318 REPORT — 18G6. 



ward. It appears from ' Der Mond/ p. 375, that Boer and Miidlcr not only 

 saw one of the northern branches extending from Furnerius A about fifty-five 

 English miles, but also traced a southern and hrvjhtcr branch from this crater 

 extending as far as ninety English miles. They appear to be silent as to 

 any radiating streaks. Beer and Miidler also speak of one near Stevinus. I 

 have not yet been able to identify Beer and Miidler's positions. These " ray- 

 centres " are quite perceptible on the photograph, and the rays can be well 

 traced as far as the neighbourhood of Godin and jigrippa. The rays from 

 the easternmost centre bend round, and form branches of parabolic curves. 

 In areas III A^, IV A^, and IN Ayi, there is a considerable parallelism be- 

 tvreen several of the mountain-ranges and valleys, and these are seen on the 

 photographs, taken when Copernicus is near the terminator, gradually to fall 

 into the curves formed by the rays from the east centre. The valleys and 

 mountain-ranges are particvilarly specified in Appendix III. 



The occurrence of" light-centres," hitherto, I believe, unnoticed*, is another 

 feature of much interest. There are in the mountainous district before men- 

 tioned, between the Sinus Mcdil -AnAMare TranquiJlitaiis, four such centres. 

 They appear to be subordinate to ray-centres, are generally in immediate 

 connexion with craters, the interiors of which are very bright, and the light 

 spreads more or less regularly on all sides of them, as if the surface around 

 them consisted of strongly reflective materials. The north border of the 

 crater and light- centre IV A'' •^, which is very deep, is cracl-ed, and the crack 

 appears to penetrate the depth of the crater. This crack forms the south 

 part of the rill Xo. 362 of Schmidt's Catalogue, and is connected with a 

 "fault" which extends as far as and dislocates the west border of Rha^ticus 

 in the neighbourhood of the equator. If the crack, rill, and fault ori- 

 ginated at an epoch when IV A'' ^ was in a state of activity, the con- 

 vulsion of the interior must have been considerable, IV A'' " being about 7° 

 south of the equator, although nothing in comparison with that which 

 produced the bands issuing from Tycho and the two ray-centres in the south- 

 west. 



* During the passage of these sheets tlirongli the press, the Kev. T. AY. Wobb called 

 my attention to Beer and Miidler's remarks on the crater "Euclides," as showing that it 

 belongs to the class of " light-centres." Mr. Webb has kindly favoured lue with a trans- 

 lation, and Beer and Miidler's observations arc so much to the point that I gladly insert 

 them. For the original consult ' Der Mond,' p. 313. 



" Euclides especially distinguishes itself among the liy Id-surrounded (which are by no 

 means to be confounded with the radiating) craters. It is encompassed by a very bright 

 lumuious area, rather triangular than circular, brightest at its foot, but losmg itself in- 

 definitely on eveiy side. It may be perceived as far as Iv and £, aud consequently about 

 6 miles (27'6 miles English) away to the north. The whole lucid spot is quite flat and 

 hes in tlio level of the Mare, witli the exception of some vei-y inconspicuous hills that are 

 of no importance iii comparison with the wall of Euclides. 



" This altogether peculiar icliitish nimbus sliows itself only near a few craters of the 

 moon's surface, of which not one has more than li mile (about 7 miles EngUsh) in dia- 

 meter, and they almost aU lie between T 30' and 46° of longitude, and between the 

 equator and 15° of latitude. The radiating ring mountains are coUectively much larger, 

 do not show their gi-eatest brightness immediately at the foot, and extend this brightness 

 in long streaks. Craters with a brighter neighbourliood, which generally arises from sur- 

 rounding terraces, show themselves in abundance, but we may soon convince otu-selves by 

 mere inspection that this has nothing in common with the here mentioned appearance. 

 The craters belonging to this class are collectively very deep, strictly circular, never less 

 than 1° bright, little differing in respective magnitude, and extremely obvious under every 

 iUummation. The luminosity near Mosting c is quite of another natui-e, and that near 

 Lichtenberg does not show itself on every side, is fainter, and light-red rather than 

 whitish." 



