"Psychical researcher Hereward Carrington who visited Keeler at Lily Dale in 1907 caught him cheating by substituting slates commented "for not only did I see Keeler make the exchange, but the slates I received at the conclusion of the seance were different from those I examined... Keeler is a clever trickster, and the degree of perfection he has attained certainly seems to indicate that he must have been in the habit of practising these tricks continuously for a number of years."