PLATE II. 



MOON 7 DAYS OLD. BY S. W. BURNHAM, LICK OBSERVATORY. 



This plate shows the moon one day older than the preceding view. By comparison with plate 

 III the effect of twenty-four hours' advance in the lunar day may be perceived. On the " termin- 

 ator " or border of the advancing sunlight, a number of large vulcanoids may be seen in a tolerably 

 linear order. The most important of these, beginning with that nearest the equator and reckon- 

 ing southwardly, are Ptolomseus, Alphonsus, and Arzachel, then with an interval come Purbach, 

 Regiomontanus, and Walter. Traces of a like alignment are visible in other groups of lesser 

 vulcanoids. 



At this stage of the illumination some of the light streaks or rays begin to be visible, and may 

 be faintly traced on the left-hand side of the plate when the sun is highest. So, too, the bright 

 patches whence most of the streaks emanate, are beginning to become lucent. 



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