In the last few years great improvements in the study of stellar jets and bipolar outflows have been achieved, both observationally and theoretically. High resolution observations at various frequencies (radio, IR, optical and X-ray) of these features in different types of objects have shown a large variety of morphologies at all scales often revealing contrasting symmetries which do not allow straightforward kinematic interpretations valid for all cases. In particular, at present, it seems very difficult to give a statistical definition of what the "standard properties" of jets and bipolar outflows are. On the theoretical side, the identification of physical processes capable of producing the observed rich morphological variety of jets and bipolar outflows and supporting them over long lifetimes is still controversial. Furthermore several models are actively discussed in an attempt of reaching a complete understanding of the phenomenon. The workshop provided an unique opportunity for both observers and theoreticians to gather together and produce an updated and exhaustive picture of the field. In addition the meeting has been enriched by the presentation of some works on jets in external galaxies. This topic was focused on what people working on stellar jets could learn from colleagues working on extragalactic jets and vice versa. Invited papers were prepared with the aim of giving the state of the art about scientific subjects; contributed papers and some selected poster papers presented, on the contrary, very recent results in the various fields.

A wealth of new experimental and theoretical results has been obtained in solar physics since the first edition of this textbook appeared in 1989. Thus all nine chapters have been thoroughly revised, and about 100 pages and many new illustrations have been added to the text. The additions include element diffusion in the solar interior, the recent neutrino experiments, methods of image restoration, observational devices used for spectroscopy and polarimetry, and new developments in helioseismology and numerical simulation. The book takes particular advantage of the results of several recent space missions, which lead to substantial progress in our understanding of the Sun, from the deep interior to the corona and solar wind.

Prof. Leon Mestel has been an inspiration to many to study the role of magnetism in the Cosmos. To mark the occasion of his retin'ment from the University of Sussex after 43 years in astrophysics, several of his friends and former students decided to hold an advanced research workshop in his honour. NATO agreed to finance this venture which was held at the Institute of Astronomy at Cambridge. The scientific organizing committee was J. Landstreet, D. Lynden-Bell, F. Pacini, M.A. Rud0rman and N.O. Weiss and most leading experts on Cosmical magnetism agreed to come. We are particularly grateful to Lyman Spitzer who, ably helped by his wife Doreen, !!;ave the after dinner addre~s on how the goddess Astrophysica had foreseen Leon's achievements in classical Greek times. Not without regret we decided to maintain the homog0neity of the material and therefore could not cover Leon Mestel's major achievements in non-magnetic astronomy. His work on the cooling of white dwarfs, his understanding that degenerate hydrogen was a nuclear explosive since its pressure was almost independent of temperature and hence, his picture of supernovae, which is now more commonly applied to novae, his seminal understanding of the 'law' of galactic rotation and his work on the non-linear development of t hp anisotropies generated in gravitational collapse.

The nature of time has long puzzled physicists and philosophers. Time potentially has very fundamental yet unknown properties. In 1993 a new model of multi-dimensional time was found to relate closely to properties of the cosmological redshift. An international conference was subsequently convened in April 1996 to examine past, current and new concepts of time as they relate to physics and cosmology. These proceedings incorporate 34 reviews and contributed papers from the conference. The major reviews include observational properties of the redshift, alternative cosmologies, critical problems in cosmology, alternative viewpoints and problems in gravitation theory and particle physics, and new approaches to mathematical models of time. Professionals and students with an interest in cosmology and the structure of the universe will find that this book raises critical problems and explores challenging alternatives to classical viewpoints.

