One of Archeology's Mysteries The Roman Dodecahedron

The Roman Dodecahedron: One of the Mysteries of Archeology

The Roman dodecahedron is a small, hollow object of a geometric shape with 12 flat faces, made of stone or bronze. In this way, each facet of which is pentagon, each corner point of the pentagons is decorated with a knob. Pentagons often contain circular holes in them. Researchers have been unable to understand the origin and function of this mysterious object for 300 years.

The first dodecahedron was discovered in the English countryside in Aston, Hertfordshire in 1739 by a local historian. Each object discovered later was different in structure and size.

The Roman dodecahedra is an object from the 2nd or 3rd centuries AD. Typically ranging in size from 4 cm to 11 cm, this object has been found in Switzerland, the Netherlands, France, Belgium, Great Britain, Germany, Luxembourg, Austria and Hungary. There are more than 100 examples of the work found. The specimen found in Geneva was made of silver. The dodecahedron, found in Idaean Cave, Crete, is made of rock crystal and has Greek characters instead of holes on its twelve faces.

What Was the Roman Dodecahedron Used For?

Two dodecahedra and an icosahedron on display in the Rheinisches Landesmuseum
Image Source: Two dodecahedra and an icosahedron on display in the Rheinisches Landesmuseum (Bonn, Germany) | Kleon3, CC BY-SA 4.0, via Wikimedia Commons

Roman dodecahedra, what does it do and how does it work? There are no documents or notes related to these mysterious objects, so the function of the dodecahedra is still not determined. However, many speculations and theories have been put forward. In one instance, the dodecahedra had a candle next to it, causing controversy over whether it was a candlestick.

A toy for throwing and catching on a stick, gauges for calibrating water pipes, surveying instruments, dice, devices for determining the optimal planting date for winter grain, scepter ornaments, geometric sculptures are theories for the function of the dodecahedra. Some of these theories are important.

A recent hypothesis for Dodecahedra’s purpose is that they were used as knitting tools to make gloves. The most accepted theory is that the Roman dodecahedron was used as a range measuring device on a battlefield. This might explain the different sized holes in the pentagrams. However, it has not been fully elucidated how the dodecahedron might be used for these purposes.

One interesting theory is the suggestion that dodecahedra is an astronomical measurement tool for determining the optimal planting date for winter grain. The dodecahedron was an astronomical measuring instrument that could measure the angle of sunlight, thereby determining exact dates for planting grain in the spring and autumn.

One theory claims that dodecahedra are religious relics that were once used as sacred tools for Caledonian and British druids. There is no archaeological evidence or written record to support this view.


Icosahedron similiar to the Roman Dodecahedron

Another discovery adds to the mystery about the function of these objects. The Roman icosahedron, a 20-sided polyhedron, was found by Benno Artmann. This discovery led to the question of whether there were many other geometric artifacts of different types, such as hexagons and octagons, that had not yet been found in the Roman Empire. Despite the many unanswered questions, Roman dodecahedrons were invaluable to their owners. Many of these objects were found among treasures along with coins and other valuables. Perhaps the true purpose of the Roman dodecahedra will never be known, but progress in archeology may reveal more clues to help unravel this mystery.

Ancient Roman civilization contains many secrets that even a lifetime of study cannot reveal to us. The object was not mentioned in Roman texts, and although the design of most objects was decorated with patterns, none contained numbers or letters to hint at their use.

15 thoughts on “The Roman Dodecahedron: One of the Mysteries of Archeology”

  1. Richard Allday

    *It appears that it could be used to measure coins, but old Roman coins in that time period were not very round. They were hammered on a die, not cast, so they weren’t a perfect circle. Weight and material constitution was more important to the value of an ancient coin, not a perfectly round shape (especially since the coins were debased of their silver so much during the 3rd century). In addition, some dods had triangular and oval holes.

    *Knitting tool?- interesting, but some dods are too small for this; also some holes are too small; finally, that type of ‘French’ knitting tube size is based on number of knobs(pins), not the opening/hole sizes.

    *range finder? – prob. not, as the dods found are all different sizes, with different opposing opening/hole size ratios & no numerical markings; also, some dod hole pairs would be measuring something so close to you, you wouldn’t need a range finder; also, there were other somewhat accurate range finders in use by the Romans. Finally, the device would have been found in a wider area.

