The idea of this colloquium was first put forward by Prof. P. Keenan when he visited the Centre de Donnees Stellaires, in September 1982. Dr. A. Florsch, Director of the Strasbourg Observatory, kindly accepted to field it at Strasbourg. The scientific organization of the colloquium was in charge of a Committee chaired by Prof. P.C. Keenan and composed by M. Feast, A. Florsch, B. Gustafsson, D. Harmer, M. Jaschek (secretary), R. McClure, A. Maeder, W. Straizys and T. Tsuji. The members of the Committee helped to translate the idea into a very successful meeting. It should be added that this colloquium was the first meeting devoted to late-type peculiar stars. The program was organized by sessions devoted to the following topics : taxonomy, photometric properties, distribution and space motions, chemical com- position, model atmosphere, binary systems and evolutionary tracks. Each session started with a review paper, followed by contributed papers presented as posters. The different sessions were chaired by W. Bidelman, R. Cayrel, Ch. Cowley, A. Heck, H.R. Johnson, J.P. Kaufmann and T. Tsuji, who did an excellent job. The President of the "Louis Pasteur University of Strasbourg", Prof. H. Duranton, welcomed the participants to the University where the sessions were held; Dr. A. Florsch welcomed the participation on be.balf of the French astrono- mical community and Prof. P. Keenan spoke on behalf on the Scientific Organizing Committee.

Adriaan Blaauw; Emeritus Professor of Astronomy at the Universities of Groningen and Leiden, former Directo.r of the Kapteyn Laboratory and of the European Southern Observatory, celebrated his 70th anniversary on 12 April 1984. To mark this event, an international Symposium was con- vened on the subject "Birth and Evolution of Massive Stars and Stellar Groups", a subject which has played the leading role in Blaauw's scien- tific research. The present volume contains the Scientific Proceedings of that Symposium. The meeting was organized by a Committee consisting of: W.H.W.M. Boland (Secretary), W.N. Brouw, W.B. Burton, E.P.J. van den Heuvel, H. van der Laan and H. van Woerden (Chairman). Together, these six persons represented the Executive Committees of the Netherlands Foundation for Astronomical Research (ASTRON) and the Netherlands Foundation for Radio Astronomy (RZM), two organizations in which Blaauw has held key offices. The scientific program was planned in full consultation with Adri- aan Blaauw himself. Only section 5, "A profile of Adriaan Blaauw", was kept secret to him. The other four sections: Structure of star-forming regions, Stellar content of young groups, Evolution of massive stars, and Extragalactic perspective on star formation, each represent an im- portant aspect of the overall theme of the Symposium. The program in- cluded 6 major review papers, 18 invited papers, 17 contributed papers, some of which were given as posters, and ample time for discussion.

If Zdenek Kopal Department of Astronomy University of Manchester Your Magnificences, my Lord Mayor, ladies and gentlemen! It is a great pleasure for me to respond, on behalf of your foreign guests, to your gracious words of welcome; and to thank you for the wonderful reception which you nave extended to us. The city of Bamberg and its Remeis Sternwarte nas indeed been renowned allover the world for a great many years - as the place where your Observatory's first director, Professor Ernst Hartwig (1851-1923) - in addition to his other titles to fame - collaborated (with Gustav Muller of Potsdam) on the construc- tion of the monumental Geschichte und Literatur des Lirhtwechsels der Veranderlichen Sterne, which since 1918 has (together with its sub- sequent continuation) been a veritable vade-mecum of a1l students of variable stars; where the second director, Professor Ernst Zinner (1886-19]~ prepared his valuable Katalog der Verdachtigen Veranderlichen Sterne (192@ which safeguarded many an astronomer (including the present speaker in the days of his innocence) from premature discovery claims; and whose third director, Professor Wolfgang Strohmeier, initiated in 1959 the tradition of the international colloquia of which ours is the latest successor. It is indeed a great pleasure to welcome Professor Strohmeier - now Emeritus - among us; and to congratulate him on the grace with which he is carrying his years.

