According to the magician John Booth, Devant managed to fool a number of people into believing he had genuine psychic ability who did not realize that his feats were magic tricks. At St. George's Hall, London, he performed a fake "clairvoyant" act where he would read a message sealed inside an envelope. Oliver Lodge who was present in the audience was duped by the trick and claimed that Devant had used psychic powers. In 1936 Devant in his book "Secrets of My Magic" revealed the trick method he had used.