COMPENDIUM IN ASTRONOMY

PROFESSOR JOHN XANTHAKIS

FELLOW OF THE NATIONAL ACADEMY OF ATHENS SECRETARY OF THE PROCEEDINGS OF THE ACADEMY

EMERITUS PROFESSOR OF ASTRONOMY AT THE UNIVERSITY OF THESSALONIKI

COMPENDIUM IN

ASTRONOMY A Volume Dedicated to Professor John Xanthakis

on the Occasion of Completing Twenty-five Years of Scientific Activities as Fellow of the National Academy of Athens

Edited by

ELIAS G. MARIOLOPOULOS Fellow, National Academy of Athens

President, National Observatory of Athens

PERICLES S. THEOCARIS Vice·President, National Academy of Athens

Rector, National Technical University of Athens

and

L. N. MAVRIDIS Professor, University of Thessaloniki

D. REIDEL PUBLISHING COMPANY

DORDRECHT : HOLLAND / BOSTON: U.S.A.

LONDON: ENGLAND

library of Congress Cataloging in Publication Data Main entry under title:

Compendium in astronomy.

Includes indexes. 1. Astronomy-Addresses, essays, lectures.

Clp

2. Xanthakis, John N., 1904- -Addresses, essays, lectures. John N., 1904- II. Mariolopoulos, Elias G., 1900-

I. III.

Xanthakis, Theocaris,

Pericles S., 1921- IV. Mavridis, L. N. V. Series. QB51.C686 520 ISBN-13: 978-94-009-7768-6 e-ISBN-13: 978-94-009-7766-2 DOl: tO.1 007/978-94-009-7766-2

81-19949 AACR2

Published by D. Reidel Publishing Company, P.O. Box 17,3300 AA Dordrecht, Holland.

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All Rights Reserved Copyright © 1982 by D. Reidel Publishing Company, Dordrecht, Holland

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PREFACE

When we first approached some colleagues allover the world to sound them about a volume dedicated to Professor John Xanthakis on the occasion of completing twenty-five years of scientific activities as fellow of the National Academy of Athens, any possible doubts as to the feasibility of the project were quickly dispelled by their warm and encouraging response. In a short time 50 authors from 15 countries, coming from a wide range of Professor Xanthakis' immediate colleagues, pupils and friends joined to produce the 36 contributions included in this volume.

Some of those who where originally approached found themselves un­able to contribute, because of the time-limit necessarily imposed. Happi­ly, they were only few in number, and we should like to record our grat­itude to them for their good wishes for the success of the venture. Their warm words were among the many sources of inspiring encouragement extended to us.

This response can easily be understood, if one takes into account the career, scientific achievements and personality of Professor Xantha­kis, which made him a widely known and highly estimated member of the international scientific community. His research work, which opened new perspectives in the fields of Solar Physics and Solar-Terrestrial Rela­tions, his pioneer work as the first Professor of Astronomy at the Uni­versity of Thessaloniki, his long and creative scientific activity as Fellow, Secretary of the Proceedings, and President of the National Acad­emy of Athens, where he founded, as early as twenty years ago, the Re­search Center for Astronomy and Applied Mathematics, as well as his con­tinuous efforts in his capacity as President of the Greek National Com­mittees for Astronomy, for Mathematics and for Space Research, to ensure the harmonious co-operation of the Greek scientists in the international scientific programs, had already, long ago, created the proper climate for this enthousiastic response to our request.

It is our pleasant duty to extend our warmest thanks to all those who contributed to the preparation of the present volume. First of all to the authors of the papers for their excellent co-operation. Then to the publishers, the D. Reidel Publishing Company, for their unfailing helpfulness and great care, which they devoted to the production and publication of this volume, especially to Mrs. N.M. Pols-v.d. Heijden, who always gave every possible consideration to our suggestions. Finally, to Miss J. Karrinti, who assisted us in man" ways during the preparation of the volume, and Hrs. E. Kolokotroni and Hiss M. Stamatelou, who typed the camera-ready manuscript.

v

E. G. Mariolopoulos et al. (eds.), Compendium in Astronomy, v-vi. Copyright © 1982 by D. Reidel Publishing Company.,

PREFACE

We should like to add a final personal footnote to our Preface. Circumstances have qiven us the opportunity of long-continued contact with Professor Xanthakis' inspiring personality. It is an experience, which we cherish more deeply than we can readily express, and which we consider one of the greatest gifts of our life.

