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Full Meridian Ofglory Full Meridian of Glory Perilous Adventures in the Competition to Measure the Earth Full Meridian of Glory Perilous Adventures in the Competition to Measure the Earth paul murdin ISBN: 978-0-387-75533-5 e-ISBN: 978-0-387-75534-2 DOI: 10.1007/978-0-387-75534-2 © Springer Science + Business Media, LLC 2009 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Published in the United States by Copernicus Books, an imprint of Springer Science+Business Media. Copernicus Books Springer Science + Business Media 233 Spring Street New York, NY 10013 www.springer.com Library of Congress Control Number: 2008939455 Manufactured in the United States of America. Printed on acid-free paper 9 8 7 6 5 4 3 2 1 I have touched the highest point of all my greatness; And from that full meridian of my glory I haste now to my setting. William Shakespeare King Henry VIII. Act iii. Sc. 2. Contents Introduction .................................................................................................... xi Chronology ..................................................................................................... xvii 1 The Incroyable Pique-nique and the Méridienne Verte ........................ 1 2 The Size of France .................................................................................. 11 3 Shape of the Earth ................................................................................. 39 4 The Meridian and the Sun ..................................................................... 77 5 The Revolution and the Meter .............................................................. 85 6 The Paris Meridian in the Napoleonic Wars ....................................... 111 7 Past its Prime .......................................................................................... 129 8 The Greenwich and Paris Meridians in the Space Age ...................... 143 9 On the Trail of The Da Vinci Code ........................................................ 149 10 Walking the Line: the Arago Memorial ............................................... 153 14th Arrondissement ................................................................................ 153 6th Arrondissement ................................................................................... 155 1st Arrondissement ................................................................................... 156 2nd Arrondissement .................................................................................. 158 9th Arrondissement ................................................................................... 158 18th Arrondissement ................................................................................. 158 14th Arrondissement ................................................................................. 159 6th Arrondissement ................................................................................... 161 1st Arrondissement ................................................................................... 164 vii viii Contents 2nd and 9th Arrondissements .................................................................... 166 18th Arrondissement ................................................................................. 166 Bibliography ................................................................................................... 169 Acknowledgements ........................................................................................ 173 Index ................................................................................................................ 175 List of Figures Fig. 1 Map of France ................................................................................... 4 Fig. 2 Méridienne Verte ............................................................................... 5 Fig. 3 Finding the South .............................................................................. 7 Fig. 4 Time Difference and Longitude......................................................... 8 Fig. 5 Map of the Coast of France ............................................................... 10 Fig. 6 Paris Observatory .............................................................................. 13 Fig. 7 Measuring the Baseline ..................................................................... 15 Fig. 8 Triangulation from Mountain Stations .............................................. 16 Fig. 9 The Southern End of the Meridian Baseline ..................................... 18 Fig. 10 The Northern End of the Meridian Baseline ..................................... 20 Fig. 11 Observing Stars to Find Latitude and Longitude .............................. 22 Fig. 12 Jean Dominique Cassini .................................................................... 24 Fig. 13 Philippe de la Hire ............................................................................. 30 Fig. 14 The Triangulation of Paris Medi ................................................................ 34 Fig. 15 Shadow of the Earth .......................................................................... 40 Fig. 16 Ships Disappearing over the Horizon. ............................................... 40 Fig. 17 Isaac Newton ..................................................................................... 44 Fig. 18 Newton’s Explanation of the Shape of Earth .................................... 46 Fig. 19 Scale of a Degree -Oblate Planet ....................................................... 47 Fig. 20 Scale of a Degree -Prolate Planet ...................................................... 47 Fig. 21 Pierre Maupertuis .............................................................................. 54 Fig. 22 Portable Quadrant of 1730 ................................................................ 58 Fig. 23 Maupertuis on a Sledge in Lapland ................................................... 61 Fig. 24 Charles-Marie La Condamine ........................................................... 66 Fig. 25 Louis Godin ....................................................................................... 67 Fig. 26 César-François Cassini de Thury ....................................................... 74 Fig. 27 Le Monnier’s Meridian ...................................................................... 80 Fig. 28 The Gnomon in St. Sulpice ............................................................... 82 Fig. 29 Mars Climate Orbiter ......................................................................... 89 Fig. 30 Borda Repeating Circle ..................................................................... 91 Fig. 31 Jean-Baptiste-Joseph Delambre......................................................... 96 Fig. 32 Pierre Méchain .................................................................................. 97 Fig. 33 François Arago .................................................................................. 112 ix x List of Figures Fig. 34 Royal Observatory at Greenwich ...................................................... 130 Fig. 35 Jules Janssen ...................................................................................... 137 Fig. 36 John Couch ........................................................................................ 138 Fig. 37 Navigational Satellite System ............................................................ 145 Fig. 38 An Arago Disk .................................................................................. 152 Fig. 39 An Arago Disk in a Typical Parisian Location ................................. 154 Introduction In the spring of 1962 I was studying mathematics and physics at university in England and looking out for something to do in the summer. A notice appeared in the porter’s lodge inviting applications to spend eight weeks at the Royal Greenwich Observatory (RGO) on an astronomy course. In the mornings there would be lectures on all the facets of astronomy carried out at the RGO, in the afternoons students would work on a research topic as assistants to the scientists there. The course was residential and students would stay in Herstmonceux Castle in Sussex, where the RGO was based. We would be offered the accommodation and paid a small allowance as well. I had been an amateur astronomer while at school so I would be paid for doing something I liked. This all sounded great! I applied, and was accepted on to the course. I very much enjoyed this first experience of professional astronomy. My own research topic was to measure the positions and sizes of the spots that represented stars in some photographs of the globular cluster Omega Centauri. I combined my measurements with those that other people had measured on other photographs. I was able to see how the stars moved over time. I could distinguish stars in the cluster from stars in the line of sight in front of and behind the cluster. I could find stars whose brightness changed from photograph to photograph and even discover how some changed rhythmically like a regular heartbeat. I learned how to connect these measurements with the distance of the cluster and to determine its orbit in our Galaxy. It was mindblowing that so much could be learnt from pictures of spots. It was this experience that made me determined to be a professional astronomer. At the end of the course
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