218 



Gruithuisen' s City in the Moon. 



in fact, lies beyond our proper bounds, to the spot so called by 

 B. and M., with which we complete our survey of the First 

 Quadrant of the Moon. 



"We commence the second, at the centre of the disk, with 

 the Sinus Medii, Gr on our Index-map. This is an undefined 

 tract of level ground, of little comparative importance, except- 

 ing from its lying in the visible centre of the hemisphere. It 

 contains only two small craters, and a few short and low 

 ridges ; bat varied illumination produces much change in its 

 shading. From its position relative to the Sun and Earth, 

 this is the point of the Moon which receives the greatest share 

 of illumination ; here, with the exception of a few polar 

 summits, is the minimum of darkness, and eyes like ours 

 would be able at all times (except during a total eclipse) to 

 read writing of a moderate size. Here, too, the smallest 

 possible margin is left for deception ; the changes of libration 

 and phasis have the least effect upon the prospect ; and it is 

 accordingly especially adapted for the study of those who make 

 the discovery of physical change their object : it is unfortunate, 

 our authors might have added, that the region is little marked 

 by any interesting peculiarity. 



Such, however, is not the case with the district lying F. 

 and N.E. of it, some of the features of which are so curious, 

 that the accompanying diagram is introduced to assist in its 





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identification. The Moon's centre is here indicated by the two 

 crossing lines, of which that from right to left is the equator, 



