<P> Magician Les Arnold is reported to have been the first to have devised a clear box sawing (known as the "Crystal Sawing") as far back as 1976 . The Pendragons performed a variation called "Clearly Impossible", in which the box used is both particularly slim and also transparent . The concept of "Clearly Impossible" has been credited to Jonathan Pendragon and the major distinguishing feature of The Pendragons' illusion from the Les Arnold concept is that the transparent boxes are seemingly never covered . </P> <P> The "double sawing illusion" is a way of adding an extra effect to box - type sawings . It is generally associated with the "thin - model" sawing apparatus . The magician saws two people in half using two sets of apparatus . The people are usually chosen or dressed so as to be clearly distinguishable . For example, they might be in different colored costumes, of different skin colors, or of different genders . After the box halves are separated they are jumbled up and then re-assembled so that the bottom half of one box is matched to the top of the other and vice versa . When the victims emerge, each appears to have been given the other's lower half . </P> <P> The creation of this version has been credited to magician Alan Wakeling, who devised it for fellow magician Channing Pollock to perform . </P> <P> An assistant lies down on a table . A frame is placed over her middle . The magician then presents an electric jigsaw and proceeds to align the blade into a slot in the frame . The magician switches on the saw and apparently uses it to slice through the assistant's waist, which remains obscured by the frame . The saw emerges from the opposite side of the frame . Once the sawing is finished the frame is removed and the assistant is revealed to be in one piece . </P>

How does the illusion of sawing someone in half work