MY THESIS

The work for my PhD thesis was carried out between 1975 and 1981 and the text was written during that period and the few years following, but was regrettably never submitted for the degree.  The chapters included here contain most of the original text and I am gradually trying to include more of the missing illustrations, equations and references.  Nevertheless it does contain some useful information and may prove of interest to some readers.  If there are particular aspects that you would like to have clarified I am easily contactable by email.