August 1981 E.G. MARIOLOPOULOS P.S. THEOCARIS L.N. MAVRIDIS

PROFESSOR JOHN XANTHAKIS BRIEF BIOGRAPHICAL NOTE AND LIST OF PUBLICATIONS

BRIEF BIOGRAPHICAL NOTE

Born in Gythion, Greece, November 21, 1904. Graduate in Mathematics, University of Athens (1925); PhD in Mathematics, University of Athens (1930). Astronomer and Chief Assistant, University of Athens (1929-31). Research Associate, Observatoire de Strasbourg (1931-34). Professor of Mathematics, Military Academy of Athens (1938-39). Professor of Astronomy, University of Thessaloniki (1939-55). Fellow, National Academy of Athens (1955-now); President National Acad­emy of Athens (1964); Secretary of the Proceedings, National Academy of Athens (1966-now). Founder and Supervisor of the Research Center for Astronomy and Applied Mathematics, National Academy of Athens (1959-now). President, Greek National Committee for Astronomy (1957-now). President, Greek National Committee for Mathematics (1957-80). President, Greek National Committee on Space Research (1964-now). President, Administrative Council, Greek Oceanographic Institute (1960-671. President, Greek Mathematical Society (1965-73). Served twice as Minister of Agriculture (1963,1964). Published 6 text-books in Greek language, 2 books and 78 original papers. His research work refers mainly to the Mathematical Analysis, Positional Astronomy, Solar Physics and Solar-Terrestrial Relations.

BOOKS

1. Solar Physics, Proceedings of a NATO Advanced Study Institute Confer­ence, Athens, September 1965, (ed. by J. Xanthakis), Interscience Publishers a Division of John Wiley and Sons, London, New York, Sydney, 1967.

2. Solar Activity and Related Interplanetary and Terrestrial Phenomena, Proceedings of the First European Astronomical Meeting, Athens, September 4-9, 1972, Vol. I, (ed. by J. Xanthakis), Springer-Verlag, Berlin, Heidelberg, New York, 1973.

TEXT-BOOKS (in Greek)

1. General Mathematics, University of Thessaloniki Press, Thessaloniki, 1947.

vii

E. G. Mariolopoulos et al. (eds.), Compendium in Astronomy, vii~xii. Copyright © 1982 by D. Reidel Publishing Company.

viii BIOGRAPHICAL NOTE AND LIST OF PUBLICATIONS

2. Probability Calculus, University of Thessaloniki Press, Thessaloniki, 1951.

3. Astronomy, Vol. I: Spherical Astronomy, University of Thessaloniki Press, Thessaloniki, 1955.

4. Astronomy, Vol. II: Celestial Mechanics, University of Thessaloniki Press, Thessaloniki, 1952.

5. Astronomy, Vol. IlIa: Earth, Moon, Sun. University of Thessaloniki Press, Thessaloniki, 1954.

6. Astronomy, Vol. IV: Stellar Astronomy, University of Thessaloniki Press, Thessaloniki, 1951.

ORIGINAL PAPERS

1 .. Sur la theorie des anomalies des equations differentiel1es du 1er ordre, Proc. Acad. Athens, 5, 53, 1930.

2 .. Contribution a la theorie de; singu1arites des equations differentiel­les du premier ordre.PhD Dissertation, University of Athens, 1930.

3. Sur les singularites des equations differentielles du premier ordre. Ann. Fac. Sci. Univ. Toulouse, 1932.

4. Sur la variation des longitudes geographiques, Proc. Acad. Athens I, 255, 1932.

5. Sur Ie terme Z de M. Kimura, Proc. Acad. Athens, ~, 32, 1933. 6. Sur les deplacements apparents de l' etoile po1aire, Compt. Rend.

Acad. Sci. Paris 196, 1649, 1933. 7. Sur les fluctuatio~du meridien de Greenwich, Bull. Astron. Obs.

Paris 8, Fasc. III, 123, 1934. 8. Sur quelques erreurs systematiques des ascensions droites des etoiles

circumpolaires, Proc. Acad. Athens 9, 136, 1934. 9. Sur la variation diurne des aZimuts,-Proc. Acad. Athens 11, 46~ 1936.

10. Observations de l' eclipse totale de soleil du 19 Juin 1936. Mem. Natl. Obs. Athens, Ser. I. Astron., No.1, 20, 1937.

