Place a bust on a pedestal in the corner of a room, and let there be two tubes, one of which goes from the mouth, and the other from the ear of the bust, through the pedestal and floor, to an under apartment.

Then if a person be placed in the under room, by applying his ear to one of the tubes as soon as a proper signal is given, he will hear any question that is asked, and can immediately return an answer; and if wires be contrived to go from the under jaw and eyes of the bust, they may be made to move at the same time, and by these means appear to deliver the answer.

It was by a contrivance of this kind, that Don Antonio de Moreno so much astonished the celebrated Knight of the Woeful Countenance, and his facetious squire Sancho Panza, by resolving certain doubts proposed by the former concerning his adventures in the cave of Montesinos, and the disenchantment of my lady Dulcinea.