Bumpy Dodecahedrons, what purpose did they serve?

[IWMP]

An odd feature of at least some of these things is that each face has a round hole in the middle and the holes on different faces are of different widths. In a regular dodecahedron, opposite faces are parallel. So one use for such a thing would be for measuring distances, as in surveying land.

If you look at something through two successive round holes, with the second one larger, there’s a particular eye distance from the first, smaller hole at which neither hole’s edge blocks the other. Then your field of view through both holes is a cone with a particular angle.

If you then look in that way at some distant object of known size, such that the object exactly fills your field of view, or stretches half-way or three-quarters across it or whatever, then you can work out how far away the thing is. Military binoculars today have little spaced lines etched in the lenses for doing this, but the principle could have worked in Roman times. Surveyors could have put out sticks of known length at property corners and then looked at them from another corner through parallel holes. They might have had sets of sticks in multiple standard lengths, to increase the chance that one stick would properly fit in the field of view.

And it could certainly have helped to have multiple pairs of viewing holes available, with different hole size ratios, so that you could find one pair whose view cone angle best fit one of your sticks at its particular distance. You’d get more accurate measurements that way, instead of having one standard angle and having to estimate whether your stick was 65% of the diameter of your field of view, or closer to 70%.

A dodecahedron with holes would give you six parallel hole pairs in one handy package, with the same fixed distance between all pairs. A cube would give you three pairs, an octahedron four pairs, an icosahedron ten pairs. Maybe six pairs was conveniently enough, ten pairs was overkill, and the dodecahedron became standardized. There could have been an element of ritual involved. If distances were important for legal ownership or taxation then they might be more accepted for being measured with a fancy dodecahedron instead of an equivalent but less impressive deal with boards and strings or whatever.

Sounds nice, and the idea has occurred to at least one other person besides me. I have no idea, though, whether Romans would actually have had any need for measuring distances that they didn’t just meet by pacing or stretching out ropes.

Some visual range finding method might be the only way of getting good measurements over uneven ground or across water. So maybe?

Would the hole pairs not have to be different sizes? I assumed it was a toy. My brain sings dreidel dreidel dreidel when I see it lol. Maybe some spiritual thing.

I like your explanation though. And I think, because they don't pop up everywhere, then they probably weren't a toy or ornament.

Edit, addition and spell correction.