I was saying what you could do if you wanted more standoff. Just pinching the corners would be sufficient to get the standoff from the boiler surface that your “test tube holder” hypothesis would need.
But they would also need to be knobs that weren’t to stand up to too much stress, given not all knobs are the integral kind.
I’m of the inclination that the knobs are decorative. A very particular, consistent, decoration, obviously, but not a functional one.
My pet theory is that one of these was initially made as some sort of token of some cultic concept (or a non-utilitarian secular one like a trophy or similar), and the others are copies of the same. Many are copies by bronzeworkers who were shown either that original or a good copy, and some are copies made from a description.
Surely the easiest way is to try for as much of this in the casting, but then just fine-tune it with some filing/sanding after, in the clean-up phase? Even build extra volume in the knobs for that purpose. That kind of fine adjusting by filing is the kind of thing I see Chris from Clickspring do all the time.
The knobs could have had some other decoration mounted on them. Nothing very large, so not putting much stress on them.
And how many are actually complete? I know some of them are broken. One I saw (found in Belgium, IIRC) was only a single corner with its knob. Very partial, but still recognizable as part of a dodecahedron.
Possibly, although I feel like Chris would get it sufficiently right on the first pass that such adjustments would only need to be removing tiny amounts of material.
The key issue is that each knob is part of the border of three different faces - if you need to take too much off for one, it might affect the set of the other two adjoining faces, or make the knobs seem lopsided or non-knobby (as might also be true if you provide additional material in advance to accommodate later adjustment)
Obviously it’s a fairly solvable problem because the quality of some of the extant dodecahedra is quite nice and neat and regular.
I think the majority of adjustment and fit would probably be done in the wax stage, because it’s just a lot easier - building up a protruding part can be done by just painting on or dipping into melted wax; and the opposite adjustment can be done by scraping or carefully warming a small area.
The various casting processes can introduce distortion that was not present in the wax form; clay tends to shrink as it dries; bronze may warp as it freezes and cools - some of the ‘repair’ examples that are seen on extant dodecahedra may have happened right after casting - if for example one knob was clearly out of whack, the simplest fix might have been to cut or snap it off and solder a new one on in the right alignment.
The site listed below presents an interesting theory. The dodecahedrons can be used to keep track of the angle of the sun in order to know the optimum time to plant winter wheat, and dodecahedrons were mostly found in areas where winter wheat was planted. Variations in the dodecahedrons were maybe due to adjustments necessary for different latitudes.
This site has a free PDF download link for R. Nouwen’s 1993 book The Gallo-Roman pentagon-dodecahedron: myth and enigma. It appears to have a great deal of data on dodecahedra, including maybe an inventory of all dodecahedra known in 1993. Could someone teach me to read Dutch real quick?
Saegewerk also has a list of dodecahedra, but it is less comprehensive, I think.
But if it was just being used to track the angle of the sun, why don’t we see lots of ceramic versions? Clay is a lot cheaper than bronze, and would work fine for that.
I daresay a clay version of a sun calendar might be just loads simpler to make than the Roman dodecahedra.
Make a bowl with deep sides and allow it to dry leather-hard. Place on a level surface. Pierce a hole in one side and place that to face the sun. Observe where the dot of light falls on the inside, opposite the hole. Mark this spot. Dry and fire the bowl.
I think if you are trying to identify a particular date of the year, you’d want something that finds the sun’s angle with good precision. Like a tiny hole, or a gnomon. Those huge holes in the dodecahedra don’t seem very well suited to that task. And this theory would imply that the knobs are formed to millimeter precision to place the dodecahedron at the right angle, which to my eye doesn’t seem to be the case. And of course, the Romans did make sundials, which look pretty much like you expect a sundial to look. Nothing like the dodecahedra.
