Historical & Cultural Astronomy Historical & Cultural Astronomy EDITORIAL BOARD JAMES EVANS, University of Puget Sound, USA MILLER GOSS, National Radio Astronomy Observatory, USA JAMES LEQUEUX, Observatoire de Paris, France SIMON MITTON, St. Edmund’s College Cambridge University, UK WAYNE ORCHISTON, National Astronomical Research Institute of Thailand, Thailand MARC ROTHENBERG, AAS Historical Astronomy Division Chair, USA VIRGINIA TRIMBLE, University of California Irvine, USA XIAOCHUN SUN, Institute of History of Natural Science, China GUDRUN WOLFSCHMIDT, Institute for History of Science and Technology, Germany More information about this series at http://www.springer.com/series/15156 Clifford J. Cunningham Editor The Scientific Legacy of William Herschel Editor Clifford J. Cunningham Austin, Texas, USA ISSN 2509-310X ISSN 2509-3118 (electronic) Historical & Cultural Astronomy ISBN 978-3-319-32825-6 ISBN 978-3-319-32826-3 (eBook) https://doi.org/10.1007/978-3-319-32826-3 Library of Congress Control Number: 2017952742 © Springer International Publishing Switzerland 2018 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Cover image: Late 20th century bronze medal commemorating the Herschel family: John (left), William (centre) and Caroline (right). In possession of the author Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer International Publishing AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Foreword Among the great scientists of the past, William Herschel (1738–1822) is excep- tional in that for half his life he was a musician who hoped to be remembered for his symphonies and concertos. He was born in the capital city of the German “elector- ate” of Hanover, of which the elector was also the king of Britain. George II lived in London and administered his electorate from there, but he maintained a small army in Hanover, and Herschel’s father was a humble bandsman in the Hanoverian Guards. On leaving the Garrison School at age fourteen, Herschel joined his father as a boy-bandsman. In 1757, the Hanoverians were defeated in battle by the French, and Herschel (who as a boy was not under oath) deserted and fled to England in company with his older brother Jacob. The boys scratched a living from music in the London area, until in 1759 the French were expelled and Jacob was able to return home. Herschel however was a deserter, and in any case, he preferred life in England. In 1760, find- ing London “overstocked with musicians,” he accepted a part-time post in the north- ern county of Yorkshire, and there he lived the stressful and demanding life of a jobbing musician. Hoping to secure the more stable position of church organist, he began to teach himself the organ, and his dreams came true in 1766 when – probably by recom- mendation of a friend – he was offered the post of organist in the Octagon Chapel building in the fashionable spa resort of Bath in the west of England. Bath was second only to London in the opportunities it offered to enterprising musicians in the season, which lasted from the autumn to Easter. Herschel’s father had encouraged him to be intellectually curious, and it was probably in 1772 that he bought a copy of Opticks by the Cambridge professor Robert Smith. Opticks told the reader a lot about how to construct telescopes and a little of what to see with the finished instrument. It was that autumn that Herschel journeyed to Hanover to rescue his sister Caroline (1750–1848) from servitude to their illiterate mother. The pretext was that she might sing in the oratorios that he mounted from time to time, especially in Holy Week. It is a sign of his newfound interest in astronomy that, on the return journey through London, he took her to visit the shops of opticians. v vi Foreword Caroline accepted that, during the coming season, her brother would be too busy to spare time to coach her singing, but she hoped for better things after Easter. To her dismay, she found that her brother was obsessed with astronomy. In the years to come, she struggled to make a career as a singer, but the odds were stacked against her. Meanwhile, her brother experimented with the construction of reflecting tele- scopes, and in 1778, he made himself a 6-inch mirror for his 7-ft reflector that (though he did not know it) was the finest of its type on the planet. In 1779, he decided to use it systematically to familiarize himself with the brighter stars visible from Bath. And so it was that on 13 March 1781 he came to examine a (supposed) star in Taurus. With his superb mirror, he saw at a glance that it was not a star. Returning to the object 4 days later, he found that it had moved, and so was nearby, a member of the Solar System. Not knowing of speculations about undiscovered planets, he supposed it to be a comet. By now Herschel had made contact with fellow enthusiasts in matters scientific, and he even had links with the Royal Society of London. This remarkable Bath musician-astronomer had acquired a circle of admirers, not least the president of the Royal Society Sir Joseph Banks – men who appreciated his talents and hoped to find some way for him to dedicate himself solely to astronomy. When the supposed comet proved to be a major planet (the one known to us as Uranus), they had their chance. King George III was a cultivated man and an amateur astronomer, and Banks suggested to him that Herschel might be the next astronomer at the king’s observatory at Kew. This position was already promised, but after anxious thought, George decided to make Herschel his private astronomer, required to live near Windsor Castle and be available to the royal family from time to time but otherwise free to dedicate himself to astronomy. In this way, the king rewarded Herschel for naming his planet the Georgium Sidus. Herschel simply took it for granted that his sister would abandon her career as a singer and quit fashionable Bath in order to live as his assistant astronomer in a tiny Berkshire village where nothing ever happened. He was right, and for some years, Caroline lived a busy and fulfilled life as the mistress of the Herschel household, an amanuensis to her brother astronomer, and even an observer in her own right. Some astronomers in history have excelled as instrument-makers, some as observers, and some as theoreticians. Uniquely, Herschel excelled at all three. We have seen how the excellence of his telescope mirror was key to his discovery of a new planet. Months after becoming a professional astronomer, Herschel completed a reflector of 20-ft focal length and with 18-inch mirrors that in his hands (and later, refurbished, in the hands of his son John) became one of the great telescopes of his- tory. The king, no doubt aware that he had driven a hard bargain in terms of salary, encouraged Herschel to supplement his income by making reflectors for sale and placing an order for five of 10-ft focal length. Herschel became the premier European maker of reflectors, and his clients included the King of Spain and the Empress of Russia. For his own use, with royal funding, he made a monster of 40-ft focal length and 4-ft mirrors weighing up to a ton, but this proved a cumbersome failure. As an observer, Herschel had discovered his planet while searching among the brighter stars for those that were double, and this resulted in two long catalogs of Foreword vii doubles. When he became the king’s astronomer, he soon focused on the problem of whether the milky patches known as nebulae were vast star systems disguised by distance or were nearby clouds of luminous fluid. He resolved to search the sky vis- ible from Windsor for specimens of nebulae. In his “sweeps,” he would be at the eyepiece of the 20-ft scanning the sky as it rotated overhead, while Caroline was at a desk at a nearby window ready to copy down his shouted observations. The next day, she would write up a fair copy, and she eventually assembled catalogs for pub- lication that totaled 2500 specimens. Her accuracy almost defies belief, and her role though humble was crucial to the success of the team. The Newtonian universe saw God as the great clockmaker whose mechanism functioned eternally without fundamental change. Herschel by contrast saw in star clusters evidence that gravity (or a similar attractive force) was at work among the stars, and if so, then in time a scattered cluster would mature by becoming more and more condensed.