From the beginning of Space Astronomy, the Extreme Ultraviolet band of the spectrum (roughly defined as the decade in energy from 90-900 A) was deemed to be the unobservable ultraviolet'. Pioneering results from an EUV telescope on the Apollo-Soyuz Mission in 1975 forcibly demonstrated that this view was incorrect; but it required the all-sky surveys of the English Wide-Field Camera and the Extreme Ultraviolet Explorer to demonstrate the broad potential of this field. Over 700 EUV sources have now been detected. Over 150 researchers from 16 countries gathered to share results in this new field at the International Astronomical Union Colloquium No. 152. Papers were presented on a wide variety of topics including cool star coronae, white dwarf atmospheres and evolution, neutron stars, the Io torus, cataclysmic variable stars, active galactic nuclei, the interstellar medium, winds and atmospheres of early type stars, and EUV plasma diagnostics. Selected manuscripts from this meeting are provided in these Conference Proceedings."

The last decade has been witness to many exciting and rapid developments in the fields of Nuclear Physics and Intermediate Energy Physics, the interface between Nuclear and Elementary Particle Physics. These developments involved to a large extent the sub nucleonic degrees of freedom in nuclei. In deep inelastic lepton scattering from nuclei, for example, it was observed that the quark structure of the nucleon is influenced by the nuclear medium. Also, the spin-dependent structure function of the nucleon was found to differ from sum rules based on SU(3) symmetry, a discrepancy referred to as the "spin crisis". In pion electroproduction at threshold and in the production of pions and other mesons in heavy ion collisions at intermediate energies interesting experimental results have been obtained, which triggered lively theoretical discussions. Furthermore, the search for the quark-gluon plasma phase of hadronic matter, a phase that is supposed to have existed in the first few seconds of the Big Bang, has been intensified. Not only were these developments accompanied by technical developments, such as the building of new experimental facilities, but also extensive theoretical efforts have been directed towards understanding these phenomena. These concerted efforts will hopefully lead to an understanding of the transition from the non-perturbative QCD regime to the perturbative one, in which the quark structure of nucleons is better understood. All of the aforementioned developments occur at a high pace, making it difficult to incorporate them into the courses offered to advanced students.

Data archiving has, for many years, been the most disregarded aspect of all data systems. The increase in numbers of telescopes, both groundbased and space-borne, and the increase in efficiency of detectors have generated overwhelming amounts of data. Much of these data were and are not used on short timescales and (should) have been archived, where they can be used later and/or by others. Archiving is essential. Objects can change in the course of time. New technological or scientific developments might require observing objects again. The cost-benefit ratio will become more and more important when considering the allocation of telescope time. The retrieval of old' data can then be crucial. At present there are a number of data collections and data retrieval systems. This book includes a series of clear and up-to-date descriptions of many important available data systems. For professional astronomers, librarians and computer engineers.

Contemporary research in atomic and molecular physics concerns itself with studies of interactions of electron, positron, photons, and ions with atoms, molecules, and clusters; interactions of intense ultrashort laser interaction with atoms, molecules, and solids; laser assisted atomic collisions, optical, and magnetic traps of neutral atoms to produce ultracold and dense samples; high resolution atomic spectroscopy and experiments by using synchrotron radiation sources and ion storage rings. In recent years, important advances have been made in the experimental as well as theoretical understanding of atomic and molecular physics. The advances in atomic and molecu lar physics have helped us to understand many other fields, like astrophyics, atmo spheric physics, environmental science, laser physics, surface physics, computational physics, photonics, and electronics. XII National Conference on Atomic and Molecular Physics was held at the Physics Department, M. 1. S. University, Udaipur from 29th Dec. 1998 to 2ndJan. 1999 under the auspices of the Indian Society of Atomic and Molecular Physics. This volume is an outcome of the contributions from the invited speakers at the conference. The volume contains 24 articles contributed by the distinguished scientists in the field. The contrib utors have covered a wide range of topics in the field in which current research is being done. This also reflects the trend of research in this field in Indian universities and research institutes. We are grateful to the national programme committee, national, and local organiz ing committees, and members of the Physics Department and Computer Centre, M. 1.