This volume contains the papers and discussions at IAU Colloquium No. 21 on Variable Stars in Globular Clusters and in Related Systems held in Toronto on the 29th, 30th and 31st August 1972. It was the intention of the organizers that this meeting should honour the life long work in this field of Professor Helen Sawyer Hogg. She has been continuously active in observational research on variables in globular clusters for 46 years and her catalogues and bibliographies as well as her research papers, review articles and IA U reports as chairman of the committee on variable stars in clusters are of fundamental importance to all workers in this field. The scope of the colloquium covered both observational and theoretical aspects of the problem, including the relationship of variables to non-variable cluster members, the position of the variables in the HR diagram and their importance for problems of stellar evolution, empirical data on the variables, periods and period changes, and the relevant parts of pulsation theory. The meeting was particularly successful in bringing together observers and theorists. It will have achieved its object if it has shown both observers and theorists which are the problems most suitable for attack at the present time. The meeting clearly demonstrated the great importance of research on variables in globular clusters and related systems for our understanding both of stellar evolution and stellar pulsation.

This book is the result of a meeting held in August, 1986 in Irsee, West Germany. As the title suggests, the aim of the meeting was to discuss physical processes in interstellar clouds, determine the current status, aims and future direction of the research in this area. Interstellar clouds contain nearly all the mass of diffuse gas in our galaxy, some 10% of the total galactic mass. They represent the birth site for stars and the final "dumping ground" for matter ejected from stars (winds, ex plosive ejecta) and thus play an integral part in the galactic recycling of material. Not only are the clouds important for the structure and evolution of our galaxy, they are also interesting objects of study "per se." Because of their vast scales (up to about 100 parsec), extreme temperatures (as low as about lOOK), and long life 8 times (estimated a about 10 years) a number of physical and chemical processes occur in these environments, which we are not able to study elesewhere, certainly not in laboratories. It is for this reason that the meeting, and hence this book, was organized in such a way that firstly the latest observational results were sum m ized, going from the global, large scales, to finer details and dynamics, then progressing onwards to the processes -dynamical, chemical, electromagnetic, etc."

This book contains the lectures presented at the Summer Advanced Study Institute, 'Earth's Particles and Fields' which was held at the University of Sheffield, England, during the period August 13-24, 1973. One hundred thirty nine persons from sixteen different countries attended the Institute. The authors and publisher have made a special effort for rapid publication of an up-to-date status of the particles, fields, and processes in the Earth's magnetosphere, which is an ever changing area. Special thanks are due to the lecturers for their diligent preparation and excellent presentations. The individual lectures and the published papers were deliberately limited; the authors' cooperation in conforming to these specifications is greatly appreciated. The contents of the book are organized by subject area rather than in the order in which papers were presented during the Institute. Many thanks are due to Drs Rolf Bostrom, J. Ronald Burrows, Robert W. Fredricks, Thomas R. Kaiser, Bernt N. Maehlum, Christopher T. Russell, and Martin Walt who served as session chairmen during the Institute and contributed greatly to its success by skillfully directing the discussion period in a stimulating manner after each lecture.

It is sometimes said that astronomy is the crossroads of physics. In the same spirit, it can forcefully be argued that galaxies are the crossroads of astronomy. Internal pro ces ses within galaxies involve all of the fundamental components of astrophysics: stellar evolution, star formation, low-density astrophysics, dynamics, hydrodynamics, and high-energy astrophysics. Indeed, one can hardly name an observational datum in any wavelength range on any kind of celestial object that does not provide a useful clue to galaxy formation and evolution. Although internal processes in galaxies until recently occupied most of our attention, we now know that it is also vital to relate galaxies to their environment. How galaxies congregate in larger structures and are in turn influenced by them are crucial questions for galactic evolution. On a grander level we have also come to regard galaxies as the basic building blocks of the universe, the basic units whereby the large scale structure of the universe is apprehended and quantified. On a grander level still, we also believe strongly that galaxies are the direct descendents of early density irregularities in the Big Bang. Galaxy properties are now viewed as providing a crucial constraint on the physics of the Big Bang and a vital link between the macroscopic and microscopic structure of the universe."

The International Association of Geochemistry and Cosmochemistry was organized in 1967, and held its first meeting at UNESCO Headquartels that year in association with its symposium on The Origin and Distribution of the Elements'. The Association is a member of the International Union uf Geological Sciences, and holds regular meetings at the time of the I nternatlOnal Geological Congresses, the last of which was held in Montreal, in August. 1972. The IAGC was organized to coordinate activities on an international scale in a wide variety of branches of geochemistry. Its activities are carried on through Commissions and Working Groups, and by means of symposia and other international activities. It has national, corporate, and individual members. One of the first actions taken by the Council of the AGC when it met in 1967 was to establish an initial set of Working Groups to commence the activity of the organization. Among these Working Groups was one on Extraterrestrial Chemistry, established under the chairmanship of the writer. This Working Group recognized that its basic concern with the chemical composition of cosmic systems was a problem with ramifications in many fields in addition to geochemistry. The other scien tific disciplines which are involved include physics, astronomy and astrophysics, and geophysics. The Working Group thus included scientists in these disciplines from the beginning; many of the scientists had already participated in the first symposium of the IAGe. The Working Group has recently been elevated to the status of a Commission."

