Gruithuisen's City in the Moon. 221 



given by Gr., they concluded that his fortification was to be 

 looked for; and this time, by means of the great Berlin achro- 

 matic of 9^-0- in. aperture, they were successful. Two principal 

 directions of the long ridges abounding in the district were 

 very evident, one in the meridian, another intersecting it from 

 N.E. in an angle of 50°. In the first direction are two low, 

 but partially steep chains, bearing several insulated summits, 

 which connect (a) and Y at their ends ; to the second belong, 

 among others, 4 cross banks which connect these two chains 

 by oblique lines, so as to enclose 5 longish valleys in succession, 

 each about 9m. long by 3^- wide. The uniform height of the 

 side and cross walls, and the similarity in form and size of 

 these hollows give an aspect of regularity to this figure, which 

 is increased when they are filled with shadow, and the dividing 

 ridges appear as bright, straight, narrow lines. It is, however, 

 evident that we have only a product of nature in view. Many 

 equally regular arrangements are to be found in the Moon, of 

 which a remarkable instance has already been described in the 

 environs of Aristoteles, and the magnitude of any one of these 

 valleys is sufficient to include the greatest cities of the earth. 

 (London, however, should have been excepted.) They further 

 remark that a 3rd meridian chain (on E.) unites itself with the 

 second (or central one), before it reaches T, and forms a valley 

 with it, less precipitous than the others. Their diagram shows 

 it also connecting itself with the central chain near its middle; 

 and gives two strong prolongations, each composed of more 

 than one ridge, of the oblique walls towards S.W. Thus the 

 main features of the figure are well made out ; the observers 

 however have not stated, what must undoubtedly have been 

 the case, that their own smaller instrument would have fully 

 sufficed for the recovery of the object in a suitable position. 

 It only remains for us to remark what has been seen in our own 

 country. 



The earliest verification, so far as I know, was effected by 

 Knott, 1861, Mar. 19, when the details of B. and M. were very 

 fairly caught with a 7^-in. object-glass ; and they were sub- 

 sequently made out even at some distance from the terminator. — 

 1862, Feb. 7, I had a good view of it with my 5|-in. object- 

 glass, with a power of 170, definition being flaring and un- 

 pleasant, but not bad. It was not very close to the terminator, 

 which was then bisecting Timocharis (34), and grazing the 

 E. edge of Eratosthenes (29). The central ridge connecting T 

 and (a) was very apparent. E. of it I could distinguish little, 

 but on the W. I was able to reckon 4 oblique walls, the first 

 starting from Y, to which a 5th very short one might be added 

 close to (a), if I was correct in thinking that the central ridge 

 branched out right and left at its N. end, instead of running 