More than two centuries have elapsed since the story of the interacting binary stars began with the rediscovery of the variability of Algol by John Goodricke and the interpretation he proposed for explaining the regular periodic brightness variations which he found. Over this long span of time our knowledge about these systems has been growing, and we have now reached a fairly good understanding of the structure and behavior of this interesting group of objects. This book contains a timely summary of our present knowledge of interacting binary stars. The chapters have been written by distinguished scientists who have done relevant research in the field of interacting binary stars.

The ability of storing, managing, and giving access to the huge quantity of data collected by astronomical observatories is one of the major challenges of modern astronomy. At the same time, the growing complexity of data systems implies a change of concepts: the scientist has to manipulate data as well as information. Recent developments of the WorldWideWeb' bring interesting answers to these problems. The book presents a wide selection of databases, archives, data centers, and information systems. Clear and up-to-date descriptions are included, together with their scientific context and motivations. Audience: This volume provides an essential tool for astronomers, librarians, data specialists and computer engineers.

This textbook provides an introduction to the fundamentals of space physics and astrophysics and covers the recent progress in various aspects of these fields. In the introductory Chapter 1, a brief historical account of space research is given, followed by short reviews of the space vehicles used and some aspects of the early years of space research. In Chapter 2, the reader is introduced to the discoveries of the radiation belts and the magnetosphere of the Earth. Chapter 3 begins with the phenomena of the quiet Sun, followed by processes in the active Sun (solar flares, radio bursts and X-ray, gamma-ray and neutron emissions). In Chapters 4 and 5, attention is paid to the physical features and properties of large bodies and aggregates in the matter of the solar system, emphasising discoveries obtained from spacecraft. In Chapter 6 solar energetic particles are presented, bringing out their dual role - as a sample of accelerated matter from the Sun and as a sensitive probe of the interplanetary fields in the heliosphere. Chapter 7 presents a discussion on galactic cosmic rays, explaining the basic features and main findings. Highlights of ultra-high-energy cosmic rays and possible origins are included. Chapter 8 presents exciting results of extreme UV, infra-red, X-rays and gamma-rays from space. These are followed by outlines of the new vistas of cosmological problems as revealed by the cosmic background measurements of X-rays, gamma-rays and microwaves. In Chapter 9, the reader is introduced to the physical and dynamical properties of the interstellar medium. This chapter concludes with the astrophysical aspects of the search for the origin of life. In the concluding Chapter 10 some general trends and future directions are briefly presented. The level of presentation is aimed at senior undergraduate students who are familiar with introductory physics. Graduate students will find more advanced topics discussed through their underlying features. Each chapter is followed by a number of problems; solving these will enable students to obtain a good grasp of the topics.

This volume consists of invited lectures and seminars presented at the NATO Advanced Study Institute "The Infrared and Submillimetre Sky after COBE", which was held at the Centre de Physique Theorique of Les Houches (France) in March 1991. The school has been planned by a Scientific Organizing Committee. It was organized with the aim of providing students and young researchers with an up-to-date account of the Cosmic Microwave Background, the Cosmic Infrared Background (if any), and the infrared emission of the Galaxy, after the early results from COBE (Cosmic Background Explo- rer). It was attended by about sixty researchers from many countries. The lectures and seminars represent a complete coverage of our present knowledge and understanding of: the Early Universe, Large-Scale Structure, Dust in Galaxies, Infrared to Submillimetre Backgrounds, CMB Anisotropies, complementary observations and instrumentation problems, etc. Most of these lectures are reproduced in this volume. Unfortunately, a few lecturers have chosen not to submit their manuscript. I would like to express my gratitude to the Scientific Affairs Division of NATO (North Atlantic Treaty Organization) and to the Theoretical Physics and Astrophysics Sections of the CNRS (Centre National de la Re- cherche Scientifique) for their generous support. Further help was obtain- ed from the DRET (Direction des Recherches, Etudes et Techniques), the CNES (Centre National d'Etudes Spatiales) and the IN2P3 (Institut Natio- nal de Physique Nuc1eaire et de Physique des Particules), which I hereby gratefully acknowledge.