Colloquium No. 72 of the International Astronomical Union covered many observations and theoretical developments in the field of cataclysmic variables and related objects. Much time was devoted to discussions and we made an effort to include as much of the discussions material as possible in the proceedings. The Local Organizing Committee would like to thank; The International Astronomical Union for travel grants The Israel Academy of Sciences for financial support The Technion-Israel Institute of Technology for financial support and assistance Bank Leumi Le-Israel for a generous support We also thank the Dean of the Faculty of Physics, our colleagues and students for their assistance. MARIO LIVIO GIORA SHAVIV SCIENTIFIC ORGANIZING COMMITTEE B. Warner (Chairman), G.T. Bath, D. Crampton, J.E. Pringle, E.L. Robinson, G. Shaviv, R.E. Williams, J. Smak LOCAL ORGANIZING COMMITTEE G. Shaviv (Chairman), A. Finzi, M. Livio, H. Netzer, 0, Sadeh LIST OF PARTICIPANTS BATH, Geoffrey, T. Dept. of Astrophysics, Oxford, England BIANCHINI, Antonio Osservatorio Astronomico, Padova, Italy BROWNLEE, Robert, R. Los Alamos, New Mexico, U.S.A. CHANMUGAM, Ganesh Dept. of Physics and Astronomy, Louisiana State University, U.S.A. COLVIN, Jeff EG&G, Los Alamos, U.S.A. COWLEY, Anne, P. Dominion Astrophysical Observatory, Canada CRAMPTON, David Dominion Astrophysical Observatory, Canada EGGLETON, Peter P. Institute of Astronomy, Cambridge, England EVANS, A. Dept. of Physics, University of Keele, United Kingdom FEINGOLD, Susan J. Dept. of Physics, Technion, Israel FINZI, A.

Astrophysical analysis relating to solid matter requires data on properties and processes. Such data, however, expecially appropriate to space conditions are mostly lacking. It appeared then very tempting to gather together experimentalists, ob servers and theoreticians working in the field of cosmic dust and in related areas. The Workshop held in Capri (Italy) from September 8th till 12th 1987 gave the participants a unique opportunity for exchange of ideas and discussions of problems and experimental procedures. Introductory reports were prepared with the aim of giving the state of the art about single subjects; contributed poster papers presented, on the contrary, very recent results in the various fields. According to his specific interest each attendant has also contributed to three Working Groups respectively on a) carbon, b) silicates, c) ice and related topics. Scientifical and technical problems about these items were discussed in great detail. Though no definite answers were given, useful indications come out which will be of some help for future works. In addition to the scientific efforts, the Capodimonte Observatory and the Istituto Universitario Navale sought to give a warm welcome to the participants. Thanks to several sponsors, the LOC could organize some excursions and shows to entertain people during their spare time."

X-ray astronomers discovered the diffuse gas in clusters of galaxies about 20 years ago. It was later realized that the central gas density in some clusters, and in elliptical galaxies, is so high that radiative cooling is a significant energy loss. The cooling time of the gas decreases rapidly towards the centre of the cluster or galaxy and is less than a Hubble time within the innermost few hundred kiloparsecs. This results in a cooling flow in which the gas density rises in order to maintain pressure to support the weight of the overlying gas. The rate at which mass is deposited by the flow is inferred to be several hundreds of solar masses per year in some clusters. The fraction of clusters in which cooling flows are found may exceed 50 per cent. Small flows probably occur in most normal elliptical galaxies that are not in rich clusters. The implications of this simple phenomenon are profound, for we appear to be witnessing the ongoing formation of the central galaxy. In particular, since most of the gas is undetected once it cools below about 3 million K, it appears to form dark matter. There is no reason why it should be detectable with current techniques if each cooling proton only recombines once and the matter condenses into objects of low mass.

