You may then produce two more spools, or wooden balls, and place one of them over the ends at A, and the other over the ends at B.
Fig. 15.
The following will then be the appearance of the balls or spools and the tapes passed through them (Fig. 15):
You may move about the spools 2 and 3, to show how the tape runs through them, but you must not move spool 1.
You may then say that the puzzle is to get the spools off the tapes while the four ends are held firmly in the hands of four persons. Appoint four persons to hold them, and you may then say: “To make doubly sure, I will tie one of the ends at A to one of the ends at B with (the first half of) a knot.” It does not signify which ends you take to do this, so that you take one A and one B. “I will now pull these two ends so tight that it will draw the three spools together, and also tighten all along one side of them.”
Fig. 16.
Then, while four persons hold firmly the extreme ends of the tapes, you must take shorter hold of the two A’s with your left hand, (where it is marked by a dotted line, Fig. 16,) and also take hold of the other tapes where a dotted line is marked on them towards B. Then drawing your arms wider apart, so as to pull the tapes steadily, the spools or balls will fall to the ground without passing over the ends of the tapes.