Tracing unexplored connections between nineteenth-century astronomy and literature, The Starry Sky Within offers a new understanding of literary point of view as essentially multiple, mobile, and comparative. Nineteenth-century astronomy revealed a cosmos of celestial systems in constant motion. Stars, comets, planets, and moons coursed through space in complex and changing relation. As the skies were in motion, so too was the human subject. Astronomers showed that human beings never perceive the world from a stable position. The mobility of our bodies in space and the very structure of stereoscopic vision mean that point of view is neither singular nor stable. We always see the world as an amalgam of fractured perspectives. In this innovative study, Henchman shows that the reconceptualization of the skies gave poets and novelists new spaces in which to indulge their longing to escape the limitations of individual perspective. She links astronomy and optics to the form of the multiplot novel, with its many centers of consciousness, complex systems of relation, and criss-crossing points of view. Accounts of a world and a subject both in relative motion shaped the form of grand-scale narratives such as Tess of the D'Urbervilles, Bleak House, and Daniel Deronda. De Quincey, Tennyson, and Eliot befriended leading astronomers and visited observatories, while Hardy learned about astronomy from the vast popular literature of the day. These writers use cosmic distances to dislodge their readers from the earth, setting human perception against views from high above and then telescoping back to earth again. What results is a new perception of the mobility of point of view in both literature and science.

ROSAT Observations G. HASINGER Max-Planck-Institut flir extraterrestrische Physik, D-85740 Garching, Germany Abstract. This review describes the most recent advances in the study of the extragalactic soft X-ray background and what we can learn about its constituents. The deepest pointed observations with the ROSAT PSPC are discussed. The logN-logS relation is presented, which reaches to the faintest X-ray fluxes and to the highest AGN surface densities ever achieved. The N(>S) relation shows a 2 density in excess of 400 deg- at the faintest fluxes and a flattening below the Einstein Deep Survey limit. About 60% of the extragalactic background has been resolved in the deepest field. Detailed source spectra and first optical and radio identifications will be discussed. The results are put into perspective of the higher energy X -ray background. Key words: X-rays, background radiations, active galactic nuclei. 1. Introduction The extragalactic X-ray background (XRB), discovered about 30 years ago, has been studied extensively with many X-ray experiments, in particular with the satel lites HEAO I and II (see ego Boldt 1987) and with ROSAT (e. g. Hasinger et aI. , 1993). Figure 1 shows a compilation of some of the most recent spectral measure ments for the X-ray background. Over the energy range from 3 to about 100 keY its spectrum can be well approximated by an optically thin thermal bremsstrahlung model with kT ~ 40 keY, while at lower X-ray energies a steepening into a new component has been observed observed (e. g.

After a year's successful operation, the European DENIS project is now a scientific reality and its close cousin 2MASS (USA) is about to come into operation. The observational and data reduction processes of both DENIS and 2MASS are fully described in this volume. Already the impact of DENIS is making itself felt in the astronomical community in areas of research as diverse as cosmology, the evolution of galaxies, the interstellar medium, the search for brown dwarfs, and stellar structure and evolution. The first routine results from DENIS and the preliminary results from the 2MASS prototype camera are discussed and compared with other surveys across the wavelength spectrum, both space- and ground-based, including the Digitized Sky Survey, ISO and ROSAT.

An invaluable reference for any student, scientist or administrator, using small telescopes for research. An essential collection of data and opinions for those charged with setting scientific and funding priorities.

This three-volume set, The Future of Small Telescopes in the New Millennium details the essential roles that small telescopes should play in 21st century science and how their future productivity can be maximized. Over 70 experts from all corners of the international astronomical community have created a definitive reference on the present and future of "big science with small telescopes."