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 publication of this book is extremely timely, for the next major advances in manned space flight after Project Apollo will most likely be made in earth orbital operations. Manned exploration of the moon will certainly continue after the initial landing, but it will be performed essentially with the Saturn V launch vehicles and Apollo spacecraft developed in Apollo, especially in the early phases. Modifications to this basic hardware will increase operating capabilities to permit extensive lunar explo ration during prolonged stay times by the astronauts on the moon's surface. Manned orbital space stations have been studied for years, and NASA is already well along in development of its first attempt to provide more spacious accommo dations for astronaut-scientists in its Saturn Workshop program. While the Workshop is certainly not the ultimate space station of which our technology is capable, it is a workable, poor man's approach to the immediate need for using and expanding our present manned space flight capability without a de trimentalloss of momentum. The approach of converting a Saturn rocket stage into a manned laboratory and observatory in space is an improvisation that matches the use of the jerry-built Jupiter C back in 1958 to launch Explorer I. Let's hope that it can get the job done just as effectively."

Since 1976 a meeting devoted to recent research on cataclysmic variables ("CV workshop") has been held annually somewhere in North America. Many of the meetings have been held - following a custom older than anyone reading this book - in locations with well-known recreational potential (e. g. Santa Cruz, CA; Boulder, CO). We thought hard about this custom while contemplating the possibility of organi zing a meeting in Massachusetts in the middle of winter. Nobody wants their meeting to go down in history as the smallest and dullest, and it ~ surely be the coldest. But on occasion, meeting organizers have defied custom and scheduled meetings for less~than-trendy places, and gotten away with it (Ur*bana, IL and Rochester, NY must be reckoned as examples of this). Encouraged by the spatial and temporal proximity of the American Astronomical Society meeting (Boston, January 9-12), we thought we might get away with it again, and so came to organize a meeting for January 12-15, 1983, in Cambridge, MA. There was another reason for a meeting at this time and place, we loftily proclaimed in early mailings. No one doubts that the CV's are closely related to the low-mass X-ray binaries ("LMXB' s"), in which the accreting star is usually, or perhaps always, more compact than a white dwarf. Many of the general characteristics of LMXB's sound pretty familiar to any student of CV's: orbital periods in the range 0.

OPENING ADDRESS XI LIST OF PARTICIPANTS XV SESSION 1 THE ATMOSPHERE AND IONOSPHERE BELOW 150 km L. Thomas SOME OUTSTANDING PROBLEMS IN THE NEUTRAL AND IONIZED ATMOSPHERE BETWEEN 60 AND 150 km ALTITUDE 3 Peter M. Banks HIGH-LATITUDE IONOSPHERE-ATMOSPHERE INTERACTIONS (Abstract) 19 V. Domingo SOLAR RADIATION VARIATION AND CLIMATE 21 R. Bernard MAREES ET ONDES PLANETAIRES DANS LA BASSE THERMOSPHERE ET LA HAUTE MESOSPHERE 43 Michel Blanc and Paul Amayenc CONTRIBUTION OF INCOHERENT SCATTER RADARS TO THE STUDY OF MIDDLE AND LOW LATITUDE IONOSPHERIC ELECTRIC FIELDS 61 SESSION 2 THE OZONOSPHERE T. M. Donahue BASIC PROCESSES IN THE STRATOSPHERE AND THE MESOSPHERE (Abstract) 93 VI TABLE OF CONTENTS Ivar S. A. Isaksen CHEMICAL MODELS OF THE NEUTRAL ATMOSPHERE 95 M. Ackerman MEASUREMENTS OF MINOR CONSTITUENTS IN THE STRATOSPHERE 107 A. Vidal-Madjar, R. G. Roble, W. G. !iankin,G. Artzner, R. M. Bonnet, P. Lemaire, and J. C. Vial HIGH-RESOLUTION ATMOSPHERIC EXTINCTION MEASUREMENTS FROM THE FRENCH EXPERIMENT ON BOARD THE NASA SPACECRAFT OSO-8 117 M. Anderegg, J. E. Beckman, A. F. M. Moorwood, H. H. Hippelein, J. P. Baluteau, E. Bussoletti, A. Marten, and N. Coron HIGH-R~rOLUTION ATMQrPHERIC EMISSION SPECTROSCOPY AT 120 cm AND 535 cm WITH A RAPID-SCAN INTERFEROMETER AND 91 cm AIRBORNE TELESCOPE 129 Erwin Schanda, Joachim Fulde, and Klaus Kunzi MICROWAVE LIMB SOUNDING OF STRATOSPHERE AND MESOSPHERE 135 SESSION 3 METEOROLOGY IN THE IONOSPHERE AND STRATOSPHERE Hans-Jurgen Bolle CRITICAL CLIMATE PARAMETERS AND THEIR MONITORING FROM SPACE 149 R. J. Murgatroyd, A. O'Neill, and S. A.

