COPERNICUS. 147. This may deservedly be considered one of the grandest and most instructive of lunar craters. Though its diameter (46 miles) is exceeded by that of other craters, its situation near the center of the lunar disc renders it so conspicuous as to make it a favorite object for observation. Its vast rampart rises to upwards of 12,000 feet above the level of the plateau, nearly in the center of which stands a magnificent group of cones attaining the height of upwards of 2400 feet. The rampart is divided by concentric segmented terraced ridges, which present every appearance of being enormous landslips, resulting from the crushing of their overloaded summits which have slid down in vast segments and scattered their debris on the plateau. Corresponding vacancies in the rampart may be observed from whence these prodigious masses have broken away. The same may be noticed, to a somewhat modified degree, around the exterior of the rampart. For upwards of 70 miles around Copernicus myriads of comparatively minute but perfectly formed craters can be seen. The district on the southeast side is especially rich in them. Many somewhat radial ridges or spurs may be observed leading away from the exterior banks of the great rampart. They appear to be due to the freer egress which the extruded matter found near the focus of disruption. TRIESNECKER. 150. A fine example of a normal lunar volcanic crater having all the usual characteristic features in great perfection. Its diameter is about 20 miles and it possesses a good example of the central cone and also of interior terracing. The most notable feature, however, is the remarkable display of cracks or chasms which may be seen to the west side of it. Several of these cracks obviously diverge from near the west external bank of the great crater and they sub-divide or branch out as they extend from the apparent point of divergence, while they are crossed or intersected by others. These cracks or chasms are nearly one mile wide at their widest part and after extending for fully 100 miles taper away till they become invisible.