Despite highly publicized closures of telescopes smaller than 4-m in aperture at national facilities and their omission from national science priority studies, the oft-lamented demise of the small telescope has been greatly exaggerated. In fact, the future of these workhorses of astronomy will be brighter than ever if creative steps are taken now. This three-volume set defines essential roles that small telescopes should play in 21st century science and the ways in which a productive future for them can be realized. A wide cross-section of the astronomical community has contributed to a definitive assessment of the present and a vision for the future.

Volume 1: Perceptions, Productivities and Policies: - Beginning with a summary of recent national scientific priority-setting efforts, Volume 1 examines the public's and the astronomical communities' own perceptions and misconceptions of small telescope productivity. These shape the future scientific research that will be done with telescopes smaller than 4-m in aperture and the number of astronomers that will have access to them.

Volume 2: The Telescopes We Use: - Small cost-effective optical-, radio- and space-based facilities face similar problems in scientific prioritization and funding. Volume 2 highlights how current small facilities are evolving to meet the scientific priorities and economical realities of the 21st century through standardization of instrumentation, use of off-the-shelf technology, specialization, optical improvements, new modes of scheduling, automation, and internet access.

Volume 3: Science in the Shadow of Giants: - What first-rank science can small telescopes contribute in the coming era of 30-m class giant telescopes? Volume 3 explores a broad selection of scientific initiatives, from planetary astronomy to cosmology, that are ideally suited for small telescopes.

The Future of Small Telescopes in the New Millennium is a fundamental resource for those looking to undertake new projects with small telescopes, for those that are responsible for their operation, and for those called upon to help set scientific priorities for the coming decade. It will be useful for the practicing researcher, mountain facility manager, science policy maker, and beginning graduate student.

Telescopes and Techniques has proved itself in its first edition, having become probably one of the most widely used astronomy texts, both for numerate amateur astronomers and for astronomy and astrophysics undergraduates. The first and second editions of the book were widely used as set texts for introductory practical astronomy courses in many universities.
This book guides the reader through the mathematics, physics and practical techniques needed to use telescopes (from small amateur models to the larger instruments installed in many colleges) and to observe objects in the sky. Mathematics to around Advanced Placement standard (US) or A level (UK) is assumed, although High School Diploma (US) or GCSE-level (UK) mathematics plus some basic trigonometry will suffice most of the time. Most of the physics and engineering involved is described fully and requires no prior knowledge or experience.
This is a how to book that provides the knowledge and background required to understand how and why telescopes work. Equipped with the techniques discussed in this book, the observer will be able to operate with confidence his or her telescope and to optimize its performance for a particular purpose. In principle the observer could calculate his or her own predictions of planetary positions (ephemerides), but more realistically the observer will be able to understand the published data lists properly instead of just treating them as recipes. When the observer has obtained measurements, he/she will be able to analyze them in a scientific manner and to understand the significance and meaning of the results.
Telescopes and Techniques, 3rd Edition fills a niche at the start of an undergraduate astronomer s university studies, as shown by it having been widely adopted as a set textbook. This third edition is now needed to update its material with the many new observing developments and study areas that have come into prominence since it was published. The book concentrates on the knowledge needed to understand how small(ish) optical telescopes function, their main designs and how to set them up, plus introducing the reader to the many ways in which objects in the sky change their positions and how they may be observed. Both visual and electronic imaging techniques are covered, together with an introduction to how data (measurements) should be processed and analyzed. A simple introduction to radio telescopes is also included. Brief coverage of the most advanced topics of photometry and spectroscopy are included, but mainly to enable the reader to see some of the developments possible from the basic observing techniques covered in the main parts of the book."

