PLATE III. 



AGE OF MOON 8 DAYS, 4 HOURS. SEPTEMBER 22, l8gO. LICK OBSERVATORY. 



In this plate the most noteworthy features are the maria of the western half of the visible 

 portion of the sphere. The rudely circular form of these fields is well shown, also the fact that 

 none of them extend to the margin or " limb " of the moon. The bright, slightly curved ridge 

 in the lower half of the picture facing the partly illuminated mare, the Mare Imbrium, is the 

 Apennines ; the large vulcanoid at its southern end is Eratosthenes. The larger pit in the ocean 

 opposite the center of the range is Archimedes ; the two craters next to the north are : the nearer, 

 Autolycus, and the farther and larger, Aristillus. The larger of the two dark pits near the north- 

 ern end of the Apennines is Eudoxus, the smaller Aristoteles. Southeast from these craters lie 

 the Alps, a group of bright peaks extending in a northeast and southwest direction. A faint 

 dark streak shows the position of the Alpine valley. The flat, irregular area north of the range 

 is the M. Frigoris. 



Close inspection of this plate will show that many of the vulcanoids have pits or cones on 

 their floors, and that these are very often in the center of these level spaces. 



The radiating bands or streaks are beginning to appear. 



In the Mare Imbrium, near the western end of the Alps, next north of Aristillus, is Cassini, 

 of which the encircling cone appears to have been partly melted down by the lava of the mare so 

 that it shows as a faint ridge with a distinct central crater. 



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