One black, howling wintry night in 1920 — just such a night when superstitious people would bar their doors and windows against marauding ghosts — Thomas Edison, the famous inventive wizard, gathered a small group of scientists in his laboratory to witness his secret attempts to lure spirits from beyond the grave and trap them with instruments of incredible sensitivity. Until recently only the few favored spectators ever knew the outcome of this sensational experiment. Only the few Edison intimates, assembled like members of a mystic clan, ever knew what unearthly forms materialized in the scientist’s laboratory that night to give proof or disproof of existence beyond the grave.
In a darkened room in his great laboratory, surrounded with beakers, generators, and other experimental equipment, Edison set up a photo-electric cell. A tiny pencil of light, coming from a powerful lamp, bored through the darkness and struck the active surface of this cell, where it was transformed instantly into a feeble electric current. Any object, no matter how thin, transparent or small, would cause a registration on the cell if it cut through the beam.
When the experiment was ready to begin the spiritualists in the group of witnesses were called upon to summon from eternity the etherial form of one or two of its inhabitants, and command the spirit to walk across the beam. Then while the spiritualists went through their rites the scientists watched intently the meter of the electric eye, which would flicker the instant any ghostly form interrupted the light beam.