I’m not convinced this is the reason these things were made but if they are used as range finders the knobs would provide a way to hang one from a bracket or tripod, and a plumb bob could be hung from the bottom to locate the device over a ground marker. If they were used in this manner each one could be matched to a pole with a marker at a specific height so the varying hole sizes in different dodecahedra don’t matter. A similar technique is used for golf range finders based on the height of the flags in the holes.
Is it possible the area of Europe where these were found was undergoing surveying of borders and property lines for the first time? Possibly the land in Rome and other regions had property lines established and well marked long before these devices appeared, or they just used other surveying techniques.
The problem is leveling the device and establishing the vertical angles unless it was used on relatively level land or they just didn’t care in the way they surveyed. I don’t think this is a convincing explanation though. And once again doesn’t explain why ceramic or even wooden versions have been found. There’s no great reason they have to be made as a single piece either. Much simpler transit devices can be made.
No matter what it is for, if it is being hauled around and used in the field, a ceramic doodad might be more fragile than a bronze doodad, so they opted make them sturdy?
Or… the ceramic ones, being nonconductive, didn’t work as well for signaling the aliens when the Roman signal corps hooked them up to their Baghdad batteries. (Hmm… mental note - knobs could be wiring attachment points…)
Roman surveying tools and methods are very well known and understood. Particularly the Romans knew about the adverse effects of using short baselines and small instruments in producing big measuring areas. The only surveying use I can see for it is for a surveyor to hurl at a chainman to get him to quit day-dreaming.
Or a Henge. “When the tip of the shadow of that big rock over there falls at the foot of this other rock here, plant your barley” I suppose that is just a gnomon.
The rangefinder idea seems at first that it might have more legs, but some of the holes are pretty big - if you try to sight through it so that a distant object fills the hole opposite, the object has to be huge, or not all that distant.
Unless you have to hold the dodecahedron at some specific distance from your eye, in which case it’s only part of the necessary paraphernalia to do the job, and in that case, why is it a discrete object at all?
That’s another question to add to the list of questions:
is it the juxtaposition/ratio of paired holes in opposite faces that matters, or just that they are not all the same?
In some examples, there are several faces that have very similar sized holes, so it seems like there might not be a need for them all to be unique, which does tend to suggest that it’s the ratio of opposite holes that matters (I suppose then only if the thing has an actual function beyond looking like it does).
IMHO after seeing the artifacts and other Roman items, I bet that these objects are more related to fortune telling or gambling. Or for both reasons.
One curious bit for me is how many dodecahedrons have engravings or designs that are round and concentric on their sides, looking a lot as the round circles around the dots on the sides of ancient roman dice.
One interesting bit for me, that applies to one reason the Romans did not bother to have the sides of the dodecahedrons to be regular, they may had their reasons. Both for the ones gambling and the ones making augurs.
‘Musical instrument’ is in the list upthread; maybe they could be wind-chimes? Would explain the use of metal, the knobs possibly, and the decorative, varying appearance. Then the whimsical blacksmith making his fortune from them died, and the purpose of the dodecahedrons forgotten.
Maybe not the instrument itself but a tool to make musical instruments. Pipe organs and their predecessors were being made in the time period estimated for these objects. These may have been gauges for making organ pipes or some other type of musical instrument. The diameters of the holes would have to consistently have a regular pattern of hole diameters which could be applied to a musical instrument.
The shape appears to matter more than the finish; consider these two examples:
Looking at these two, it’s tempting to think of some game played around a table where players had to try to toss a small ball or a pebble or other small object into the hole in the top; if they succeed, the object is turned so the next smallest hole is facing up, and play continues until they fail.
But I don’t think it can be that, because for one, it doesn’t sound fun for the other players to judge - trying to be sure that the person playing actually got a small, fast-moving object through the top hole wouldn’t necessarily be easy, especially when it’s not broad daylight. Also, that sort of game just wouldn’t work with the smaller versions like this:
And also, if you want a pub game where you toss things into a container, cups exist.
(Hmm… mental note - knobs could be wiring attachment points…)
that these objects are more related to fortune telling or gambling. Or for both reasons.
