22(> Notices respecting New Books. 



In the third chapter the author divides the entire surface of the 

 moon into three groat classes — namely plains, craters, and moun- 

 tains, the former consisting of the dark and light plains. The well- 

 known formations, "craters," he divides into niue classes — namely 

 walled plains, mountain rings, ring plains, crater plains, craters, 

 craterlets, crater pits, crater cones, and depressions; while he reckons 

 as many as twelve classes of mountains — namely the great ranges, 

 highlands, mountains, and peaks, constituting the greater elevations, 

 while the hill-lands, plateaus, hills, and mountain-ridges form the 

 lesser ; he also particularizes hillocks, mounds, ridges, and land- 

 swells as comprising the smaller irregularities of the surface. 

 Although the number of these divisions is somewhat extensive, it 

 will be useful in studying the smaller lunar features, especially 

 such as occur on the walls of the larger plains. Portions of these 

 walls Mr. Neison is disposed to regard as forming parts of long 

 continuous mountain -ranges — a view, if we mistake not, which has 

 been previously promulgated — many of the walled and ring-plains 

 " appearing," he says, " more like confluent plains or spaces en- 

 closed by intersecting mountain-chains." The most interesting 

 objects in the author's classification of craters are " crater-cones," 

 of which he says : — " Perhaps the true representatives upon the 

 moon of the existing terrestrial volcanoes have only of late years 

 had their distinctive features recognized, and even when excep- 

 tionally well placed are only with difficulty distinguishable from 

 the bright mountain- peaks and minute white spots dispersed over 

 the lunar surface. Steep conical hills or mountain-peaks, from 

 one half to two or three miles in diameter, with deep cone-like 

 central depressions scarcely one half of this size in diameter, they 

 remain in high illumination, visible as white brilliant spots of 

 minute dimensions, and only under favourable conditions can their 

 central apertures be detected even in the most powerful instru- 

 ments. . . . Under any circumstances they are difficult to 

 distinguish from bright mountain-peaks and white spots, whilst in 

 many ways they bear a considerable resemblance to terrestrial 

 volcanic cones ; and it is therefore not without interest to find that 

 many phenomena perhaps indicating actual lunar changes present 

 themselves in observing these objects." In this chapter the author 

 draws attention to those remarkable features known as rills or 

 clefts, and the great ray-systems, also to the different varieties of 

 brightness and colour found on the surface of our satellite. 



Chapter IV. is devoted to general lunar history ; we, however, 1 

 think that, had the author given separately the two branches of 

 history, viz. that which culminated in the advanced state of the 

 lunar theory and that which has reference to the surface, both (as 

 at present) arranged chronologically, some little trouble to the 

 selenographer would have been saved. 



The last chapter, V., of those forming the Introduction treats of 

 the variations of the surface ; and of these the author has taken, as 

 it appears to us, the most consistent and truthful views, considering 

 that so little is really known of the vast majority of the minor 

 details of the moon's surface. He says that "a very considerable 

 alteration of the present constitution of the surface might occur at 



