Ring Puzzle Once Owned by Olive C. Hazlett

This wire puzzle, a Chinese Nine Linked Rings Puzzle, belonged to Olive C. Hazlett (1890–1974). Hazlett was one of America's leading mathematicians during the 1920s. She taught at Bryn Mawr College, Mount Holyoke College, and the University of Illinois, after which she moved to Peterborough, New Hampshire. This and other of her puzzles and books of puzzles were collected from a community of Discalced Carmelite brothers who had lived in New Hampshire and who had befriended Hazlett there.

There is nothing on the puzzle itself that indicates when, where, or by whom it was made.

The object of a Chinese Linked Ring Puzzle is to remove all the rings from a bar with a long slot in it. Chinese references to unlinking linked rings go back over two thousand years. Although this type of puzzle is called a Linked Ring Puzzle, the rings are not directly linked. Rather, each ring is attached to a metal wire and the ring can be removed from the bar only when that wire no longer passes through the long slot of the bar. In the early 20th century this type of puzzle was often sold with two rings that could be slipped off the bar, as in this case; the normal starting position is when only one ring can be slipped off.

Except for the ring that will be removed first, each ring has the wire of an adjacent ring going through it. All of the wires are attached to a second, often much smaller, bar from which they cannot be removed. At least two well-known European mathematicians, Girolamo Cardano (1501–1576) and John Wallis (1616–1703), unsuccessfully tried to find an analysis that would yield the smallest number of steps it would take to remove all the rings in a puzzle as a function of the number of rings. A solution to that problem was known by the late 19th century. If the starting position has only one ring that can be slipped off, a linked ring puzzle with nine rings cannot be solved in fewer than 341 steps. The mathematics involved in the analysis is related to binary reflected codes, also known as Gray codes since they were described in Frank Gray’s 1953 patent involving coding of a message signal.

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