11.. Sur 1es causes de la variation des azimuts, Proc. Acad. Athens 12, 478, 1937.

12. Sur la variation d'azimut de la ligne des mires meridiennes a l'Obser­vatoire de Strasbourg, Compt. Rend. Acad. Sci. Paris 206, 171, 1938.

13. Sur une relation remarquable entre les temperatures moyennes mensuel­les de l'air a Alexandrie, Athenes, Rome, Paris, Proc. Acad. Athens 13,424,1938.

14. A New Method for the Determination of the Logistic Curve. Application to the Population of Greece, Proc. Acad. Athens 14,412, 1939.

15. Sur les temperatures moyennes mensuelles de l'air, Volume dedicated to the thirty-fifth anniversary from the appointment of Professor N. Criticos (1907-1942), p. 150, Athens, 1943.

16. Relation between the Mean Monthly Air Temperatures in the Temperate Zones, University of Thessaloniki Press, Thessaloniki, 1948.

17. Relation Between the Mean Monthly Air Temperatures in the Temperate Zones, BUll. Am. Meteorol. Soc. 29, 550, 1948.

18. Statistical Study of the Results of the Entrance Examinations to the Schools of the University of Thessaloniki during the Academic Years 1946-47, 1947-48, 1948-49, BUll. Univ. Thessaloniki, 1949.

BIOGRAPHICAL NOTE AND LIST OF PUBLICATIONS ix

19. Sur une relation entre les valeurs moyennes mensuelles de la radia­tion solaire observee en 12 stations de l' hemisphere nord, Proc. Acad. Athens 26, 208, 1951.

20. Sur la variation d' azimut du cercle meridien de l' Observatoire National d' Athenes, Bull. Hellenic Army Geographical Service 12, 1, 1952.

21. A Correlation Between the Coefficient of Continentality and the Excen­tricity of the Ellipse of the Mean Monthly Air Temperatures in the Temperate Zones, Proc. Acad. Athens 27, 101, 1952.

22. Justification theorique d' une relation empirique entre les valeurs moyennes mensuelles de la temperature de I' air et de la radiation solaire, Proc. Acad. Athens 27, 168~ 1952.

23. New Relations between the Mean Monthly Air Temperatures, University of Thessaloniki Press, Thessaloniki, 1953.

24. Sur la distribution symetrique des temperatures moyennes mensuelles de I' air, Proc. Acad. Athens 28, 47, 1953.

25. Les temperatures saisonnieres de l'air pendant les periodes de I' action solaire, Proc. Acad. Athens 28, 91, 1953.

26. Le probleme des deplacements apparents de I' etoile Polaire, Proc. Acad. Athens 28, 274, 1953.

27. Expression de la radiation solaire en fonction de la longitude du Soleil en 11 stations de I' hemisphere nord, Proc. Acad. Athens 28, 299, 1953.

28. Study of the Mean Monthly Air Temperatures during the Successive Sunspot Cycles, Publ. Astron. Dept. Univ. Thessaloniki No.1, 1955.

29. Sur les variations des temperatures saisonnieres de I' air a six stations de I' Europe Centrale et du Nord-Ouest pendant les 150 dernieres annees, Proc. Acad. Athens 30, 115, 1955.

30. Sur une correlation importante entre I' action solaire et I' atmo­sphere inferieure, Proc. Acad. Athens 30, 125, 1955.

31. Study of the Mean Monthly Air Temperatures during the Successive Sunspot Cycles, Archiv Meteorol. Geophys. Bioklimatol. Sere A 2.., 54, 1956.

32. Sur une classification des cycles des taches solaires et des facules, Astron. Zh. 34, 391, 1957.

33. Current Solar Studies. Inaugural Presentation in the Academy of Athens, Proc. Acad. Athens 32, 202, 1957.

34. Les aires des taches solaires et des facules en fonction du temps d' ascension, Geofis. Pura e Appl. Milano ~, 1, 1958.

35. The Areas of Sunspots in the Two Sun Hemispheres, Trans. Acad. Athens 24, 1, 1958.

36. L' expression de I' acti vite solaire en fonction du temps d' ascension Ann. Astrophys. 22, 855, 1959.

37. Les aires des taches solaires vers Ie Nord et vers Ie Sud de I' equateur du Soleil en fonctions du temps d' ascension. Compt. Rend. Acad. Sci. Paris 249, 1315, 1959.

