Welcome to the first part of a puzzlingly exciting new series of blog posts, written by Andrew Rhoda, the Lilly Library’s Curator of Puzzles!
Here at the Lilly Library, we have the Jerry Slocum Mechanical Puzzle Collection. The collection consists of over 35,000 mechanical puzzles in addition to the over 5,000 books that Jerry collected along with his puzzles. The collection also contains over 170 boxes of manuscripts that Mr. Slocum has collected along with the puzzles. This manuscript collection has Jerry’s research for his puzzle collecting and the research for his book writing as well.

Image of Slocum Room puzzle exhibition cases at the Lilly Library.
A question that comes up when I talk with people finding the collection for the first time is, “What is a mechanical puzzle exactly?” When most people think of a “puzzle,” they think of crosswords or jigsaw puzzles. Mechanical puzzles are slightly different.
Jerry developed a definition that he includes in one of his early books that he wrote with Jack Botermans, Puzzles Old and New: How to Make and Solve Them. In that book the definition reads, “A mechanical puzzle is a self-contained object, composed of one or more parts, which involves a problem for one person to solve by manipulation using logic, reasoning, insight, luck, and/or dexterity” (Slocum et al. 1986, 4).
The most recognizable mechanical puzzle for most people is the Rubik’s Cube. These mechanical puzzles are also sometimes known as “brainteasers,” which may be familiar. Mechanical puzzles take many different forms, which Jerry categorized by what the solver has to do to solve the puzzle.
He did this as solutions are a common denominator to all puzzles: all puzzles have a solution by necessity. “A puzzle without a solution,” Jerry once told me, “is just a paperweight.” With that in mind, Jerry used that common feature to group puzzles into categories.
Jerry settled on ten categories of mechanical puzzles. The categories, as we have them in the Slocum Mechanical Puzzle Database, are:
- Put-together
- Take-apart
- Interlocking
- Disentanglement
- Sequential Movement
- Dexterity
- Puzzle Vessels
- Vanish Puzzles
- Folding Puzzles
- “Impossible” Puzzles
The categories one through six have sub-categories to further group the types of solutions that appear in the larger categories. When referenced, you can call puzzle by their category/sub-category number (1.1, 1.2, 1.3, etc.) in addition to a descriptive title (two-dimensional put-together, three-dimensional put-together, miscellaneous put-together, etc.).
Occasionally, a puzzle could be included in more than one category. There are puzzles that ask you to disentangle a part of puzzle, but to do that it could require a sequence of movements. A good example of a puzzle that does that is a puzzle commonly called the “Chinese Rings” or the “Baguenaudier,” which is pictured here.

A six-ring version of the “Chinese Rings” puzzle, made by Uncle’s Puzzles.
An argument could be made that this puzzle should be either a disengagement puzzle or a sequential movement puzzle. Since a good argument could be made for either category, Jerry just placed the puzzle in both categories. Jerry saw his categorization system as an aid in defining puzzles but were inclusive of other categories. You will see this in the catalog of the collection, the Slocum Mechanical Puzzle Database. Some puzzles have two, or more, categories listed on their records.
The goal that Jerry had with his categories was to have a way to group puzzles with similar solutions together into categories. That way he would have a way to reference his personal collection and a reference point for describing puzzles in his books. In fact, Puzzles Old and New: How to Make and Solve Them book mentioned above, categorizes the puzzles featured using Jerry’s categorization system and includes examples of puzzles from each of the categories and sub-categories. This book presents the categories in a different order than the list above.

Image of Slocum Room puzzle exhibition cases at the Lilly Library.
The exhibition in the Slocum Room also follows this system to illustrate the variety of mechanical puzzles in the collection at a glance. We also have hands-on puzzles available in the Slocum Room for visitors to solve to see what mechanical puzzles are like first-hand. More information on the collection can be found on the Lilly’s website at https://libraries.indiana.edu/lilly-library/mechanical-puzzles.
The collection is available for visitors to see in our Reading Room by emailing our Teaching & Research department at liblilly@iu.edu. We also have a Puzzle Tour on Fridays at 1:00pm that includes information about the collection, a tour of the Slocum Room exhibition, and a selection of puzzles from the full collection.
About the author: Andrew Rhoda is the Curator of Puzzles at the Lilly Library, where he oversees the 35,000 mechanical puzzles in the Jerry Slocum Mechanical Puzzle Collection, in addition to the Slocum book and manuscript collections. He hosts classes from across disciplines who visit the collection, and he has presented on mechanical puzzles and the collection at puzzle events here in Bloomington and around the world.
Bibliography
Slocum, Jerry and Jack Botermans, Carla von Splunteren, Tony Burrett, and Jerry Slocum. Puzzles Old and New: How to Make and Solve Them. Plenary Publications International (Europe), 1986.
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