Having just discovered a fundamental flaw in my ideas about close packing of spheres, which for the uninitiated is how I've been looking at the aggregate proportions, I ran a search on "close packing spheres" and eventualy found this link. http://www.ac-noumea.nc/maths/amc/polyhedr/packing_.htm

The poem at the bottom of the page on http://www.pballew.net/soddy.html is some consolation, but I've now decided to lay down in a darkened room with a large G & T.

Cheers to all our readers
John