38. L' asymetrie N-S dans I' activite solaire. Compt. Rend. Acad. Sci. Paris 249, 1458, 1959.

39. The Sunspot Areas and the Relative Sunspot Numbers.Geofis. Pura e Appl. Milano 46, 11, 1960.

x

40.

41.

42.

43.

44.

46.

48.

BIOGRAPHICAL NOTE AND LIST OF PUBLICATIONS

Sur les maximums singulierement eleves de I' activite solaire. Compt. Rend. Acad. Sci. Paris 253, 1311, 1961.

The Sunspot Areas and the Wolf Numbers. A Study of the Analytical Relations Given by J. Xanthakis and J. Mergentaler. Mem. Soc. Astron. Ital. XXXIII, 291, 1962. (in collaboration with G. Banos).

Les relations analytiques des nombres des groupes de taches solaires et de nombres relatifs. Ann. Astrophys. 25, 342, 1962.

Two Interplanetary Phenomena of 468 B.C. ,~rans. Acad. Athens 24, No.4, pp. 24-45, 50-53, 1963. (Marinatos, S., comments by J.-­Xanthakis) .

A Study of the Sunspot Magnetic Field Strengths, Mem. Soc. Astron. Ital. XXXVI, 25, 1965.

The Departures of the Maxima of Solar Activity from the Parabolic Law. Publicazioni del Comitato Nazionale per Ie Manifestazioni Celebrative del IV Centenario della Nascita di Galileo Galilei, Tomo 2: Atti del Convegno sulle Macchie Solari, pp. 63-67, 1966.

Probable Value of the Time of Rise for the Sunspot Cycle No. 20. Nature 210, 1242, 1966.

The Relative Sunspot Numbers and the Time of Rise. Bull. Astron.Inst. Czech. 17, 215, 1966.

The Probable Mean Values of the Different Indices of Solar Activity During the Sunspot Cycle No. 20 (1964-1975). Proc. Acad. Athens 41, 384, 1967.

The Different Indices of Solar Activity and the Time of Rise, in Solar Physics (ed. by J. Xanthakis), Interscience Publishers, London, N. York, Sydney, p. 157, 1967.

50. Probable Values of the Time of Rise for the Forthcoming Sunspot Cycles Nature, 215, 1046, 1967.

51. On a Relation Between the Indices of Solar Activity in the Photosphere and the Corona. Solar Phys. 10, 168, 1969.

52. Relations entre l' indice des aires, Ie nombre des eruptions a protons (proton flares), la variation du radio-diametre de la couronne solaire et l' intensite des rayons cosmiques. Compo Rend. Acad. Sci. Paris, 271, 1009, 1970.

53. On a Relation Between the Indices of Solar Activity in the Photosphere and the Corona, Proc. Acad. Athens 44, 153, 1970.

54. Relations Between the Areas Index and Different Phenomena in the Chromosphere, the Corona and the Interplanetary Space, in Physics of the Solar Corona (ed. by G. Macris), D. Reidel, Dordrecht-Holland, p. 179, 1971.

55. Solar Activity and Precipitation, in Solar Activity and Related Inter­planetary and Terrestrial Phenomena (ed. by J. Xanthakis), Springer­Verlag, Berlin p. 19, 1973.

56. Solar Activity and Precipitation Within the Zones of Latitude 00_40o N. Proc. Acad. Athens 49, 187, 1974 (in collaboration with C. Poulakos and B. Tritakis). --

57. Remarks on High Latitude Air Temperature Ranges and Solar Activity, Proc. Acad. Athens LQ., 118, 1975 (in collaboration with Ch. S. Zerefos).

58. Probable Periodical Variations in the Frequency of the Etesian Winds, in the Special Volume in Memoriam "Demetrios Eginitis", (ed. by C. Carapiperis, D. Kotsakis, and C. Macris), Athens p. 305, 1975.

BIOGRAPHICAL NOTE AND LIST OF PUBLICATIONS xi

59·

60.

61.

62.

64.

66. 67. 68.

Solar Activity and a Global Survey of the Precipitation. Trans. Acad. Athens 37, 1975.

Analytical Expression of the Mean Annual Variation of the Precipita­tion Within Various Latitude Zones of the Earth. Proc. Acad. Athens 51, 600, 1976 (in collaboration with B. Tritakis).

Analytical Expression of the Mean Annual Variation of the Precipita­tion Within Various Latitude Zones of the Earth. J. Interdiscipl. Cycle Res. ~, 226, 1977 (in collaboration with B. Tritakis).

