See “Spooner's Specialty Force” in Wonderful Routines Of Magic by Ellison Poland, 1969, pp. 51-53. U. F. Grant also published this idea somewhere. David Britland has located what may be the earliest example of this idea: “It Worked” by Alfred Frangleton, in Magic Wand, Vol. XXXI, Oct./Nov. 1942, No. 195, p. 153. Frangleton's idea was quite advanced in concept. He tied a thin invisible thread around the block, so that after the cut and force he could spread the block, breaking the thread and leaving the deck unprepared. Michael Weber, in “Sutured Incision” in Pengrove Connection, 1983, pp. 4-5, used four small threaded blocks to achieve a Spectator Cuts the Aces effect.