The illustrations have been mainly chosen with the view of representing to the general reader some of the results of the best modern observers and instruments; but I have ventured to reproduce a few specimens of more commonplace work done with small telescopes. I desire to offer my cordial thanks to those who have so kindly granted me permission to reproduce illustrations from their published works, or have lent photographs or drawings for reproduction--to Miss Agnes Clerke for Plates XXV.-XXVIII. and XXX.-XXXII. inclusive; to Mrs. Maunder for Plate VIII.; to M. Loewy, Director of the Paris Observatory, for Plates XI.-XIV. and Plate XVII.; to Professor E. B. Frost, Director of the Yerkes Observatory, for Plates I., VII., XV., and XVI.; to M. Deslandres, of the Meudon Observatory, for Plate IX., and the gift of several of his own solar memoirs; to the Astronomer Royal for England, Sir W. Mahony Christie, for Plate V.; to Mr. H. MacEwen for the drawings of Venus, Plate X.; to the Rev. T. E. R. Phillips for those of Mars and Jupiter, Plates XX. and XXII.; to Professor Barnard for that of Saturn, Plate XXIV., reproduced by permission from the _Monthly Notices_ of the Royal Astronomical Society; to Mr. W. E. Wilson for Plates XXIX. and XXXII.; to Mr. John Murray for Plates XVIII. and XIX.; to the proprietors of _Knowledge_ for Plate VI.; to Mr. Denning and Messrs. Taylor and Francis for Plate III. and Figs. 6 and 20; to the British Astronomical Association for the chart of Mars, Plate XXI., reproduced from the _Memoirs_; and to Messrs. T. Cooke and Sons for Plate II. For those who wish to see for themselves some of the wonders and beauties of the starry heavens the two Appendices furnish a few specimens chosen from an innumerable company; while readers who have no desire to engage in practical work are invited to skip Chapters I. and II. CONTENTS CHAPTER PAGE I. THE TELESCOPE--HISTORICAL 1 II. THE TELESCOPE--PRACTICAL 14 III. THE SUN 47 IV. THE SUN'S SURROUNDINGS 68 V. MERCURY 81 VI. VENUS 89 VII. THE MOON 100 VIII. MARS 130 IX. THE ASTEROIDS 148 X. JUPITER 154 XI. SATURN 172 XII. URANUS AND NEPTUNE 190 XIII. COMETS AND METEORS 203 XIV. THE STARRY HEAVENS 230