Preliminary Results on the Discovery of Two Possible Galaxies in Cepheus. Proc. Acad. Athens 52, 230, 1977 (in collaboration with C. Poulakos). -

A Forecast of Solar Activity for the 21st Solar Cycle. Solar Phys. 56, 467, 1978 (in collaboration with C. Poulakos).

A Microdensitometer Tracing of a New Elliptical Galaxy in Cepheus. Proc. Acad. Athens 52, 620, 1977 (in collaboration with C. Poulakos).

A New Index of Solar~ctivity. Proc. Acad. Athens 53, 286, 1978 (in collaboration with C. Poulakos). --

Possible Sun-Weather Correlation. Nature 275, 775, 1978. Possible Sun-Weather Correlation II. Nature 280, 254, 1979. Prediction of the Radio Emission Indices of the Sun in the Frequency

Range 1000 MHz", f ~ 3750 MHz , in Solar Terrestrial Predictions Pro­ceedings Vol. 3: Solar Activity Predictions (ed. by R.F. Donnelly), U.S. Dept. of Commerce, NOAA, Environmental Research Laboratories, p. 75,1980 (in collaboration with C. Poulakos).

The Mean Annual Variation of the Precipitation and the Pressure in the Zone 00 _100 of the Northern Hemisphere, in Low Latitude Aeronom­ical Processes COSPAR Symp. Ser. Vol. 8 (ed. by A.P. Mitra) Pergamon Press, Oxford, N. York p. 245, 1980 (in collaboration with C. Pou­lakos and B. Tritakis).

70. On the Variation of the Annual Mean Sea-Level Pressure in Latitude Zones of the Northern Hemisphere, in Solar-Terrestrial Predictions Proceedings Vol. 4:Prediction of Terrestrial Effects of Solar Activ­ity (ed. by R.F. Donnelly), Space Environment Laboratory, Boulder,

71.

72.

73.

74.

75.

76.

Colorado, F-63, 1980. Influence of Solar Proton Event on Upper Stratospheric Temperatures. Proc. Acad. Athens 55, 362, 1980 (in collaboration with C. Zerefos, S. Sehra, C. Repapi;: C. Poulakos).

Cosmic-Ray Intensity Related to Solar and Terrestrial Activity Indi­ces in Solar Cycle No. 20. Astrophys. Space Sci., 74, 303, 1981. (in collaboration with H. Mavromichalaki and B. Petropoulos).

Effects du champ magnetique solaire sur l'intensite semi annuelle de la raie verte coronale. Soleil et climat, Toulouse, 30 Septembre-3 Octobre 1980. CNES, CNRS, DGRST, p. 101, 1980 (in collaboration with B. Petropoulos and H. Mavromichalaki).

The Evolution and the Secondary Maximum of the Corona Line Intensity. Solar Phys. (in press) (in collaboration with B. Petropoulos, H. Mavromichalaki) .

A Study of the Inferred I.J.F. Polarity Periodicities. J.I.C.R. (in press) (in collaboration with B. Tritakis and C. Zerefos).

Rocket Sonde-Derived Stratospheric Temperature Changes Associated with a Major Solar Cosmic Ray Event. Astrophys. Space Sci. 74, 475,

xii BIOGRAPHICAL NOTE AND LIST OF PUBLICATIONS

1981 (in collaboration with C.A. Zerefos, P. Sehra, C. Repapis and C. Poulakos).

77. Possible Periodicities of the Annually Released Global Seismic En­ergy (M ? 7.9) during the Period 1898 - 1971. Tectonophysics (in press) .

78. Possible Periodicities of the Annually Released Planetary Seismic Energy (M? 7.8) during the Period 1898-1977. Proc. Acad. Athens (in press).