We are well aware of how dust influences our observations of distant stars and how easily dust may mislead us with regard to the way in which stars are distributed within the Galaxy, but how does dust affect our view of other galaxies? This is the question that was posed to those who attended this meeting. By its very nature dust is illusive: as dust obscures by both scattering and absorption, it can effectively disguise its very own existence. It was not until the mid-1930's that astronomers generally agreed that dust did redden and dim stars in our own Galaxy, and it was not until the late 1950's that astronomers began to seriously inquire of its effects in other galaxies To the best of our knowledge, this is the first international meeting to have been held devoted solely towards understanding the observational effects of dust in other galaxies. Because of this we have been fortunate in attracting many of the major workers in this field, both observers and theorists. Among these pages the reader will find a wide range of opinion about how much dust there is in the disks of galaxies, where that dust is, and how to model the effects of dust. We tried to structure this meeting so that there was a ready and easy exchange between the speaker and the audience, and so that there was a large amount of time for discussion.

The study of white dwarfs has been steadily growing during the last years and now is a mature field extending its influence over many others. Since white dwarfs are long lived objects, they can be used to obtain information about the history of the Galaxy. The simplicity of their structures enables them to act as precise particle physics laboratories and the extreme con ditions reached at their surfaces allow us to test the equation of state and to study the behavior of matter under conditions impossible to be reached in terrestrial laboratories. Nevertheless, white dwarfs are still challenging astrophysicists. Many questions, ranging from the determination of funda mental parameters to the evolution of their outer layers, are still waiting for a satisfactory answer. The European Workshop series on White Dwarfs started in 1974 as a con sequence of the effort and enthusiasm of Professor Volker Weidemann. The existing proceedings of these meetings, together with those corresponding to the lAU Colloquia held in Rochester (1979) and in Hanover (1988), provide a unique opportunity to follow the development of this field. We hope that the present volume will provide a representative snapshot of the state of the art in 1996. In this sense we are very indebted to all the participants that have sent their contributions according to the instructions (this clearly excludes everybody beyond three sigmas from the standards).

One service mathematics has rmdcred the 'Et moi, .*.* si j'avait su comment en rcvenir. human race. It has put common sense back je n'y semis point aile.' whc:rc it belongs, on the topmost shcIl next Jules Verne to the dusty callister labc:1lcd 'discarded non- sense'. The series is divergent; thererore we may be Eric T. Bell able to do something with iL O. Hcavisidc Mathematics is a tool for thought. A highly necessary tool in a world where both feedback and non- linearities abound. Similarly, all kinds of parts of mathematics serve as tools for other parts and for other sciences. Applying a simple rewriting rule to the quote on the right above one finds such statements as: 'One service topology has rendered mathematical physics ...'; 'One service logic has rendered com- puter science ...'; 'One service category theory has rendered mathematics ...'. All arguably true. And alI statements obtainable this way form part of the raison d'etre of this series.

The Olympia conference Frontiers of Fundamental Physics was a gathering of about hundred scientists who carryon their research in conceptually important areas of physical science (they do "fundamental physics"). Most of them were physicists, but also historians and philosophers of science were well represented. An important fraction of the participants could be considered "heretical" because they disagreed with the validity of one or several fundamental assumptions of modern physics. Common to all participants was an excellent scientific level coupled with a remarkable intellectual honesty: we are proud to present to the readers this certainly unique book. Alternative ways of considering fundamental matters should of course be vitally important for the progress of science, unless one wanted to admit that physics at the end of the XXth century has already obtained the final truth, a very unlikely possibility even if one accepted the doubtful idea of the existence of a "final" truth. The merits of the Olympia conference should therefore not be judged a priori in a positive or in a negative way depending on one's refusal or acceptance, respectively, but considered after reading the actual of basic principles of contemporary science, new proposals and evidences there presented. They seem very important to us.

