“The Prisoners’ Release Puzzle”

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Take two pieces of string or tape, and round the wrists of two persons tie the string, as shown in Fig. 19. It adds to the amusement of the puzzle if one of the persons is a lady and the other a gentleman. The puzzle is for them to liberate themselves, or for any one else to release them without untying the string. To do this, B makes a loop of his string pass under either of A’s manacles, slips it over A’s hands, and both will be free. Reverse the proceeding, and the manacles are again as before.

Cassell’s Complete Book of Sports and Pastimes, 1896