ON MAPPING THE SURFACE OF THE MOON. 



275 



line of fault appears to be connected with Tycho. It does not appear at pre- 

 sent that W.N.W.-E.S.E. No. 2 is connected with any centre or point of 

 outbreak, unless it may be with lY AJi^, of which we may have to say more in 

 treating of that area. Another disturbed area occurs on IV A." between the 

 lines W.N.W.-E.S.E. No. 2, N.W.-S.E. No. 1 ; it is bounded on the west by 

 the line S. by W.-N. by E. No. 4. The lines of disturbance at right angles 

 to W.N.W.-E.S.E. are the most numerous, nearly 30 per cent, of the whole 

 on the two areas, equal to 17688-35 square miles Enghsh ; and there is some 

 reason to believe, as mentioned under IV A^^'', that the whole set maybe in 

 connexion with the easternmost of the ray-centres in the S.W. portion of the 

 moon, but a more extensive examination is necessary before this can be de- 

 cided. Arranging the whole of the directions according to a percentage scale, 

 we have as under : — 



The following Table exhibits the proportion in each area :- 



Area IV A* = 8877-925 square miles English. 

 Area IV A? = 8810-425 square miles English. 



It is worthy of remark that the directions giving the greatest numbers are 

 at right angles to each other. That which is evidently the main line of 

 fault, extending both N.N.W. and S.S.E. beyond the areas IV A* and IV A? 

 is accompanied with the next greatest number of parallel lines of upheaval 

 and depression, but confined to the eastward of the main Line of fault, while 

 in the other directions the numbers are few. 



The point between IV A? 69, ly A^ ^0^ jy ^^ 36^ ^nd IV A^ ^4 appears to be 

 a centre of disturbance, or point of upburst. There is one of a secondary 



character at IV A^ ^^, which is also a point of intersection of lines of upheaval 

 and depression. 



t2 



