Roman Dodecahedra of Unknown Function

Posted by Chris Parker
Oct 18 2005

Mathematics Today: December 2004

“While I was a guest at the Max Planck Institute for Mathematics in Bonn during the summer of 2004, I came across the following interesting Roman item:

Figure 1: Roman dodecahedron from the Rheinisches Landesmuseum Bonn

This is a Roman dodecahedron made of bronze, dating from the 2nd or 3rd century A.D., which was found in the vicinity of modern Bonn. It has small spherical objects at each of its vertices, and at the centre of each of its faces is a circular hole. Also on the faces are small circles, arranged in the shape of a pentagon around the circular hole.

About 100 of these curious objects have been found, from England in the north and Hungary in the east to Italy, with the greatest number discovered in the west of Germany and in France. They appear in various contexts, and have been constructed of several materials, such as bronze and stone.

No-one knows what they were used for. They are never mentioned in contemporary literature and do not appear in any surviving pictures of the time. Various conjectures exist as to their use, from being used to calibrate the size of water pipes, through candle holders (wax was found in one of them) to army parade standard bases, however, the most widely-held theory is that they were religious artefacts of some sort, possibly used in rites derived from Celtic sources. This last hypothesis has been suggested because the dodecahedra have mostly been found in Gallo-Roman sites.

There are some references available in the archaeological literature, such as ; the standard book reference is , which is in Flemish with a French summary, and a slightly newer treatise is , which is in German (although many of the facts in this book are summarised in Artmann’s book on Euclid . One of the few recent references in the mathematical literature (which is in English) is a short note which is also by Artmann .

5 Responses

  1. B Campbell says:

    Some 20 years ago while diging in my rear garden north of Romford, England I came across a Roman Dodecahedra. At the time I had no idea what I had found until some years later I saw one displayed in a Roman Fort Museum outside Frankfurt, Germany. I subsequently took the item to the British Museum, where I was told it was either a fake or one of the best examples of a Roman Dodecahedra found to date. I, of course, know it to be genuine in as much as I discovered it when removing a tree stump and buried perhaps two feet down… I still have the Dodecahedra and can supply photographs and dimensions upon (reasonable) request..

  2. Administrator says:

    Dear Campbell,

    We’d love to see photos. Any idea from holding one in your hands what they might have been used for?

  3. B Campbell says:

    Hello, It is great that someone has an interest in these objects. I have to say I was very disappointed by the response I had from British Museum staff, although to be fair they were working in temporary accomodation during renovations to the Museum when I visited them. It is strange you say “holding one in your hands” as it is about that size. I have always wondered about the little ‘mushroom’ pegs or legs, as they appear to me to be important, not just left over from casting the metal. My theory before I knew the artefact to be Roman was that it was a plumber’s form for checking the diameter of pipes. Each hole/bore is a different diameter, ten are beautifully formed, each with three concentric furrowed around them, while the remaining two, which might be described as top and bottom, are more roughly formed, with no concentric circles. The bottom/base one in my orientation being the largest diameter bore, the top one being slightly smaller in diameter, but both larger in diameter than any of the ten others. I believe for this reason some have speculated the dodecahedra might have been impailed upon a stake, pike or staff. Returning to the pegs, which appear to have been purposely shaped into ‘mushrooms’, I can see in my minds eye it covered in a leather jacket, the pegs being pressed through eyelets to hold the covering in place.. Maybe fanciful on my part as the dodecahedra is truly a lovely piece of art-form, fuctional or not. I am not certain how I go about providing pictures for display here and I would welcome your advice. I hope my brief, and quick, description is helpful. My Dodecahedra is made of bronze I believe and of a brown coppery colour, it truly is magical and fascinating!

  4. Administrator says:

    Dear B.

    You can e-mail the photos to s8intcom@comcast.net I would set up a new page for the photos incorporating this intitial post topic and perhaps this description. If you want to leave contact info for yourself, we could encourage, anyone with answers or questions to contact you.

    Since metal can’t be dated they may not even be Roman. Maybe the Romans found them. Even for your guestimated uses they seem to be very turned out and needlessly artisitic.

  5. B Campbell says:

    Thank you… I will e-mail photos as requested.. I have read that these Dodecahedra may be Druidic in origin and seized by the Romans during their occupations. I find this difficult to believe. For if their value to the Druids was as important as has been speculated, I would have expected the Druids to have secreted them away and at least some to have been found in places other than those occupied by the Roman Legions. That said, there remains the question why Dedecahedra have not to my knowledge been discovered in Italy, even if only taken there as spoils of war.

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