The Lunar Eratosthenes and Copernicus. 279 



focus of the mighty force, which ultimately burst, at this spot, 

 out beneath the open sky. We may observe, too, that this 

 probably shows the condition of the surface at that time, 

 neither so hard as to be inflexible under pressure from beneath, 

 nor so plastic as to return to its original level when the erup- 

 tion came to an end; or, perhaps, that the latter action 

 continued so long that the upheaved area stiffened by degrees 

 into its present form. The exterior height of the wall can 

 hardly be measured with any certainty, the end of the shadow 

 falling on this gradual and very irregular slope ; Schmidt gives 

 it, however, on E. about 4800ft. The central hills, it will be 

 observed, lie far below the exterior surface ; a fact the general 

 prevalence of which upon the Moon had been already noticed 

 by Madler. A great part of this surrounding area was found 

 by Schr. to be covered with an innumerable multitude of greyish 

 ridges, especially S. and S.E., there being fewer 1ST. and E., and 

 scarcely any W. (a fact, we may observe, possibly connected 

 with the greater height of the ring on that side, and if so, 

 showing their posterior formation). These exhibited to him, 

 though not as distinctly as the streams around Aristillus for- 

 merly described, a radiation from the centre. A portion of 

 them has been represented by Herschel, and described as 

 " evident indications of lava-currents streaming outwards in 

 all directions." To travellers from among ourselves, what 

 could be more marvellous than the gradual ascent for some 

 twenty miles among these colossal remains of the ancient fires, 

 while every position of vantage showed us far ahead the abrupt 

 and irregular edge of the crater towering up through many 

 points of the horizon, and assuming as we neared it the most 

 imposing dimensions ; this once reached and climbed — a matter 

 no doubt of severe and continued toil — what a display of crea- 

 tive power would burst upon the view ; terrace beyond terrace 

 beneath our feet, sloping rapidly down to an enormous amphi- 

 theatre as deep, perhaps, as the peak of Mont Blanc is 

 raised above the valley of Ohamouni, and encompassed by a 

 circular cliff, the prolongation of our own standing-ground, 

 the opposite side of which would be as distant from, our eye as 

 Oxford is from London ! But to realize the process by which 

 that gigantic caldron was formed, and the scene which it pre- 

 sented when it was in full action, whatever the nature of that 

 action may have been, surpasses the liveliest human imagi- 

 nation. When at length we could withdraw our eyes from the 

 gulf beneath us, filled perhaps in part with the blackest shade, 

 and could survey the neighbourhood around us, we should find 

 that it comprised much that elsewhere would be deemed of 

 a highly remarkable character ; from the rapid rounding off of 

 the lunar globe, the horizon becomes much more contracted 



