84: SCENERY OF THE HEAVENS. 



indicate great superficial inequalities in these regions, apparently similar to what would 

 Le exhibited by the beds of the terrestrial oceans, if the waters were dissipated. Large 

 spaces of depression would then be laid bare, but of very unequal depth, varying from a 

 few fathoms to several miles. Are, then, the vast lunar cavities intended to cradle a 

 fluid element at some approaching epoch, or have they served that office, and by some 

 physical change been deprived of it ? Have the billows rolled and sported in their depths 

 in by -gone time, or are they to come ? These are queries which observed appearances 

 naturally suggest, but we can grasp no certain conclusions. The aspect of the satellite is 

 however thought to favour the idea that the surface has not yet been water-worn that 

 the present stage of its history is parallel to that of the earth, before the sharp asperities 

 of its upheaved masses had been abraded by aqueous action, and smoothed by the detritus 

 which it deposits. It is a striking peculiarity of these districts that they shine with 

 various hues, from the grey tints of the Oceanus Procellarum to the beautiful green of 

 Mare Tranquillitatis, and the dark tracts of Plato. This diversity of colour proceeds, 

 probably, from some difference of substance ; and to distant observers of our own world 

 its chalk, red-sandstone, and granite formations may be supposed to present a similar 

 diverse aspect, as well as the golden sands of Africa in contrast with the grey masses 

 of the Alps, the white cliffs of England, and the green prairies of America. 



The lunar mountains include several chains, the principal of which bears the name of 

 the Apennines, a range running from north-east to south-west, in a straight line towards 

 the centre of the disk, rising to the height of 20,000 feet. This altitude closely approaches 

 that of the loftiest terrestrial mountains, though the diameter of the moon is little more 

 than one-fourth of that of the earth. The chain may be seen casting long shadows over 

 the Mare Imbrium, of which it forms the northern boundary, and from which the ascent is 

 precipitous, while more gradual on the opposite side. Not only are the mountains higher, 

 in proportion to the size of the moon, than those of the earth, but they are larger, much 

 more numerous, and apparently of harder texture, projecting such sharp outlines, and over 

 hanging in such a tremendous manner, as to lead many to the supposition, that the rocks 

 composing them must be of a more solid nature than wrought iron. 



But chains of mountains are exceptions in the lunar world. The prevailing arrangement 

 is circular or craterifonn, though without analogy, when closely examined, to the volcanic 

 formations of our globe. The distinguishing circumstance is, that the areas enclosed are 

 in almost every case depressed far below the general surface of the moon. These hollows 

 in the lunar substance are surrounded with lofty ramparts, which often rise up with the 

 steepness of vertical walls, and have of course their exterior height exceeded by that of the 

 interior. They vary in magnitude from a diameter of not many yards to sixty and even 

 more than a hundred miles; and are termed holes, bulwark-plains, and ring-mountains, 

 according to their size. The floors of these enclosed hollows are in some rare cases flat 

 spaces, strewed with blocks ; in a few instances they appear to be convex ; but very 

 frequently, one or more isolated peaks rise up from them, of a conical or sugar-loaf form, 

 characterised with great abruptness and considerable elevation. When there is a central 

 mountain of this kind in a large enclosure, its shadow is distinctly cast upon the floor, by 

 which its shape can be ascertained, and its height measured trigonometrically. Many 

 of the ring-mountains exhibit conspicuously a radiating aspect, streaks of light issuing 

 from them like the rays of a lamp. The appearance is exactly like that exhibited 

 by a piece of plate-glass struck with a stone. These radiations are comparable to the lava 

 streams of our volcanoes in actual eruption, and were fonnerly considered to be such, but 

 are most probably the illuminated summits of elevated ridges. No trace of active volcanic 

 agency has hitherto been discovered in the moon; and the immense dimensions of its 

 crateriform constructions have no analogy to anything on the earth. 



