This is the invention of Marcello Truzzi, which he contributed to Magick, No. 184, 1977, pp. 918-920. In Magick, No. 402 Joe Bernasconi claimed that Dunninger did this trick in a Coney Island tent show during W.W. II. Minch questioned this in Spectacle and no corroborative evidence has to date surfaced to support Bernasconi's assertion.