Plates I. and II. are views of the Observatory and Instruments recently erected by Mr. Klein at Stanmore, Middlesex, lat. 51° 36′ 57″ N., long. 0° 18′ 22″ W. The height above sea-level is 262 feet. The telescope is a 20-inch reflector by Calver, of 92 inches focus; the tube is, however, 152 inches long so as to cut off all extraneous rays. It is mounted equatoreally, and is provided with a finder of 6 inches aperture—one of Tulley’s famous instruments a century ago. The large telescope is fixed on a pillar of masonry 37 feet high, and weighing 115 tons. Mr. Klein proposes to devote the resources of his establishment to astronomical photography, and it has been provided with all the best appliances for this purpose. The observatory is connected by telephone with Mr. Klein’s private residence, and the timepieces and recording instruments are all electrically connected with a centre of observation in his study. CONTENTS. CHAPTER I. Page THE TELESCOPE, ITS INTENTION AND THE DEVELOPMENT OF ITS POWERS 1 CHAPTER II. RELATIVE MERITS OF LARGE AND SMALL TELESCOPES 20 CHAPTER III. NOTES ON TELESCOPES AND THEIR ACCESSORIES 38 CHAPTER IV. NOTES ON TELESCOPIC WORK 66 CHAPTER V. THE SUN 87 CHAPTER VI. THE MOON 113 CHAPTER VII. MERCURY 137 CHAPTER VIII. VENUS 145 CHAPTER IX. MARS 155 CHAPTER X. THE PLANETOIDS 167 CHAPTER XI. JUPITER 170 CHAPTER XII. SATURN 195 CHAPTER XIII. URANUS AND NEPTUNE 215 CHAPTER XIV. COMETS AND COMET-SEEKING 227 CHAPTER XV. METEORS AND METEORIC OBSERVATIONS 260 CHAPTER XVI. THE STARS 286 CHAPTER XVII. NEBULÆ AND CLUSTERS OF STARS 324 NOTES AND ADDITIONS 347 INDEX 353 ILLUSTRATIONS. PLATE I. Interior of Mr. Klein’s Observatory _Frontispiece_ II. View of Mr. Klein’s Grounds and Observatory _To face_ p. 82 FIG. PAGE