_Archimedes._ One of the most definite and regular of the walled plains. It is 60 miles in diameter, with a wall rising about 4200 feet above the surface. Some small craters and various streaks diversify its centre.
_Tycho._ A grand ring-plain, 54 miles in diameter and about 17,000 feet (= nearly 3 miles) deep, and forming the centre of the chief ray-system of the Moon. The light-radiations stretch over one fourth of the visible hemisphere at the full, but they are imperceptible with the Sun’s altitude below 20°. These remarkable radiations from Tycho form a striking aspect of lunar scenery, and any small telescope reveals them. Webb has termed Tycho “the metropolitan formation of the Moon;” and the idea embodied in the expression must strike observers as very apposite. This object is visible to the naked eye at the time of full. A fine hill rises from its centre to a height of 5500 feet.
_Copernicus._ A magnificent ring-plain, 56 miles in diameter, and surrounded by a wall (in which there are terraces and lofty peaks, separated by ravines) attaining an elevation of 11,000 feet. There is a central hill of nearly 2500 feet. From Copernicus light-streaks are plentifully extended on all sides, and apparently connect this object with the many others of similar character which are situated in this region. Neison says that near Copernicus the light-streaks unite and form a kind of nimbus or light-cloud about it. The streaks are most conspicuous towards the N., where they are from 5 to 14 miles in width. To the N.W. of Copernicus, about halfway in the direction of the neighbouring ring-plain _Eratosthenes_ (and N. of Stadius), there is a considerable number of crater-pits. Mädler figured sixty-one of these, and regarded that number as certainly less than half the total number visible. They appear to be ranged in rows or streams, and are so close together in places as to nearly form crater-rills. Schmidt saw the ground hereabout pierced like a honeycomb, and managed to count about 300 little craters; but they are so thickly strewn in this district that exact numbers or places cannot be assigned. They are best observable when the Sun is rising on the E. wall of Copernicus. The interior of this fine object shows six or seven peaks, which are often capped with sunshine, and very brilliant amid the black shadow thrown from the surrounding wall.