PLATE V. 



Moo7i's age, 21 days 16 liours. 1895, 



In this plate is depicted an area from near the moon's equator to near the south 

 pole. On the eastern margin the sunlight is passing from the surface, the evening 

 light being so oblique that the bottoms of the vulcanoids are more or less in shadow. 

 Here and there, in the advancing night, there are lofty peaks on the margin of crater 

 rims, which still receive a touch of sun and appear as bright points in a black field. 

 On the western margin the surface is still well illuminated, with the consequent 

 effect that the surface appears to be much smoother than it is. A view taken a few 

 hours later would show about as rude a margin as is here depicted. 



Perhaps more effectively than any other this view shows how the general surface 

 of the moon outside of the maria is essentially made up of vulcanoids and ridges, the 

 apparently smooth parts appearing so only because the small irregularities are not 

 visible. In this connection it should be noted that near the dark part the surface 

 is seen to be beset by small shallow craters, the smallest visible being more than a 

 mile in diameter and probably several hundred feet deep. Such pits, in equal num- 

 bers to the unit of surface, exist on the bright part to the left when they are observed 

 by the higher light. 



The way in which the smaller craters cut the larger is shown at many points in 

 this field of view; so, too, the relative lack of sharpness of outline of the greater 

 vulcanoids as compared with the lesser objects of this group. The low, narrow 

 ridges which surround the pits are insufficiently shown because the light does not 

 bring them out. They are best observed near the uppermost part of the picture. 



The generality of the fact that the larger craters have flat floors and that these 

 floors are prevailingly nearly level is well indicated; so, too, the fact that there is 

 a common tendency of these floors to have either a small crater or a cone in or 

 near the center of each circular field. Four such craters in the central part of the 

 area extending in an obscure line from near the base to near the middle of the pic- 

 ture have cones in their centers. In all, about a dozen of the hundred or so instances 

 in which they would be recognizable have this feature. It will be evident that all 

 the craters in this region have their floors far below the level of the encircling ring 

 and below the general lunar surface. 



In sundry instances two adjacent vulcanoids of moderate size have their neighbor- 

 ing walls broken down so that they exhibit the first stage of "crater valleys," with 

 a general north and soutli axis. There are in all about ten cases of this kind on this 

 field, but several of them are not well disclosed by this illumination. 



