200 The Moon. 



that Alhazen was no longer to be found under any form, and 

 that the region seemed quite different ; nor did B. and M. 

 come to any other conclusion. They could discover no ring- 

 shaped mountain there — on the contrary, an abundance of 

 partly isolated, partly connected hills and mountains, and long, 

 dark, curved valleys and bays ; so, knowing the " great uncer- 

 tainty "* of Schrotcr's drawings, they fixed upon a crater con- 

 siderably further S. to bear the name, as it seemed to corres- 

 pond best with Schroter\s object. On the other hand, Pastorff 

 and Harding stated, in the Jahrbuch for 1827, that they could 

 always see Alhazen; and Kohler, under the year 1828, asserts that 

 it has not disappeared, but is very variable in aspect ; and he has 

 given several figures showing that it corresponds with B. and 

 M.'s Alhazen a, the loftiest mountain in the region, 7700 

 feet above the valley to the W. On the E. side of this height/ 

 between it and some low ridges, lies a deep hollow, with open- 

 ings to the " Mare," the colour of which varies with its illu- 

 mination, while the mountain itself might, from its shape, 

 sometimes take the aspect of a ring. And with this B. and 

 M. seem satisfied, notwithstanding their having changed the 

 name. At the commencement of 1862, Birt recovered this 

 spot, exactly in the position given by Schroter, and has 

 described it in detail as a deep valley between two mountain 

 ranges, of which the W. (a of B. and M.) is much the higher : 

 these arc quite separate at their S. eiid, but under many cir- 

 cumstances are barely distinguishable from the ring of a crater. 

 On the E. side of Alhazen, where Birt perceived one or two 

 in in ute craters, Gruithuisen fancied that certain rows of hillocks 

 might contain the habitations of Selenites ! and here, too, he 

 noticed rapid changes from bright to grey under .increasing 

 sunshine, which, being contrary to photometrical principles, 

 lie was disposed to refer to cultivation. Fanciful and absurd 

 as his speculations often are, we should not do right in syste- 

 matically rejecting his facts, some of which may be worthy of 

 further invest igation. 



* That there is occasional cause for this censuro need not bo denied, though 

 coarseness and rudeness of delineation would be a more appropriate characteristic. 

 But Still the old Hanoverian astronomer was far from always deserving the dis- 

 paraging remarks Of bil lUCCei (ore. For instance, they have brought it as a charge 

 against him that be drew the Mun- Oririum, "with all its environs," in a single 

 evening, and baa given it a bordering bo unlike the truth, that it is scarcely suili- 

 ( i in t lor its recognition (a bold and strange assertion), and is r|uite useless for the 

 identification of details ; and they a.-k how it is possiblo on such data to found 

 ideas n* to the existence of atmospheric ox volcanic changes. It would hardly bo 

 supposed that Sehroler's own expressions arc, that as a single evening is too short 

 for the examination, measurement, and delineation of such a region, and it would 



be wrong, and misleading, to piece together separate drawings taken under dif- 

 Eerent circumstances, his sketch is expressly confined to the interior level, and the 

 remarkable objects in the mountain border, but that the latter is merely laid down 

 in a general way. 



