We were interested to read Alex Chablo's query (Letters, AJ 3/10.8.00), where he asks about fitting interlocking hexagons onto a spherical surface.
This apparent contradict ion comes from the meaning of the word 'hexagon'. The technical definition is a planar shape with six sides. In this context, Grimshaw is correct in stating that methods are available for designing geodesic spheres tiled with irregular hexagons, such as the system used by Norman Foster and Buro Happold for the Globe Restaurant atop the Al Faisaliah tower in Riyadh.
However, in Weyl's book Symmetry, he must be referring to regular-hexagons (all six sides the same length), since it is indeed impossible to cover a sphere w ith regular-hexagons.
It should also be recognised that regular triangles (icosahedron) or a combination of hexagons and pentagons (truncated-icosahedron or buckyball) can also be used in various ways to form a spherical tiled surface.
Here at Buro Happold we write our own software routines (using C++ language) to create regular tiled and noded geometries falling on a variety of geometrical shapes to suit many and varied project requirements.
Ken Jones and Paul Shepherd, Buro Happold, Bath