OF THE SURFACE OF THE MOON. 
341 
the great ring in all the S.W., S., and S.E. portions are broken ridges, not terrace edges, 
separated by considerable depths from the great encircling crest. Toward the northern 
part there seems a sort of confluence of small ridges from the interior, directed tow r ard 
the spoon-shaped crater, marked A on Madler’s map. The mouldings of the surface of 
this very deep crater are best seen when the moon is a day older. 
Directing our attention to the central mountain-mass, we perceive it to be divided 
into many digitated parts, each diversified by lights and shades, so as to resemble, more 
than anything which I remember, dolomitic or trachytic mountains. On their several 
peaks I have sought carefully for the concavities which might indicate former eruptions, 
but only on one of them, a little removed from the rest, do I feel sure of this occurrence. 
Through these central mountains can be drawn a crescent concave to the S.E., and 
along it occur four small craters, three of them rising separately in the area, and the one 
already mentioned near to the eastern slope of the central mountain. 
The ring of Gassendi, everywhere rugged and fissured, is broken through in one place 
completely, in another less distinctly, both in the south part of the contour, so as to open 
the area to Mare Humorum. In several other places it sinks between points greatly 
elevated. The highest point is on the east border (9000 feet according to Madler), 
where a sort of lacuna, rather than crater, occurs in the middle of the crest; nearly 
opposite to this ridges detach themselves both outwardly and inwardly from the western 
border. 
The north-eastern edge is cut across by three oblique narrow clefts, and the northern 
border is deflected by the concurrence of the ring of the smaller crater. The country 
round Gassendi is very ridgy and mountainous in the east, where it is pressed up, as it 
were, to the great peak and the lacunal crater. This is not the case on the west, which 
side is much lower. On the south, in Mare Humorum, are many small craters not yet 
mapped. On the north, in the high grounds leading to the old degraded crater of 
Letronne, are a few craters apparently of older date than Gassendi. 
As the daylight advances, and especially at midday, much of what has been described 
disappears from sight ; but Gassendi, in consequence of its ridges usually having some 
shadow toward the south, does not lose distinctness in the same proportion as Ptole- 
mseus and the craters near the centre of the moon. 
When the sun is on the meridian of Gassendi, the peculiarities of its surface in 
reflecting light appear conspicuous. Within the south border is a broad dusky space, 
apparently not much undulated, and resembling the dark parts of the Maria. This space 
sometimes appears interrupted by a cross band of comparative brightness. A darkly 
tinted space can also be seen in the N.E. No luminous rays stream from Gassendi. 
In the afternoon, the appearances described in the morning are discovered, as far as the 
main features are concerned, with shadows in the opposite direction; but the views 
have not appeared to me so interesting, nor is the terrestrial hour (early morning) for 
observation so convenient. 
Theophilus, Cyrillus, and Catharina (Plate XVI.), situated south of the equator from 