TABLE OF CONTENTS

PROFESSOR JOHN XANTHAKIS: BRIEF BIOGRAPHICAL NOTE AND LIST OF PUBLICATIONS vii

PART I: HISTORY AND PHILOSOPHY

BATTEN, A.H.: Episteme and Gnosis. A Tension in European Thought 3 CIMINO, M.: A New, Rational Endeavour for Understanding the Era­

tosthenes Numerical Result of the Earth Meridian Measurement 11 TELEKI, G.: Astronomical Activity in the Period 1600 to 1880 23

PART II: DYNAMICS

BARBANIS, B.: The Behaviour of Adiabatic Invariants near Reso-nances 31

BOUVIER, P.: Radiation Pressure Effect on Dust Surrounding the Pleiades Bright Stars 43

CONTOPOULOS, G.: Trapping of Orbits in Barred Galaxies 55 HADJIDEMETRIOU, J.D.: On the Stability of the Asteroids 67

PART III: SOLAR PHYSICS

BUMBA, V~: Solar Magnetic Fields and Activity 81 GOKDOGAN, N., AVCIOGLU, K., and KOgER, D.: The Experimental

Curve of Growth in Function of Different Sets of Oscil-lator Strengths 97

KLECZEK, J. and OLMR, J.: Relations of Solar Activity Indices 105 KOPECKY, M.: Why the Total Solar Radio Flux at a Wave Length

of 10cm Cannot Fully Replace the Wolf Relative Sunspot Number 111

KRIVSKY, L.: Increasing Trena of Flare Activity Before the Proton Flare April 30, 1976 117

KUNDU, M.R.: Centimeter Wavelength Observations of Active Re-gions and Flares with a Few Arc Second Resolution 119

VITINSKY, Yu.I.: A Correlation Between Various Indices of So-lar Activity and Solar Cycles 139

xiv TABLE OF CONTENTS

PART IV: SOLAR-TERRESTRIAL RELATIONS

PECKER, J.-C.: Caracteres Meteorologiques du Clima~ et Activite Solaire: Quelques Remarques 151

ROBERTS, W.O. and OLSON, R.H.: A Suggested Approach to Research on the Sun-Weather Problem 161

PART V: PLANETARY SYSTEM

ASAAD, A.S.: Observations of Zodiacal Light in Egypt and its Variations 171

BIERMANN, L.: On the Global Size of Oort's Cloud of Cometary Nuclei and their Total Number 183

KRIMIGIS, S.M.: Voyager Encounters with Jupiter's Magnetosphere: Results of the Low Energy Charged Particle (LECP) Experiment 191

MACRIS, C.J. and PETROPOULOS, B.Ch.: The Weather on Mars on the Basis of the Measurements Carried out by the Vikings Mission 201

PART VI: STELLAR ASTRONOMY

AMBARTSUMIAN, V .A.: On the Origin of Nebulae 211 DALLAPORTA, N.: On Mass Loss from Stars 219 KOPAL, Z.: Contribution to Fourier Analysis of the Light Curves

of Eclipsing Variables 233 LACROUTE, P.: Prospective Views in Space Astrometry 247 MAVRIDIS, L.N., ASTERIADIS, G., and MAHMOUD, F.: Long-Term

Changes of the Flare Stars EV Lac and BY Dra 253 NIKOLOV, N.S. and IVANOV, G.R.: On the Problem of Cepheid Ampli-

tude Dependence on the Star Position in the Instability Strip 277 SVOLOPOULOS, S.N.: Early-Type Emission-Line Stars 285

PART VII: GALAXIES

BRUCK, M.T.: The Structure of the Small Magellanic Cloud 297 IWANOWSKA, W.: Large Scale Distribution of Elements and Gravity 315 KAFATOS, M., SHAPIRO, M.M., and SILBERBERG, R.: Active Galactic

Nuclei and Particle Accele.ration in Accretion Disks Around Massive Black Holes 323

PART VIII: COSMOLOGY AND RELATIVITY

ANTONACOPOULOS, G. and KOSTAKIS, C.G.: Non Linear Einstein-Maxwell Differential Equations 349

MORRISON, L.V.: Recent Results for the Moon's Secular Accelera-tion and their Implication for the Possible Variation of G in Dirac's Large Number Hypothesis 361

TABLE OF CONTENTS xv

PERSIDES, S.: Classical Phase Space from a Relativist's Point of View 367

PART IX: EXTRATERRESTRIAL INTELLIGENCE

PAPAGIANNIS, M.D.: The Colonization of the Galaxy. A Key Concept in the Search for Extraterrestrial Intelligence 38l

PART X: ASSOCIATED FIELDS

GOUDAS, C.L., KATSIARIS, G.A., DRYMONITOU, M.A., and VERNARDIS, A.J.: Numerical Treatment of the Magnetohydrodynamic Flow Bounded by an Infinite Porous Plate 393

THEOCARIS, P.S.: Ray Tracing and Caustics from Large Reflectors Used in Spacecrafts 415

NAME INDEX 447

SUBJECT INDEX 460