In recent years it has become apparent that con tributions to our knowledge about the interstellar medium are made by practically all forms of astronomy ranging from radio- to gamma ray observations, and from cosmic ray measurements. It was thus thought fruitful to arrange for an interdisciplinary meeting of astron omers from the various fields of investigation, and of high energy astrophysicists. This meeting took place at Schliersee (Bavaria) from April 2 to 13, 1973. Lectures and some of the discussions held during that Advanced Study Institute are reproduced here. unfortunately, no manuscripts of the two lectures about infrared and cosmic ray observations were re ceived and these are thus not available here. However, it was thought to be more important to proceed now with the publication. The organisers are very grateful to Miss H. Eichele for her technical help during the meeting. The or ganisation of the Institute and the publication of the proceedings would have been impossible without the very great efforts and help of Mrs. M. Brunner and Mrs. D.Preis. I would also like to express my gratitude to my col leagues K.W. Michel and S. Drapatz for their many con tributions towards the success of the meeting."

If you want to understand the invisible, look careful at the visible. The Talmud A 'bird's eye' or rather a distant spacecraft's view of the solar system reveals an assembly of planets, terrestrial, giant and Pluto. The orbital motions are in the same sense, counter clockwise, as seen from the north of the general flattened space within which the planetary motions are confined. This state of affairs is corevolving and, more or less, coplanar. The rotations are in the same sense as the revolutions, with the strikiiig exception of Uranus whose sense of rotation is perpendicular to its plane of revolution. As time goes by, most of the planets remain fairly close to a general plane and at no time stray unduly far from it; they remain confined within a rather narrow box or disk with a large 'equatorial' extent. The most distant planet, Pluto, requires a diameter of some 80 astronomical units for the disk. One astronomical unit is the distance of the Earth to the Sun, to be more precise the length of half the major axis of the Earth's slightly elliptical orbit around the Sun, and amounts to nearly 149600000 km.

On the occasion of the International Conference on Cosmic Rays held in Kyoto in August 1979 five aged members of the cosmic ray fraternity, H. Elliot, V. L. Ginzburg, B. Peters, Y. Sekido, and J. A. Simpson met together as a dinner party devoted to the enjoyment of Japanese cuisine and reminiscences of our younger days. This pleasant occasion called to of our own age as well as some eminent seniors not present at the mind the many friends conference whose recollections would have further enriched and enlivened our evening. By the time the dinner came to an end we had agreed that the compilation of a more extensive collection of personal reminiscences would be an interesting and worthwhile undertaking. Accordingly, the next day we held an editorial meeting to draw up a list of potential authors and two of us, the present editors, started work on the project. In putting the book together our intention has been to try to capture and record through these personal accounts something of the atmosphere, the excitement and the frustrations of research in cosmic rays as experienced at first hand by some of the practi tioners in the field. It has never been our intention that it should comprise a systematic history of the subject. Neither, unfortunately, can it be a fully representative collection since practical limits to the size of the volume alone would preclude that."

This publication, in two volumes, includes most of the scientific papers presented at the first meeting of the International Society for the Study of the Origin of Life (ISSOL), held on June 25-28, 1973 in Barcelona, Spain. The first volume contains the invited articles and the second volume the contributed papers, which also appear in the 1974 and 1975 issues, respectively, of the new journal Origins of Life, published by D. Reidel. A relatively large number of meetings on the subject of the origin of life have been held in different places since 1957. In terms of its organization, scope, and number and nationality of participants, the Conference celebrated last year in Barcelona closely followed the three international conferences held earlier in Moscow, U.S.S.R., 1957, Wakulla Springs, U.S.A., 1963, and Pont-a-Mousson, France, 1970. For this reason the first ISSOL meeting was also named the Ath International Conference on the Origin of Life.

The idea to hold a conference on the Evolution of Close-Binary X-ray sources grew in the summer of 1984. At that time we were hoping that some new results would be harvested in the months to come which would stimulate further work. We were particularly looking towards the Euro pean X-ray Observatory, EXOSAT, for new contributions. How lucky we were; quite unexpected developments took place. Just prior to the conference, quasi-periodic oscillations (now known as QPO) were discovered in three bright low-mass X-ray binaries: GX 5-1, Sco X-1, and Cyg X-2. They played an important role at the meeting. The possibility that QPOs imply a neutron star magnetic dipole field, and a neutron star rotation period in the millisecond range, received a lot of attention. This is not surprising, as it lends support to the idea, suggested earlier, that the 6-msec binary radio pulsar PSR 1953+29 evolved from a stage in which it was a bright low-mass X-ray binary. There was special interest in the possibility of white dwarf collapse into a neutron star. This is a. particularly attractive way to form the bright low-mass X-ray binaries, often referred to as galactic bulge sources. It would allow for the possibility of a very young neutron star in a very old binary system. The relatively high magnetic fields that one could infer from QPO could then be explained."

