362 SPECIAL RESULTS IN THE URANOLOGICAL 



otherwise directly illuminated by the Sun, the points some- 

 times shine almost like stars. All these alternations of 

 light and shade affect an iodized plate, and, with strong 

 magnifying powers, are represented on Daguerreotypes with 

 admirable fidelity. I possess myself such a light-picture of 

 the Moon, of two inches' diameter, in which the so-called 

 seas and annular mountains are clearly recognised : it was 

 prepared by a distinguished artist, Mr. Whipple, of Boston. 

 If, in some of the " seas" (Crisium, Serenitatis, and Hu- 

 morum) we are struck with the circular form, we find the 

 same repeated still more frequently, and indeed almost uni- 

 versally, on the mountainous part of the Moon's disk, par- 

 ticularly in the configuration of the enormous masses of 

 mountain which fill the southern hemisphere from the pole 

 nearly to the equator, where the mass terminates in a point. 

 Many of the annular mountains and wall-surrounded plains 

 (the largest containing, according to Lohrmann, above a 

 thousand square miles) form connected series running in the 

 direction of meridians, between 5 and 40 South latitude 

 ( 584 ). The northern polar region contains comparatively 

 a very small proportion of these crowded mountain rings ; 

 but between 20 and 50 North latitude, near the western 

 margin of the northern half of the Moon's disk, they form 

 a connected group. The Mare Frigoris approaches to 

 within a few degrees of the North Pole itself ; and thus 

 this part, like the whole of the level north-eastern space, 

 inclosing only a small number of isolated annular 

 mountains, (Plato, Mairan, Aristarchus, Copernicus, and 

 Kepler), presents a great contrast to the more mountainous 

 Southern Pole. Near the latter, lofty summits shine, in the 



