xiSS* i&S* cO^' <py" cjs- D/^ (&?* oiV* T v. v. > v JHDER-f^a-s {^m b#tt+j+jiLe.. ASTRONOMY LIBRARY WELLESLEY COLLEGE LIBRARY PRESENTED Br ^SOScj Wise fearing leajtefh to hlqkev levels. ana to farmer shores -w^vcwwv OC^^U- trfrJLtst** - ^JfU^CL^^y y i^rt>^- V FLAMSTEED, THE FIRST ASTRONOMER ROYAL. {From the portrait in the ' Historia Ccelestis .') THE ROYAL OBSERVATORY GREENWICH A GLANCE AT ITS HISTORY AND WORK EY E. WALTER MAUNDER, F.R.A.S. WITH MANY PORTRAITS AXD ILLUSTRATIONS FROM OLD PRINTS AND ORIGINAL PHOTOGRAPHS LONDON THE RELIGIOUS TRACT SOCIETY 56 Paternoster Row, and 65 St. Paul's Churchyard 1900 i*\So t> LONDON" : PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, STAMFORD STREET AND CHARING CROSS. ^HA 92 PREFACE I WAS present on one occasion at a popular lecture delivered in Greenwich, when the lecturer referred to the way in which so many English people travel to the ends of the earth in order to see interesting or wonderful places, and yet entirely neglect places of at least equal importance in their own land. 1 Ten minutes' walk from this hall,' he said, ' is Greenwich Observatory, the most famous observatory in the world. Most of you see it every day of your lives, and yet I dare say that not one in a hundred of you has ever been inside.' Whether the lecturer was justified in the general scope of his stricture or not, the particular instance he selected was certainly unfortunate. It was not the fault of the majority of his audience that they had not entered Greenwich Observatory, since the regulations by which it is governed forbade them doing so. These rules are none too stringent, for the efficiency of the institution would certainly suffer ' if it were made a show ' place, like a picture 5 6 PREFACE gallery or museum. The work carried on therein is too continuous and important to allow of inter- ruption by daily streams of sightseers. To those who may at some time or other visit the Observatory it may be of interest to have at hand a short account of its history, principal instru- ments, and work. To the far greater number who will never be able to enter it, but who yet feel an interest in it, I would trust that this little book may prove some sort of a substitute for a personal visit. I would wish to take this opportunity of thanking the Astronomer Royal for his kind permission to reproduce some of the astronomical photographs taken at the Observatory and to photograph the domes and instruments. I would also express my thanks to Miss Airy, for permission to reproduce the of Sir photograph G. B. Airy ; to Mr. J. Nevil Maskelyne, F.R.A.S., for the portrait of Dr. Maske- lyne ; to Mr. Bowyer, for procuring the portraits of Bliss and Pond ; to Messrs. Edney and Lacey, for many of photographs the Royal Observatory ; and to the Editor of Engineering, for permission to copy two engravings of the Astrographic telescope. E. W. M. Royal Observatory, Greenwich, August^ 1900. ) THE NEW BUILDING. {From a photograph by Mr. Lacey. CONTENTS CHAPTER PAGE I. Introduction . 13 rfc Flamsteed 25 III. Halley and his Successors 60 IV. Airy .... 102 V. The Observatory Buildings 124 7 8 CONTENTS CHAPTER PAGE VI. The Time Department 146 VII. The Transit and Circle Departments . 181 VIII. The Altazimuth Department .... 205 IX. The Magnetic and Meteorological Departments 228 X. The Heliographic Department . .251 XL The Spectroscopic Department .... 266 XII. The Astrographic Department .... 284 - XIII. The Double-Star Department . 303 Index 317 LIST OF ILLUSTRATIONS Flamsteed, the First Astronomer Royal . Frontispiece The New Building General View of the Observatory Buildings from the New Dome 12 Flamsteed's Sextant 36 The Royal Observatory in Flamsteed's Time 44 The 'Camera Stellata' in Flamsteed's Time 52 Edmund Halley 61 Halley's Quadrant . 69 James Bradley . 72 Graham's Zenith Sector 77 Nathaniel Bliss 83 Nevil Maskelyne 87 Hadley's Quadrant . 91 John Pond 96 George Biddell Airy, Astronomer Royal 103 The Astronomer Royal's Room 1 10 The South-east Tower .... "5 121 W. H. M. Christie, Astronomer Royal . The Astronomer Royal's House 127 The Courtyard 130 i34 Plan of Observatory at Present Time . i47 The Great Clock and Porter's Lodge . The Chronograph 158 The Time-desk ...... 164 Harrison's Chronometer .... 165 9 IO LIST OF ILLUSTRATIONS PAGE The Chronometer Room . 167 The Chronometer Oven . 171 The Transit Pavilion 174 ' ' Lost in the Birkenhead 179 The Transit Circle I89 The Mural Circle . 195 Airy's Altazimuth . 208 New Altazimuth Building 211 The New Altazimuth 213 The New Observatory as seen from Flamsteed' Obser vatory ...... 219 The Self-registering Thermometers 235 The Anemometer Room, North-west Turret 24O The Anemometer Trace .... 243 Magnetic Pavilion—Exterior . 