PLATE XXIV. 



ARISTOTELES, EUDOXUS, AND SURROUNDINGS. PHOTOGRAPHED BY RITCHEY, OCTOBER 



13, igOO, 2 HOURS 40 MINUTES A.M. EXPOSURE SECOND. SCALE, 



THREE-FOURTHS METER TO MOON'S DIAMETER. 



In this plate the large vulcanoid near the top of the lower third of the field, that which cuts 

 the ring of the smaller crater on the left of its wall, is Aristoteles ; the somewhat smaller structure 

 just above is Eudoxus ; that near the upper left-hand corner is Posidonius. On the right hand, at 

 the same level as Aristoteles, the great Alpine valley is partly seen, the illumination being too nearly 

 vertical to show it well. 



Among the noteworthy features exhibited by this plate the following are the most important : 



The wall of Aristoteles evidently has broken that of the small unnamed crater adjacent to it on 

 the west (left-hand) side. This shows that Aristoteles was in activity since the smaller vulcanoid 

 was formed. The inner slopes of the first-named crater abound in rude terraces. Its limited 

 floor bears numerous cones. 



South of Eudoxus is an extensive field of elevations known as the Caucasus Mountains. The 

 western portion of this field peculiarly abounds in cones and craterlets of about the same diameter 

 as these cones, suggesting that the two groups of structure are in origin in some way related. 

 Certain other good examples of these cones are exhibited in the lower part of the plate. 



To the west of Eudoxus is a great, irregular vulcanoid with a large crater (Burg) somewhat 

 excentrically placed on its floor. On this floor are some remarkable rills. 



The greater part of the upper third of the plate is occupied by the Mare Serenitatis. A por- 

 tion of its mountain-like ridges is well shown. 



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