TIL. In April 1974, in the middle of the night, a small group of conspirators secretly installed a large tensegrity icosahedron made from discarded telephone poles on the campus of Twente University in the Netherlands.
It’s still there. People call it Het Ding (“the thing”).
https://www.utwente.nl/en/alumni/inspiring-alumni/ut-canon/stories/het-ding/
@11011110 @robinhouston I was even more confused when I read the Dutch Wikipedia article in Firefox's translation, because it said
"Together they form a twenty-plane with fourteen equilateral and six equilateral triangles."
That seemed like a strange way of saying "twenty equilateral triangles"! But reverting to the Dutch, it's actually using two different words, fourteen "gelijkbenige" and six "gelijkzijdige". According to Wiktionary, the first of those means "isosceles", not "equilateral". Firefox's translation made a goof.
So this is apparently not a _regular_ icosahedron. Does that affect the question of whether it's chiral, perhaps?
@11011110 @robinhouston on reflection, I also don't believe those counts! If this sculpture has the form of Jessen's icosahedron, then surely it has _twelve_ isosceles triangles and _eight_ equilateral ones?
An easy mistake; clearly the equilateral triangles have something to do with a cube or its dual octahedron, and all you have to do is forget whether it's the faces or the vertices. I didn't spot it yesterday for that reason. But I got there in the end!
robinhouston
0xDE
Simon Tatham