In Dai Vernon's Ultimate Secrets of Card Magic, 1967, p. 150, Vernon published the idea of tapping the deck on one corner to cause a corner-shorted card to jog from the edge. The idea was explained in more detail in The Vernon Chronicles, Vol. 1, 1987, p. 2, in which Vernon said he had learned the idea from a gambler in San Francisco. Ed Marlo, in his Advanced Fingertip Control, 1970, p. 64, writes that he had been using this technique “for years.” This came three years after Vernon had published the idea, yet Marlo did not mention it.