 1941, Edison's spirit told the participants that three of his assistants possessed the plans. The machine was reportedly then built, but did not work. Later, at another séance, Edison supposedly suggested some improvements. Inventor J. Gilbert Wright was present and worked on the machine until his own death in 1959, but, as far as we know, never used it to contact spirits.