Welcome to the seventh spotlight of the Lilly Library’s Mechanical Puzzle blog series, written by Andrew Rhoda, the Lilly Library’s Curator of Puzzles!
Puzzle vessels are objects where the solver drinks from, pours from, or pours into the vessel without spilling or otherwise losing the contents of the container. As Puzzles Old and New: How to Make and Solve Them puts it, “The trick in drinking from puzzle jugs or glasses is not to spill the contents. These vessels have a lattice or a series of holes around the top and the liquid spills if you try to drink in a conventional manner. The trick is to discover a hidden or disguised tube which is then used like a straw to such the liquid out. The remaining holes are covered with the fingers” (Slocum et al. 1986, 141). Some of these vessels have hidden openings to fill the vessel; some have secret straw mechanisms that you use to drink, and some may just pour out the contents of the cup onto you if you are a bit too greedy.
It should also be noted that the puzzle vessel category is the first of the Slocum classifications that do not have separate sub-categories, officially, and is the case going forward. This is not to say that the puzzles in these categories cannot be grouped together within the categories. However, the similarities tend to be broader than previous categories and fewer in number, which is why these later categories are not further divided.
Examples of Puzzle Vessels
One common type of puzzle vessel is the “justice cup” puzzle vessel. The goal with this puzzle is not to pour too much into the cup. If you do, the cup punishes you for your greed, and the entire cup will drain out of the bottom of the cup, either onto you or into the base of a saucer, depending on the puzzle. Joseph Greenwood and Bennet Woodcraft in The Pneumatics of Hero of Alexandria, illustrate the version of this mechanism described by the first century Greek mathematician and engineer, Hero of Alexandria (Hero 1851, 27). A secondary goal is to figure out what makes the cup drain if filled too full and to fill it just full enough not to drain.
The example shown here is a modern version of the justice cup with saucer made by the Yaozhou Kiln in China in 1998. Yaozhou is known for its “celadon” pottery with the Grove Art Online encyclopedia noting, “The Yaozhou kilns gradually developed a fine green-glazed ware, adopting many of the stylistic and even technical characteristics of the Yue wares: for example, extra iron oxide was added to the clay to produce a darker gray body than was normal in the almost white clay of the north” (Kerr et al. 2023). The same article notes that cups with stands are a form that Yaozhou ceramics were known to take (Kerr et al. 2023). As a side note, in another article, Gordon Campbell notes that the term “celadon” is a “European term for a type of Chinese stoneware also known as greenware; the name derives from the colour of the dress worn by the shepherd Céladon in the stage version of Honoré d’Urfe’s 17th-century pastoral romance, L’Astrée” (Campbell 2009).
Another type of puzzle vessel is commonly called the “puzzle jug.” The goal is simple: just drink from the jug. To complicate matters, these jugs have perforations or holes just under the lip of the jug, as noted before. They also usually have holes all around the lip of the jug, occasionally on the handle as well. Here you must plug the holes on the lip and/or handle and then use one of the holes as a straw (Slocum et al. 1986, 141). These jugs would sometimes include short, funny poems to add to the pressure to the hapless imbiber. The example pictured here is a salt glazed stoneware jug, a technique of glazing pottery that originated in Germany but was later introduced to Great Britan (Clark 1995, 33-34).
A unique inclusion in the category is a specific type of “tea pet.” Tea pets are a part of traditional Chinese tea culture. Usually, these tea pets are small clay figures made of unglazed clay that during the tea service will have water or tea poured over them. Over time these figures gain a patina from the tea that are poured over them (Lee and Attinger 2016). The figures generally take the shape of animals, although they may also take the form of people or mythological figures.
A subset of these tea pets has another function as part of the tea set. These tea pets are first submerged in cold water before being placed on the tea tray. When the hot tea or water is poured over them, a tea pet like the one pictured here will “spit” the water out. Lee and Attinger indicate in their paper “Thermodynamics and Historical Relevance of a Jetting Thermometer Made of Chinese Zisha Ceramic” that these “jetting” tea pets were used as thermometers to demonstrate when the water was the correct temperature to brew the tea (2016). This article also explains the mechanism of the jetting thermometer tea pet (Lee and Attinger 2016). From a puzzle perspective, figuring out where the water will come from is part of the puzzle, the other part being the ability to demonstrate how the mechanism works for others.
If you are interested in seeing more of the puzzle vessels that are part of the Slocum Puzzle Collection you can at https://libraries.indiana.edu/lilly-library/mechanical-puzzles. You can also attend the Friday Puzzle Tour held from 1:00pm to 2:00pm in the Slocum Room to learn more about the 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
Campbell, Gordon. “Celadon.” Grove Art Online. 9 Nov. 2009; Accessed 9 Apr. 2026. https://www.oxfordartonline.com/groveart/view/10.1093/gao/9781884446054.001.0001/oao-9781884446054-e-7002071326.
Clark, Garth. 1995. The Potter’s Art: A Complete History of Pottery in Britain. Phaidon Press Ltd.
Hero. 1851. The Pneumatics of Hero of Alexandria: From the Original Greek. ed. Bennet Woodcraft, trans. Joseph George Greenwood. Taylor, Walton and Maberly.
Kerr, Rose, Regina Krahl, Margaret Medley, Yutaka Mino, Bent L. Pedersen, Laurence Chi-Sing Tam, Mary Tregear, S. J. Vainker, and Nigel Wood. 2023. “China: Ceramics.” Grove Art Online. 10 Oct. 2023; Accessed 9 Apr. 2026. https://www.oxfordartonline.com/groveart/view/10.1093/gao/9781884446054.001.0001/oao-9781884446054-e-90000371729.
Lee, Vincent and Attinger, Daniel. 2016. “Thermodynamics and Historical Relevance of a Jetting Thermometer Made of Chinese Zisha Ceramic.” Scientific Reports, 6. 28609. Accessed 9 Apr. 2026. https://doi.org/10.1038/srep28609.
Slocum, Jerry and Jack Botermans, Carla von Splunteren, and Tony Burrett. 1986. Puzzles Old and New: How to Make and Solve Them. Plenary Publications International (Europe).
Leave a Reply