CATALOGUE OF LUNAR FORMATIONS FIRST QUADRANT-- West Longitude 90 deg. to 60 deg. West Longitude 60 deg. to 40 deg. West Longitude 40 deg. to 20 deg. West Longitude 20 deg. to 0 deg. SECOND QUADRANT-- East Longitude 0 deg. to 20 deg. East Longitude 20 deg. to 40 deg. East Longitude 40 deg. to 60 deg. East Longitude 60 deg. to 90 deg. THIRD QUADRANT-- East Longitude 0 deg. to 20 deg. East Longitude 20 deg. to 40 deg. East Longitude 40 deg. to 60 deg. East Longitude 60 deg. to 90 deg. FOURTH QUADRANT-- West Longitude 90 deg. to 60 deg. West Longitude 60 deg. to 40 deg. West Longitude 40 deg. to 20 deg. West Longitude 20 deg. to 0 deg. MAP OF THE MOON First Quadrant Second Quadrant Third Quadrant Fourth Quadrant APPENDIX Description of Map List of the Maria, or Grey Plains, termed "Seas," &c. List of some of the most Prominent Mountain Ranges, Promontories, Isolated Mountains, and Remarkable Hills List of the Principal Ray-Systems, Light-Surrounded Craters, and Light Spots Position of the Lunar Terminator Lunar Elements Alphabetical List of Formations INTRODUCTION We know, both by tradition and published records, that from the earliest times the faint grey and light spots which diversify the face of our satellite excited the wonder and stimulated the curiosity of mankind, giving rise to suppositions more or less crude and erroneous as to their actual nature and significance. It is true that Anaxagoras, five centuries before our era, and probably other philosophers preceding him, --certainly Plutarch at a much later date--taught that these delicate markings and differences of tint, obvious to every one with normal vision, point to the existence of hills and valleys on her surface; the latter maintaining that the irregularities of outline presented by the "terminator," or line of demarcation between the illumined and unillumined portion of her spherical superficies, are due to mountains and their shadows; but more than fifteen centuries elapsed before the truth of this sagacious conjecture was unquestionably demonstrated. Selenography, as a branch of observational astronomy, dates from the spring of 1609, when Galileo directed his "optic tube" to the moon, and in the following year, in the _Sidereus Nuncius_, or "the Intelligencer of the Stars," gave to an astonished and incredulous world an account of the unsuspected marvels it revealed. In this remarkable little book we have the first attempt to represent the telescopic aspect of the moon's visible surface in the five rude woodcuts representing the curious features he perceived thereon, whose form and arrangement, he tells us, reminded him of the "ocelli" on the feathers of a peacock's tail,--a quaint but not altogether inappropriate simile to describe the appearance of groups of the larger ring-mountains partially illuminated by the sun, when seen in a small telescope.