The year 1973 marked the highest peak of IAU activity up to now. Besides the Gen eral Assembly in Sydney, and the Extraordinary General Assembly in Poland, there were held eleven IAU Symposia and one Colloquium. Several IAU Publications cover this activity. The Proceedings of the Symposia are published in separate Volumes, while the Transactions of the General Assembly and of the Extraordinary General Assembly contain short reports of the Commission meetings, the administrative sessions, and the opening ceremonies. The present Volume covers some of the scientific Highlights of the General As sembly and of the Extraordinary General Assembly. It contains five Invited Dis courses given in Sydney and Poland, some selected papers, and the Joint Discussions at the General Assembly of Sydney. Of course, there were many more papers of special interest presented in Sydney that could not be included in this Volume. Their titles can be seen in the reports of the various Commissions. It is regrettable that the Invited Discourses of C. H. Townes (Interstellar Molecules) and F. J. Low (Infrared Astronomy) were not submitted for publication. Also only five papers or abstracts of the Joint Discussion on the 'Origins of the Moon and Satellites' have been available. Despite these minor shortcomings, I believe that the present Volume is faithful to its title: it gives a substantial part of the Highlights of Astronomy in 1973.

The aim of the present book will be to provide a comprehensive account of our present knowledge of the theory of dynamical phenomena exhibited by elose binary systems; and on the basis of such phenomena as have been attested by available observations to outline probable evolutionary trends of such systems in the course of time. The evolution of the stars - motivated by nuelear as weIl as gravitation al energy sources - constitutes nowadays a well-established branch of stellar astronomy. No theo ries of such an evolution are as yet sufficently specific - let alone infallible - not to require continual tests by a confrontation of their consequences with the observed prop erties of actual stars at different stages of their evolution. The discriminating power of such tests depends, of course, on the range of information offered by the test objects. Single stars which move alone in space are now known to represent only a minority of objects constituting our Galaxy (cf. Chapter 1-2); and are, moreover, not very revealing of their basic physical characteristics - such as their masses or absolute dimensions. If there were no binary systems in the sky, the only star whose vital statistics would be fully known to us would be our Sun.

IX LIST OF PRINCIPAL SPEAKERS XI LIST OF PARTICIPANTS 1. REGULARIZATION E. STIEFEL / A Linear Theory of the Perturbed Two-Body Problem (Regul- ization) 3 J. WALDVOGEL / Collision Singularities in Gravitational Problems 21 D. C. HEGGIE / Regularization Using a Time-Transformation Only 34 J. BAUMGAR TE / Stabilization of the Differential Equations of Keplerian Motion 38 F. NAHON / The Particular Solutions of Levi-Civita 45 O. GODAR T / Example ofIntegration of Strongly Oscillating Systems 53 w. BLACK / The Application of Recurrence Relations to Special Perturbation Methods 61 D. G. BETTIS / Numerical Solution of Ordinary Differential Equations (Abstract) 71 II. THE THREE-BODY PROBLEM V. SZEBEHELY / Recent Advances in the Problem of Three Bodies 75 R. F. ARENSTORF / Periodic Elliptic Motion in the Problem of Three Bodies (Abstract) 107 G. KATSIARIS and c. L. GOUDAS / On a Conjecture by Poincare 109 G. KATSIARIS / The Three-Dimensional Elliptic Problem 118 P. G. KAZANTZIS / Second and Third Order Variations of the Three Dimensional Restricted Problem 135 c. G. ZAGOURAS / Planar Periodic Orbits Using Second and Third Variations 146 E. RABE / Elliptic Restricted Problem: Fourth-Order Stability Analysis of the Triangular Points 156 P. GUILLAUME / A Linear Description of the Second Species Solutions 161 III. THE N-BODY PROBLEM AND STELLAR DYNAMICS G. CONTOPOULOS / Problems of Stellar Dynamics 177 w. T. KYNER / Invariant Manifolds in Celestial Mechanics 192 s. J.