Acknowledgments

I am grateful to NRAO for observing time and to Daniel Puche for teaching me how to use the VLA. This work was made possible by financial support from an Australian Postgraduate Research Award, the Smithsonian Institution Predoctoral Fellowship program and the hospitality of the Australia Telescope National Facility. It has been improved through discussions with Frank Briggs, Lister Staveley-Smith and Wilfred Walsh.

© Copyright Astronomical Society of Australia 1997