Thanks David, Paul and Frank - with a couple of off-list replies i know a lot
more than i used to, for certain.  There does seem to be a LOT less research in
this area than one would expect, however, even given the reluctance of modern
governments and universities to sponsor or encourage "pure" research these days
(exept in particle physics, astonomy/astrophysics and "exobiology" , ie!!)

Feeling a bit more visible,
Ross.