    (Researched Opinion below)

    Could it be the original Swiss army multi-tool? Kinda…

    The enigmatic object many refer to as a Roman Dodecahedron (or ‘Dod’) is of Gallic/Gaul (including the Swiss Alps)/ Germania Superior & Inferior Origin (Northwest Gallic area). It was initially produced by Gallic-descendent blacksmiths (ordered by Negotiatores/Roman arms merchants in conjunction with Roman auxiliary army arms officers) as a ‘blueprint’/spec key, procurement & (in varied instances a) maintenance tool for polearm wood weapon shafts (mainly) for the Roman Auxiliary troops (of which polearm size/specs were varied)…for region-specific tribe/area troops. Some were also used to measure tool handle shaft diameters (including oval) -see Jublains Dod.

    Negotiatores/arms merchants, Auxiliary troop arms officers and mid-market woodworking (and other) merchants utilized the tool to efficiently measure/QC multiple weapon shafts in the business of procurement and maintenance. This would include the max shaft diameter at its expected max point along the shaft (in some instances and if applicable per auxiliary troop specs); the (exposed) shaft taper ‘just prior’ to where the shaft joints the metal head (if applicable per weapon), & the shaft taper that will be inside the metal weapon head socket. And (if needed) for maintenance – to replace damaged shafts in workshops located inside a fort or in a related Vicus, by removing the weapon heads (most auxiliary troop weapon heads are wider at the blade than the socket and are easily removable with the dod). Some were used as a maintenance jig to mark/actively taper shafts (see Corbridge Dod). Some dods with inscribed circles around the openings were used to measure/center & mark the end(s) of pre- or post-tapered shafts (to the desired final diameters at the head joint and end of the shaft).

    The Dod knobs (@ all the vertexes) served as a grip to remove the head from its shaft (usually wrap the weapon head with cloth prior), in one of multiple fashions including through a wedge opening, or used as a fulcrum with a varied lock bar, if twisting is needed…but inertia worked well with the weight of the dod (vs. the weapon head) & dropped on the weapon head for quick removal. The knobs also served as a tie-down when shaving or measuring shafts, or (in some cases) lathe tapering the end of multiple wood weapon shafts although most shafts would have been found to be shaved (vs. lathe turned) due to shaft thickness and length. The knobs also served to allow the shafts to efficiently pass through from the top to bottom of the dod, to ensure measurement caliber is acceptable – with a small tolerance (based on knob distance past the face openings).

    The sizes of different dods related to the length of the weapon shaft that resides inside the weapon head sockets.

    Contrary to published work comments, many dod openings DO show signs of chips/dents, scrapes and cuts (especially some of the larger opposing openings and the largest opposing openings – damage is not just from oxidation). This damage is due to the weapon heads being removed, and in some cases from using as a jig (see Corbridge dod), or ‘can-opener’ pry bar when ‘in-service’ weapon heads are broken-off at the head and wood needs to be removed in anticipation of a new shaft being inserted.

    All reviewed, published interior weapon socket shaft max/min diameters/tapers (in the ancient Gaul/Gallic/Britannia areas) are consistent with the size of the dod openings & opposing openings. Because of the wide variation of thrusting weapon shapes/sizes/shaft tapering in the published Dod find areas (as is understood through the archeological record), these dods would have logically been of different sizes and had/have different hole/opening sizes and opposing opening size ratios, for procurement/maintenance of these varying auxiliary troop’s weapons.

    The Dods began to be used during Roman fort expansions on the frontier regions of conquered Gaul in the Rhine/Danube regions (and beyond in Britannia) when weapon procurement was localized. Auxiliary troops (as opposed to the Legion troops) used many of their own traditional weapons which had different calibers, per tribe origin. There were many different tribes in the Gallic area that were not organized as one power, thus the differences in their weapons, & the dod opening sizes (and ratio of opposing opening sizes to each other), per dod.

    Shafts (and especially at the ends at the head joint) are the weakest part of the pole weapons and a relatively constant supply was necessary (either due to training or war, etc.). The Dods ensured the quality/specs of auxiliary troop-specific weapon shafts.

    Once inflation became out of control / coins being continually debased (near the late 3rd century+), the mass production of weapons was required & began, and the Dods were no longer needed as local/regional arms merchants were no longer supplying the (majority of the) weapons and there weren’t 30-40+ different sizes of polearm specs to be blueprinted for all the regions. In the coming years, the Roman empire declined & then dissolved in Western Europe.

    The ancient Swiss ‘Army’ (multi-tool) has come a long way since then…R.A.

    ©Jan-July 2023

Leave a Comment

Your email address will not be published. Required fields are marked *