PLATE I. 



GENERAL VIEW OF MOON, AGE 6 DAYS. BY S. W. BURNHAM, LICK OBSERVATORY. 



Plates I to VIII (inclusive) show the surface of the moon in progressive stages of illumination. 

 Taken at the Lick Observatory. 



In plate I the moon appears nearly half full. The crater of Abulfeda is coming into illumina- 

 tion. The most noteworthy features are the maria, which are evidently darker than the general 

 surface. The lowest of these, the M. Serenitatis, is obscurely circular with rather definite margins. 

 In it, on the west or left-hand side, are some faint folds of its floor. Just outside of this sea, to 

 the west, is a rather large distinct crater (Plinius). Horizontally eastward (to the right) in the 

 midst of the sea is a smaller dark crater (Bessel). The same line continued about as far still east- 

 wardly shows in a faint white spot the position of the crater Linnd, which is supposed to have been 

 destroyed in 1866 (see p. 70). The mare on which Plinius stands is the M. Tranquiiitatis. 

 Next southwardly beyond Theophilus (Plate XV) is the M. Nectaris. On the southern (upper) 

 margin of this sea is the crater of Fracastorius of which the northern part of the rim has evidently 

 been melted down by the sea. This is perhaps the most conspicuous instance of this nature among 

 the several score that may be noted on the margins of the several maria. The northernmost of the 

 maria in this view near the lunar margin is the tolerably circular M. Crisium. South of it is the 

 irregularly shaped M. Foecunditatis, without distinct boundaries. 



The observer should note the considerable range of brightness in the field, also how the craters 

 and other features become fainter near the brightly illuminated margin. 



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