The so-called Mercury Card Fold into fourths, which is executed underneath the deck with both hands, gets its name for its appearance in the effect “Mercury's Card” in Jean Hugard and Fred Braue's Expert Card Technique, 1940, p. 303. It was however already described by Frank Chapman in Six Bits, 1936, in a card to matchbox effect called “A Sure Bet”. Chapman writes that he does not know the originator of the effect and he does not claim the folding technique, which is also uncredited in Expert Card Technique. However, in The Fred Braue Notebooks, Volume 3, 1985, p. 3, Braue credits the move to John Scarne.

A one-handed folding method to fold a card into fourths was described by William H. McCaffrey in his “Cash and Change-Purse” from The Sphinx, Vol. 37 No. 5, July 1938, p. 113. The same technique was also briefly described in “A Card Mouthful”, “a favorite with John Scarne”, in John Northern Hilliard's Greater Magic, 1938, p. 308.

A one-handed folding method into sixths from classic palm position was also described in Expert Card Technique, 1940, p. 305, as “Folding a Card” with the note that this technique “is preferred by some performers”.

• Category in Denis Behr's "Conjuring Archive"