O'Key Sisters, Jane and Elizabeth (ca. 1838)

Two somnambules or hypnotized subjects of John Elliotson, an early British experimenter in animal magnetism. The two girls were supposedly put into a trance by passes on the part of Elliotson and two different states induced: a condition of coma with insensibility and lack of consciousness, and ecstatic delirium in which they spoke, sometimes making clairvoyant predictions and also being subject to the operator's suggestions. In the ecstatic condition, which occasionally lasted for days, one of the girls claimed to be able to see with the back of her hand.

After many "successful" demonstrations, Elliotson one day met with a complete failure, which excited his opponents to accusations of imposture on the part of the girls. Elliotson was stigmatized as a weak and credulous man. Eventually he was obliged to resign his position as physician at University College Hospital, London. However, Elliotson persisted with his experiments and published his conclusions in an appendix to his textbook Human Physiology (1840) in which he detailed his further experiments with the O'Key sisters.