280 



REPORT 1866. 



IVA^ N.N.W.-S.S.E. No. 5.— This well-marked "line of fault" from 

 Tycho is continued across tlie area IV A* west of IV A* "^ and Ehaeticus. 



The careful study of the lines of upheaval and depression is particularly 

 recommended to lunar observers as full of promise. It is not at aU unlikely 

 that several of the " Rays from Tycho " will be found to possess the charac- 

 ter of lines of volcanic energy. It is an interesting fact that the two points 

 of upburst, IV A^ ^^ and IV Ay ^^, on the " ray from Tycho " crossing the area 

 IV A^ occur in localities where several lines of upheaval and depression in- 

 tersect each other. 



Concluding RemarJcs. 



We would again call attention to the Note on p. 239, to the effect that the 

 present Map is not intended to be perfect or complete ; and we are the more 

 anxious on this point, as various suggestions have been offered with the view 

 of rendering it more efficient, with which we most cordially agree. At pre- 

 sent the engraved portions of the Map are in outline, and will doubtless re- 

 quire considerable modification, as observers work at the subzones (see pp. 

 241, 242) which they may select. One suggestion, and a very important one, 

 is, " that as the craters on the moon's surface are the leading objects, catch- 

 ing the eye first, and giving points of reference to the region under obser- 

 vation, it would greatly facilitate the work of observers if the craters were 

 rendered more conspicuous in the engravings." The present imperfection of 

 our knowledge of " detail" interferes materially with adopting any conven- 

 tional mode of distinguishing one class of objects from another, further than 

 as explained on p. 240 ; but as the Maps are intended for working-purposes, and 

 are printed on paper that mil bear colouring, we would strongly recommend 

 that each observer should, before commencing his observations, tint with a 

 suitable colour the craters in his pair of subzones ; and if a few other conspi- 

 cuous objects, as mountains, were desirable as points of reference, they might 

 be tinted, but with a colour as much in contrast as possible. The portion of 

 Beer and Madler's map, referred to on p. 241, does not accompany this Re- 

 port. 



Appendix IV. 



Determination of the apparent Equator on De La Rue's Photograph, 1865, 



October 4* 9'^ 0"" 4'. 



