Term used by Sir William Barrett in his work On the Threshold of the Unseen (1917) to denote any mechanical means whereby communication from the unknown may reach us. The unknown may be an extraneous mind, living or dead, or the subconscious. The planchette, the ouija board, and the divining rod are typical autoscopes.
Barrett, William. On the Threshold of the Unseen. New York: E. P. Dutton, 1917.