Captain tlozet on the Surface of the Moon. 129 



ral of them have a peak in the centre, which is a little less 

 elevated than the edges of the ring. 



The large grey spots cover a great portion of the northern, 

 eastern, and western regions of the disc, and leave in its south- 

 ern part a brilliant space, covered with an infinity of rings 

 of all dimensions. These rings are simple and isolated, com- 

 plex, or united together, two and two, three and three, &c. 

 When they touch one another, the contours are always ren- 

 dered imperfect ; and it is generally the smaller one which 

 encroaches on the larger. In the interior of the large rings 

 there are almost always present smaller ones, which cut the 

 edges when they touch them. The bottom of the rings seems 

 to be flat, but that bottom often presents elevated portions, 

 arranged in arcs of circles parallel to the external ridge ; so 

 that the rings would seem to have been formed at the surface 

 of a fluid mass on which scoriae were floating, by means of a 

 circular undulation, whose amplitude went on diminishing. 



The bottom of the great spots, such as the mare serenitatis, 

 &c., exhibits the same characters. Simple spots are also to 

 be noticed, or portions having no projection, but whose cir- 

 cular forms are well marked. It cannot, therefore, be called 

 in question, that a general cause, producing these circular 

 forms, has had an immense influence in the formation of the 

 solid crust of our satellite. We can perfectly account for all 

 the facts now enumerated, by supposing a number of whirl- 

 pools in the fluid matter, whose amplitude diminished with the 

 fluidity of that matter. Nothing is to be seen on the surface 

 of the moon which reminds us of our chains of mountains 

 with their lateral branches, or of our great valleys with their 

 numerous ramifications, &c. We see^ indeed, many well 

 marked fissures, as, for example, at the bottom of the mare 

 vaporum ; but these fissures are simple ; several diverge from 

 one centre, as in Tycho, Copernicus, Kepler, &c., and form ra- 

 diating cracks, analogous to those in Von Buch's craters o£ 

 soulevement, but much more considerable. One of the fis- 

 sures of Tycho traverses the moon diametrically. A conti- 

 nued study of the various portions of the moon, under all in- 

 clinations of the solar rays, enables us to recognise two layers 

 which are quite distinct, but two layers only ; — the bottom of 



VOL. XLI. NO. LXXXI.c— JULY 1846. I 



