... John Stephen Young . ... These results, described in Chapters 5-8, include high-quality images of Capella and Betelgeuse, and a large number of diameter measurements of Mira variables. ... Chapter 5 describes the procedures used when observing with COAST in the infrared, illustrated by observations of the binary star Capella. ... Chapter 7 presents the results of a programme to monitor the angular diameter of the Mira variable star chi Cygni. ... Astron. ... PhD thesis, University of Cambridge, 1995...