The Davenport Cabinet is an illusion created in the late 19th century by the Davenport Brothers of Rochester, and was subsequently used in their séance shows. The brothers' early shows required them to extinguish all lights in the house where they performed, so that they could maneuver rope and props in darkness, claiming that spirits were performing the tricks. Naturally, this deception was not entirely convincing, and the Davenport brothers returned to their home in Rochester to develop a better method.
Out of this experimentation came the Davenport Cabinet, a basic wooden cabinet large enough for both brothers to sit within, often with a volunteer audience member joining them. More info here: PrairieGhosts.com and the Davenport Brothers page.