246 — Magnetic Pavilion Interior . 248 The Dallmeyer Photo-heliograph . 254 Photograph of a Group of Sun-spots . 259 The Great Nebula in Orion . 269 The Half-prism Spectroscope on the South-east Equa torial .... 273 The Workshop . 276 The 30-iNCH Reflector with the New Spectroscope attached .... 278 ' Chart Plate ' of the Pleiades 286 The Control Pendulum and the Base of the Thompson Telescope ........ 289 The Astrographic Telescope ..... 29I The Driving Clock of the Astrographic Telescope 294 The Thompson Telescope in the New Dome . 297 The Nebula of the Pleiades. .... 3OO Double-star Observation with the South-east Equa torial ........ 308 The South-east Dome with the Shutter Open 314 s So £ ' THE ROYAL OBSERVATORY GREENWICH CHAPTER I INTRODUCTION I HAD parted from a friend one day just as he met an acquaintance of his to whom I was unknown. 'Who is that?' said the newcomer, referring to me. My friend replied that I was an astronomer from Greenwich Observatory. * ? Indeed ; and what does he do there This question completely exhausted my friend's information, for as his tastes did not lead him in the direction of astronomy, he had at no time ever concerned himself to inquire as to the nature of my official duties. ' Oh—er—why—he observes, don't ? you know ' and the answer, vague as it was, completely slaked the inquirer's thirst for knowledge. It is not every one who has such exceedingly nebulous ideas of an astronomer's duties. More frequently we find that the inquirer has already formed a vivid and highly-coloured picture of the astronomer at his 'soul-entrancing work.' Resting *3 i4 THE ROYAL OBSERVATORY on a comfortable couch, fixed at a luxurious angle, the eye-piece of some great and perfect instrument brought most conveniently to his eye, there passes before him, in grand procession, a sight such as the winter nights, when clear and frosty, give to the ordinary gazer, but increased ten thousand times in beauty, brilliance, and wonder by the power of his telescope. For him Jupiter reveals his wind-drifted clouds and sunset colours ; for him Saturn spreads his rings ; for him the snows of Mars fall and melt, and a thousand lunar plains are ramparted with titanic crags ; his are the star-clusters, where suns in their first warm youth swarm thicker than hiving bees ; his the faint veils of nebulous smoke, the first hint of shape in worlds about to be, or, perchance, the last relics of worlds for ever dead. And beside the enjoyment of all this entrancing spectacle of celestial beauty, the fortunate astronomer sits at his telescope and discovers—always he discovers. This, or something like it, is a very popular astronomer's experiences and conception of an duty ; and consequently many, when they are told that ' discoveries ' are not made at Greenwich, are inclined to consider that the Observatory has failed in its ' purpose. An astronomer without discoveries ' to his record is like an angler who casts all day and comes home without fish —obviously an idle or in- competent person. Again, it is considered that astronomy is a most transcendental science. It deals with infinite distances, with numbers beyond all power of human intellect to appreciate, and therefore it is supposed, on the INTRODUCTION 15 one hand, that it is a most elevating study, keeping the mind continually on the stretch of ecstasy, and, on the other hand, that it is utterly removed from all connection with practical, everyday, ordinary life. These ideas as to the Royal Observatory, or ideas like them, are very widely current, and they are, in every respect, exactly and wholly wrong. First of all, Greenwich Observatory was originally founded, and has been maintained to the present day, for a strictly practical purpose. Next, instead of leading a life of dreamy ecstasy or transcendental speculation, the astronomer has, perhaps, more than any man, to give the keenest attention to minute practical details. His life, on the one side, approximates to that of the engineer ; on the other, to that of the accountant. Thirdly, the professional astronomer has hardly any- thing to do with the show places of the sky. It is quite possible that there are many people whose sole opportunity of looking through a telescope is the penny peep through the instrument of some itinerant showman, who may have seen more of these than ' an active astronomer in a lifetime ; while as to dis- coveries,' these lie no more within the scope of our national observatory than do geographical discoveiies within that of the captain and officers of an ocean liner. If it is not to afford the astronomer beautiful spectacles, nor to enable him to make thrilling discoveries, what is the purpose of Greenwich Ob- servatory ? First and foremost, it is to assist navigation.