J26 -- the Gyrobifastigium
TypeJohnson Solid
Panels 4 × Geomag triangle panel icon
4 × Geomag square panel icon
Rods 14 × Geomag rod icon
Spheres 8 × Geomag ball icon
Author PolyClare 19:42, 9 January 2008 (UTC)

This polyhedron was the 26th detailed in Johnson's seminal paper, consequently it's often notated J26, the 26th Johnson Solid. It may be formed by joining together two triangular prisms at square sides, ensuring that the axis of one prism is rotated (the "gyro" in the name) with respect to the other.

So... the "gyro" in the name is accounted for, the "bi" I assume refers to the two prisms, so what is "fastigium"? Aha!! A bit of googling reveals that fastigium = roof; peak; gable. Cool -- it's a pair of rotated roofs -- got it!

The Gyrobifastigium is notable because it is the only space-filling Johnson Solid. So I made a pair of 'em to play with fitting them together. Neat!

Other views Edit

Related links & references Edit

  • Norman W. Johnson, "Convex Solids with Regular Faces", Canadian Journal of Mathematics, 18, 1966, pages 169–200.