340 J.D. Dana on the Volcanoes of the Moon. 
eular pits. In still others, especially the largest, the enclosing 
walls are broken into a series of ridges, sometimes with large 
openings like the break of an eruption: yet even then the irreg- 
ular forms may generally be referred either to a single circle, to 
a combination of circles, or to the formation of successive ridges 
one within another. .The bottom of the pits though generally 
flat or nearly so, not unfrequently contains small cones, or ridge- 
like elevations; we call them small, though some are 5000 feet 
in height, for they are mere dots in the immense basin. Over 
the exterior slopes there are many lateral cones of the same small 
dimensions, and occasionally one as large as Etna may be distin- 
guished, besides others of different sizes to a few hundred feet in 
breadth. There are also circular craters within the a “ 
which are of various dimensions. 
The pointed cones or peaks, excepting those immediately con- 
nected with the pit-craters, are few in number. According to 
Beer and Midler, Dérfel, the most elevated lunar peak measured, 
is 24,945 feet in height; it is situated in the lunar Aue 
Huygens, another peak, is 18,209 feet in altitude. 
The mountain ridges are peculiar in being generally slongatal 
elevations, or clusters of such elevations, without valleys intersect- 
ing their declivities, and thus very unlike the chains of our globe. 
As M. Rozet and others have remarked, there is no water on the 
moon to wear out valleys. . 
Many of the depressions called seas, of which the Mare Seren- 
itatis, and Mare Crisium, are examples, vary in breadth to five 
or six hundred miles, and notwithstanding their size, they are 
identical in character with the great pit-craters, their extent and 
less depth being their only characteristics. 'This view is suggest 
ed by M. Rozet, and their features clearly sustain it. They con 
tain cones-and circular areas like the better defined pits.* 
The light streaks alluded to form radiating lines around large 
cones, and especially about Euler, Kepler, Copernicus, and Aris- 
tarchus. 'They are from one to five hundred miles in length, 
and cross ridges and depressions, without interruption. They 
coalesce about the summit of Honiet, so that the whole surface 
appears nebulous. 
sit ne er le di inline 
* The ‘‘seas,” according to M. Rozet, ha have escarpments of 45 degrees, some of 
which are 400 metres in height. In the interior there are annular lar eatin pei 
rings in shape, the diameter of which attain to 100,0 
