Physiognomy of the Moori's Surface. 4l 



remarkable forms, which, both by their number and size, and 

 also by the very singular aspect which they present, never fail 

 to produce astonishment in those who examine them with a 

 powerful glass : We allude to the Lunar Craters. Their general 

 type is the following. An elevated circular rampart, which, 

 externally is nearly perpendicular, and internally is concave, 

 surrounds a spheroidal hollow, which is usually below the level 

 of the plane surface in its neighbourhood. Sometimes, in the 

 interior of this hollow, mountains rise up which, notwithstand- 

 ing their escarpment and their very considerable relative eleva- 

 tion, do not at their summits attain the elevation of the ram- 

 part which surrounds them, and have no connection with it. 



But this fundamental character is so variously modified, and 

 these modifications are so differently associated with each other, 

 and with the diverse forms of the mountains and the seas, that 

 our nomenclature appears meagre indeed when compared with 

 the varied richness of nature, although our distance from our 

 satellite prevents us from recognising many other differences.* 

 We can subdivide these forms according to their relative dimen- 

 sions, which reach from a diameter of thirty German miles (of 15 

 to a degree), to the minimum space we can recognise upon the 

 moon with our present instruments, that is about 1500 feet. 



The spaces surrounded by mountains of this kind which have 

 the largest dimensions ( Wallebene) rarely present a simple en- 

 closure, but more frequently a circular congeries of mountains, 

 with projections which are sometimes exceedingly elevated ex- 

 ternally. Their inner surface is sometimes plane, sometimes 

 convex, and most frequently studded with mountains and small 

 chains of hills. Their outline usually deviates from the circular 

 form, and sometimes exhibits something like great gates or 

 lateral openings. It is in the southern portion of the moon that 

 these particular appearances are most frequently seen, and 

 sometimes they appear so closely crowded upon each other that 

 the circular form is forcibly transformed into a polygonal 

 one. 



The annular mountains, properly so called {Ringgehirge) 



• It will be remembered the miles in this article, when not otherwise stated, 

 are German ; a German mile =s about 4.6 English. 



