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158 tell for certain which is the loop proper, i. e., the point at which the tape was doubled. (See Fig. 35.) The bystander is then requested to place the point of his penknife in the loop, but however careful he may be in his selection he will fail, as the performer is able to pull the tape clear of the knife in all cases. The secret lies in the fact that the tape is not folded exactly in half, one end being left shorter than the other by about three inches. When uncoiling the tape, if the knife be actually placed in the loop, and both ends are pulled from the point A, it will not come away; but if the short end be passed round to the left and both ends pulled from the point B, it will be found to come clear of the knife. All the performer has to do, therefore, is to watch and see if the knife is really placed in the loop or otherwise, and to act accordingly. The short end is carried round under cover of the fingers while twisting the tape.

Fig. 35 is arranged for clearness, but in actual practice the tape would receive many more twists, which would also be of a more intricate nature.