This is a method for making a genuine double knot, which is clearly tied in a rope, magically dissolve. It is described in the revised edition of Jacques Ozanam's Récréations mathématiques et physiques, 1723 (see p. 120 of Lori Pieper's English translation in Gibecière, Vol. 6 No. 1, Winter 2011). This disappearing knot has been erroneously attributed to the Italian-American magician, Ralph Chefalo (1885-1963), and has consequently come to bear his name.