What’s that thing?
A Fidget Spinner, a toy that was a huge fad a while back.
The dodecahedra also have decoration all over them - inscribed circles and dots.
They look as centred to me.
Those look decorative to me. How much would they have cost?
They’re not particularly intricate in construction, nor highly decorated as Roman utilitarian objects go, and while bronze was costly, it wasn’t precious. They would not have been particularly expensive. It’s not like they’re some exotic material or a particularly involved process. The Romans used intricately cast bronze objects all the time. I mean, look at this key or any of these lamps.
Thanks. Heard of them; never saw one.
Then i wonder if they weren’t just a popular decorative knickknack. They might have represented the twelve something, but may have mostly just been an attractive object to put on the mantle.
Maybe the holes held a stick of incense.
Maybe, although Roman thymiateria (incense burners) are usually more of a candlestick shape. And seem to usually have a surface for catching ash.
The dodecahedra are small, as well, they don’t seem very practical for this use.
Also, just checking, everyone is aware that dodecahedra are commonly-occurring natural forms, right? Not the regular kind, but close enough for government work.
The incense holders I’ve seen are about the same size as those. They could just as well have held a single dried flower or a couple stalks of wheat or a feather. Or just sat by themselves as a knickknack. My house is full of knickknacks, so that seems like a plausible “use”.
I think we can agree, though, that these bronze objects are not naturally-occurring. And I don’t think that the Romans would have found it important to craft approximate replicas of the shape of a particular sort of crystal.
Look at the face that’s facing upwards in the picture (i.e., opposite of the table). If you draw a line between the centers of the two top small circles, it intersects the edge of the central circle, but if you draw a line between the top-left and bottom small circles, it doesn’t.
IIRC from a previous thread, @Mangetout made one of his own, and deemed them fairly difficult to make. Doubtless they’d become easier with practice, but just a knickknack seems unlikely to me.
I tried to make a lost wax cast replica in pewter - it didn’t go all that well (documented here), but my level of competence probably shouldn’t be taken as indicative of anything in particular; pretty sure I used the wrong casting matrix, for example.
It was however, the difficulty of that project that made me think this could be an object concieved as a test or demonstration of a craftsperson’s skill.
It’s very much not a flat face, and is in extreme low-angled view, I don’t think you can say anything about centredness from drawing any straight lines on it…
Mangetout hasn’t done a multi-year apprenticeship just in bronzework, wasn’t using the right kind of wax, used plaster rather than a ceramic slip, didn’t bake in a proper furnace to burn off the wax, and wasn’t casting with high-lead casting bronze. And he still made what I’d call a damn good replica, first time (until he then went too far in fixing the missing knobs)
I’ve never made a dodecahedron replica, but I have done lost wax bronze casting, and lots of casting with pewter. In my opinion, it’s not a particularly difficult object to make. The knobs would be the fiddliest bit, which is why
a) the examples I’ve seen with cast-on knobs often are not as stand-out as Mangetout’s copy
b) even the period Roman ones can have attached, not integral, knobs.
I mean, based on the examples of actual Roman bronze work I’ve linked to in this thread, I personally would not consider that simple geometric shape full of holes a particularly challenging thing to cast, if you already know how to cast, compared to a.bronze oil lamp or similar. All the actual hard work would be in the layout on the wax sheet.
Suffice to say I don’t agree with Mangetout’s opinion on this being a suitable test of skill. Not based on the kind of thing a bronzeworker would be expected to actually produce.
I wasn’t suggesting they were, just adding in some interesting trivia.
Even just “requires a basic level of competently knowing what one’s doing”, though, I think might price these things out of the knickknack level.
And I still think there has to be some reason for the holes to all be different sizes. You don’t make something that symmetric and precise, and then introduce an asymmetry like that, without some actual specific reason. Precise measurements of many specimens (along with, ideally, recording of which was on which face-- Like, is the largest hole always opposite the smallest hole, or the like?) would help to rule out a lot of hypotheses. My hunch is that the holes were the reason for the objects’ existence to begin with, that there was some practical task that called for a thing with holes of specific sizes, and the dodecahedron was just popular way of packaging them together.
For that matter, viruses and diatoms are also often Platonic shapes, including the pentagonal dodecahedron.
I only managed to find one set of measurements in a paper written in Flemish - they’re in my blog page I linked above, reproduced below; what surprised me a little is that the holes in opposing faces were generally quite closely similar; the pairs of opposite holes were:
- 10.6mm and 13.0 mm
- 13.8mm and 14.0 mm
- 25.2mm and 27.0 mm
- 20.3mm and 20.5mm
- 15.6mm and 17.8 mm
- 23.0mm and 26.0mm
With the exception of the 20.3 / 20.5 pair, I suppose it could be hypothesised that this setup was for quickly assessing the size some smallish spherical object - you have an object that needs to be between 23 and 26mm in diameter - if you can’t drop it through the 26mm hole at all, it’s too big - if it falls all the way through the other side, it’s too small; if it passes through the first hole and not the second, it’s just right.
Except that just seems rather an over-engineered solution for that sort of measuring task, and also, what even was that task? What sort of assorted small spheres did Romans need to measure? If they had muskets, it would make more sense…
Edit: I realise discs such as coins could also be sort of measured in the same way, although I think they wouldn’t be guaranteed to always fall through a hole so readily, and also, measuring the diameter of flat discs is even easier - requiring even less of an engineered solution.
I noticed many of them have two or three grooves around each hole. A couple possibilities: 1) The grooves serve a purpose when “using” the dodecahedron, or 2) they are an artifact from making the hole (i.e. the tool or whatever used to make the hole imprinted grooves), and do not serve a purpose when using the dodecahedron.
It seems that the circle/dot markings on each face are different; if the thing is a tool, they could be for easily identifying which size hole you are dealing with; the dots spaced around the hole could be references for marking intervals on some workpiece that was inserted in or through the hole.
Edit when I was searching for the sorts of small spherical items that Romans might have needed to measure, I found this interesting image of clay marbles - unfortunately its on Pinterest, where context goes to die. https://www.pinterest.co.uk/pin/359162139016679422/
I dunno, if it cost as much as a lamp, many people could afford one. And the randomness and complexity make it an appealing knickknack. And if it’s too cheap, it’s less interesting.
It certainly could have some practical use, but people like ornaments, and we aren’t talking about an impoverished society. And “knickknack” is the sort of thing that might remain regional.
Right, and if we had those measurements for all of them, then we could see whether they all have the same measurements, and if all of them have the same arrangement of sizes, and so on. If they do all have the same arrangement of sizes, then the arrangement of sizes is probably* important, but if they don’t, then it’s not. And you’d think that measuring the darned things would be the bare minimum level of study possible. It’s so frustrating that even that hasn’t been done-- Aren’t most of these owned by museums and similar institutions that are supposedly dedicated to study of their artifacts?
My guess there would be that the grooves correspond to the sizes of the larger holes: When you’re making a face, you use some sort of cookie-cutter-like template that makes grooves for all of the hole sizes, and then cut out the correct one from the grooves, so you only need one template instead of 12.
*But not necessarily. By comparison, almost all d20s have the same arrangement of numbers, even though that’s not the optimal arrangement, just because everyone apparently copies the arrangement from each other.
Though, perhaps on point, for whatever reason the same does not appear to be true of d12s.