Gas dynamical effects govern the physics of many objects in the Universe ranging in scale from the intergalactic to the circumstellar. This book gives an up-to-date survey of the latest findings and theories from acknowledged experts in this particular field of astrophysics. Cosmical Gas Dynamics includes papers on the following subjects: -- shock waves caused by supernova explosions -- jets and maser sources -- the effects of gravitational fields on interstellar gas -- flow patterns determining where star formation will occur -- the remnant of the nova Rho Ophiuchi which exploded on 26 January 1985

The following text forms the proceedings of a conference. It is supposed to contain what was actually reported and discussed, though it does this, one hopes, in a polished and organized way. A sense of actuality, a reporting quality, makes this book different from a collection of review papers as, for example, a book in the series on Stars and Stellar Systems. All Invited Reports have been included as the Reporters wrote them. The Editor's task has been restricted to improving the presentation, a process which in most cases involved only minor revisions. In a few Reports the Editor did some heavy rewriting; in those cases he checked with the Reporters. Obviously a different course had to be taken with respect to the Discussions. They were recorded on tape, transcribed verbatim and then passed back to the discussants. After the discussants returned their versions, the Editor rearranged and condensed the texts and made a considerable effort to provide references. (Unfortunately he was not able to locate all relevant Russian papers from 1968 and 1969. ) The Editor takes the responsibility for mistakes made in this process, which may have produced occasionally his own 'mix-master Universe'. Actually only a few discussion remarks were rejected, more often because of incomprehensibility, rather than because the remark was far from the subject of the Symposium, or was too long, or was too trivial. A few very long remarks have been condensed and put at the end of a Discussion.

The area of diffuse astrophysical media is enormous and ranges over circum stellar to extragalactic scales. The physical conditions can vary from cool dusty gases to collections of relativistic particles. Flows in such media are set up by en ergy and momentum injection from winds, jets and explosions. The study of these phenomena involves physics, chemistry and, inevitably, hydrodynamics. One of the most important aspects of this study is the ever increasing overlap between theory and observation. Indeed, it can be argued that the only way to really understand these complex flows which can never be duplicated under terrestrial conditions, is to encourage this overlap, and this was one major aim of this Conference. Because of the long theoretical and observational association of the Manchester Group with this general area, Manchester seemed an appropriate venue for this Con ference. But in fact this long association and the actual year of the Conference are connected. In 1951 Franz Kahn joined the Astronomy Department at Manchester University and immediately the study of diffuse media, particularly the hydrody namic aspects, commenced and has flourished ever since. Franz became Head of the Astronomy Department in 1981 following the retirement of Professor Z. Kopal, who founded the Department and was instrumental in attracting Franz to it. In 1993, Franz retired from this position and a most serendipidous coincidence was his election to the Royal Society announced shortly before the Conference.