Australia and New Zealand boast an active community of scholars working in the field of history, philosophy and social studies of science. 'Australasian Studies in History and Philosophy of Science' aims to provide a distinctive publication outlet for their work. Each volume comprises a group of essays on a connected theme, edited by an Australian or a New Zealander with special expertise in that particular area. In each volume, a majority of the contributors is from Australia or New Zealand. CQntributions from elsewhere are by no means ruled out, however, and are indeed actively encouraged wherever appropriate to the balance of the volume in question. Earlier volumes in the series have been welcomed for significantly advancing the discussion of the topics they have dealt with. The present volume will I believe be greeted equally enthusiastically by readers in many parts of the world. R. W. Home General Editor Australasian Studies in History and Philosophy of Science Vll ACKNOWLEDGEMENTS The stimulus to assemble this collection of essays grew from a number of interesting seminars conducted during the academic years 1991-92, under the auspices of the Victorian Centre for the History and Philosophy of Science (which is centred at the Bundoora campus of La Trobe University in the outer suburbs of Melbourne). Some of the seminar presentations to the Victorian Centre for HPS and other articles awaiting pUblication have been made available as part of the Pre-print Series of the Victorian Centre.