| PLATE | Tofacepage |
| I. | The40?inchRefractoroftheYerkesObservatory | Frontispiece |
| II. | Six-inch Photo-Visual Refractor, equatorially mounted | 31 |
| III. | Twenty-inch Reflector, Stanmore Observatory | 36 |
| IV. | Telescope House and 8½-inch 'With' Reflector | 38 |
| V. | TheSun,February3,1905.RoyalObservatory,Greenwich | 49 |
| VI. | Photograph of Bridged Sunspot (Janssen). Knowledge, February, 1890 | 50 |
| VII. | Solar Surface with FaculÆ. Yerkes Observatory | 60 |
| VIII. | Coronal Streamers: Eclipse of 1898. From Photographs by Mrs. Maunder | 71 |
| IX. | The Chromosphere and Prominences, April 11, 1894.
Photographed by M. H. Deslandres | 74 |
| X. | Venus. H. MacEwen. Five-inch Refractor | 94 |
| XI. | The Moon, April 5, 1900. Paris Observatory | 102 |
| XII. | The Moon, November 13, 1902. Paris Observatory | 108 |
| XIII. | The Moon, September 12, 1903. Paris Observatory | 110 |
| XIV. | Region of Maginus: Overlapping Craters. Paris Observatory | 112 |
| XV. | Clavius, Tycho, and Mare Nubium. Yerkes Observatory | 114 |
| XVI. | Region of Theophilus and Altai Mountains. Yerkes Observatory | 117 |
| XVII. | Apennines, Alps, and Caucasus. Paris Observatory | 119 |
| XVIII. | Chart of the Moon. Nasmyth and Carpenter | 125 |
| XIX. | Key to Chart of Moon. Nasmyth and Carpenter | 125 |
| XX. | Mars: Drawing 1, January 30, 1899—12 hours. Drawing 2, April 22, 1903—10 hours | 135 |
| XXI. | Chart of Mars. Memoirs of the British Astronomical Association, Vol. XI., Part III., Plate VI. | 139 |
| XXII. | Jupiter, January 6, 1906—8 hours 20 minutes. Instrument, 9¼-inch Reflector | 159 |
| XXIII. | Jupiter, February 17, 1906. J. Baikie, 18-inch Reflector | 167 |
| XXIV. | Saturn, July 2, 1894. E. E. Barnard, 36-inch Equatorial | 172 |
| XXV. | Great Comet. Photographed May 5, 1901, with the 13-inch Astrographic Refractor of the Royal Observatory, Cape of Good Hope | 211 |
| XXVI. | Photographs of Swift's Comet. By Professor E. E. Barnard | 220 |
| XXVII. | Region of the Milky Way in Sagittarius, showing a Double Black Aperture. Photographed by Professor E. E. Barnard | 233 |
| XXVIII. | Irregular Star Clusters. Photographed by E. E. Barnard | 256 |
| XXIX. | Cluster M. 13 Herculis. Photographed by Mr. W. E. Wilson | 259 |
| XXX. | Photograph of the Orion Nebula (W. H. Pickering) | 263 |
| XXXI. | Photographs of Spiral NebulÆ. By Dr. Max Wolf | 265 |
| XXXII. | Photograph of Whirlpool Nebula (M. 51). Taken by Mr. W. E. Wilson, March 6, 1897 | 265 |
