216 Gruithuisen's City in the Moon. 



Biccioli, it should be observed, lies further E., but its name 

 was transferred to this spot by B. and M., in despair of its 

 identification. This, no doubt, may have been impracticable, 

 so far as it depended upon the relief of the surface, and an 

 apology is thus obtained in this case for a change, generally 

 speaking to be avoided ; but the original Rliceticus, which has 

 only recently been recovered by Knott, is a grey opening 

 among the luminous rays issuing from the S."W. side of 

 Copernicus (30), and consequently only to be recognized, where 

 B. and M., no doubt, did not think of looking for it, under 

 high illumination. Three contiguous dark spaces of a circular 

 form were figured here by Hevel, and denominated Lacus 

 Herculei : from Biccioli they received the separate names of 

 Rhceticus, Stadius, and Dominions Maria, occupying respec- 

 tively the E., S.W., and N.W. angles of the triangular area in 

 which they are grouped. They are not difficult objects in the 

 Full Moon, Rhceticus, in particular, which is the darkest, and 

 is divided centrally by a more luminous ray; yet still they are 

 now, especially the other two, so unimportant in character, 

 being merely duller patches in a labyrinth of bright streaks, 

 and so much less conspicuous than very many other anonymous 

 objects, that a suspicion may reasonably arise, whether they 

 were not, at the date of those early observations, of a more 

 decidedly contrasted grey hue than at present. Should there 

 be anything in this, it would of course involve a consequence 

 of some interest — that the streak-system of Copernicus is, in 

 this place at least, on the increase ; and when we bear in mind 

 the very small amount of our actual knowledge as to the local 

 colouring of the Moon, we shall feel that attention may be 

 suitably directed to this spot, where identification and com- 

 parison are proportionally easy. Instances may be given in 

 which variations of brightness in high illumination are probable 

 — Linne, and a bright spot in Werner, may be specified ; and 

 it is time that observers should take this curious point in hand. 

 On the earth, analogous changes, no doubt, may be perceived, 

 but they would result from that cultivation of which we have 

 no suspicion in our satellite. 



It is in this ancient Rhceticus that we are to look for one of 

 the curious " rampart- works" discovered by Gruithuisen. His 

 sketch, in the " Astronomisches Jahrbuch" for 1828, represents 

 a comparatively regular white figure in a longish grey area, 

 consisting of one vertical stripe, bent to the left at the top, 

 where it terminates in a small hill casting a shadow ; ending in 

 something like a little crater, with internal and external shade, 

 at the bottom ; and crossed at an angle of about 00° by four 

 similar bright streaks : the figure might have been worth 

 copying, but that he complains, in the next volume, of its 