The NATO Advanced Study Institute "Cosmological Aspects of X-Ray Clus ters of Galaxies" took place in Vel en, Westphalia, Germany, from June 6 to June 18, 1993. It addressed the fruitful union of two topics, cosmology and X-ray clus ters, both of which carry substantial scientific weight at the beginning of the last decenium of the last century in the second millenium of our era. The so far largest X-ray "All-Sky Survey," observed by the ROSAT X-ray satel lite, and ROSAT's deep pointed observations, have considerably enlarged the base of X-ray astronomy, particularly concerning extragalactic sources. Cosmology has gained significant impetus from the large optical direct and spectroscopic surveys, based on high quality 2-dimensional receivers at large telescopes and powerful scan ning devices, harvesting the full information 1 content from the older technique of employing photographic plates. Radioastronomy and IR-astronomy with IRAS, as well as r-astronomy with GRO, continue and strengthen the role of extragalactic research. The rapidly growing computer power in data reduction and data storage facilities support the evolution towards large-number statistics. A most significant push was given to early cosmology by the needs of physics in trying to unravel the nature of forces which govern our material world. The topic of the ASI was chosen because it opens new vistas on this for ever new problem: the universe. Clusters of galaxies probe large-scale matter distributions and the structure of space-time."

In this book are reported the main results presented at the "Fourth International Workshop on Data Analysis in Astronomy," held at the Ettore Majorana Center for Scientific Culture, Erice, Sicily, Italy, on April 12-19, 1991. The Workshop was preceded by three workshops on the same subject held in Erice in 1984, 1986 and 1988. The frrst workshop (Erice 1984) was dominated by presentations of "Systems for Data Analysis"; the main systems proposed were MIDAS, AlPS, RIAIP, and SAIA. Methodologies and image analysis topics were also presented with the emphasis on cluster analysis, multivariate analysis, bootstrap methods, time analysis, periodicity, 2D photometry, spectrometry, and data compression. A general presentation on "Parallel Processing" was made which encompassed new architectures, data structures and languages. The second workshop (Erice 1986) reviewed the "Data Handling Systems" planned for large major satellites and ground experiments (VLA, HST, ROSAT, COMPASS-COMPTEL). Data analysis methods applied to physical interpretation were mainly considered (cluster photometry, astronomical optical data compression, cluster analysis for pulsar light curves, coded aperture imaging). New parallel and vectorial machines were presented (cellular machines, PAPIA-machine, MPP-machine, vector computers in astronomy). Contributions in the field of artificial intelligence and planned applications to astronomy were also considered (expert systems, artificial intelligence in computer vision).

Accretion disks in astrophysics represent the characteristic flow by which compact bodies accrete mass from their environment. Their intrinsically high luminosity, and recent progress in observational accessibility at all wavelength bands, have led to rapidly growing awareness of their importance and made them the object of intense research on widely different scales, ranging from binary stars to young stellar objects and active galactic nuclei. This book contains the proceedings of the NATO Advanced Workshop on `Theory of Accretion Disks 2' for which some of the most active researchers in the different fields came together at the Max-Planck-Institut for Astrophysics in Garching in March, 1993. Its reviews and contributions give an up-to-date account of the present status of our understanding and provide a stimulating challenge in discussions of open questions in a rapidly developing field.

A physicist and an inventor, Jules Janssen (1824-1907) devoted his life to astronomical research. He spent many years traveling around the world to observe total Solar eclipses, demonstrating that a new era of science had just come thanks to the use of both spectroscopy and photography, and persuading the French Government of the necessity of founding a new observatory near Paris. He became its director in 1875. There, at Meudon, he began routine photographic recordings of the Sun surface and had a big refractor and a big reflector built. Meanwhile, he also succeeded in building an Observatory at the summit of Mont-Blanc.

The story of this untiring and stubborn globe-trotter is enriched by extracts of the unpublished correspondence with his wife. One can thus understand why Henriette often complained of the solitude in which she was left by her peripatetic husband: There are men who leave their wives for mistresses; you do it for journeys ...

Basking in the glow of his success, Janssen was able to undertake the construction of the great astrophysical observatory of which he had dreamed. It was at Meudon that he had it built."