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 photograph of Sir G. B. Airy; to Mr. J. Nevil Maskelyne, F.R.A.S., for the portrait of Dr. Maskelyne; to Mr. Bowyer, for procuring the portraits of Bliss and Pond; to Messrs. Edney and Lacey, for many photographs of 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_. [Illustration: THE NEW BUILDING. (_From a photograph by Mr. Lacey._)] CONTENTS CHAPTER PAGE I. INTRODUCTION 13 II. FLAMSTEED 25 III. HALLEY AND HIS SUCCESSORS 60 IV. AIRY 102 V. THE OBSERVATORY BUILDINGS 124 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 XI. THE SPECTROSCOPIC DEPARTMENT 266 XII. THE ASTROGRAPHIC DEPARTMENT 284 XIII. THE DOUBLE-STAR DEPARTMENT 303 INDEX 317 LIST OF ILLUSTRATIONS PAGE FLAMSTEED, THE FIRST ASTRONOMER ROYAL _Frontispiece_ THE NEW BUILDING 7 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 110 THE SOUTH-EAST TOWER 115