ON MAPPING THE SURFACE OF THE MOON. 277 



plain W. Sec. I. (IV A"^, IV A^24^ ^jj-j^ g^ pj^^-^ ^^^^ ^^ Hipparchus. He 

 gives four openings (valleys) in the mountainous border of this plain, viz. 88, 

 89, and 90 of Sec. I., and another, which do not by any means appear pro- 

 minently in the photograph. 



59. Lohrmann gives this as the N.E. extremity of a long mountain-range 

 parallel with IV A* *^. 



61. Lohrmann gives a short low mountain-range which lies in the direc- 

 tion of this ray ; or it may be IV A* ^^. 



72. This " Fault," which under a suitable illumination is quite apparent, 

 is not indicated by Lohrmann, neither are the marked dislocations of the 

 border of Rhaeticus shown. 



75. The north portion of this valley, with apparently a low mountain- 

 range separating it from IV A* ''^, is shown by Lohrmann in Sec. I. 25. The 



valley IV A" ^^ as it enters IV A" ^^ has a darker tint in Lohrmann. 

 77. Lohrmann shows a plain here. 



79, 81. Are these the two craterlets which Lohrmann places at the entrance 

 of his vaUey, Sec. I. 87 ? 



80. Lohrmann mentions (p. 55) and delineates in this neighbourhood (pro- 

 bably the lower part of the slope of IV A* ^^) a valley, 87, Sect. I., 7 German 

 miles (.32-2 English miles) in length. This valley, with the individuahty 

 ascribed to it by Lohrmann, has not arrested my attention. I am neverthe- 

 less disposed to regard it as running between IV A"'''' and IV A* ^^. Lohr- 

 mann also mentions and shows two craterlets at its entrance. 



The following objects occur in Lohrmann's Section I., 15, 30, 68, 69, 70. 

 The following objects are not found in Lohrmann's Section I., 23, 38, 39, 

 40, 41, 46, 57, 60, 64, 65, ? 66, 71, 73, 74, 82, 83, 84. 



IV A^. — 25. This formation is alluded to, although not individually de- 

 scribed, by Lohrmann under 28, Sec. I., p. 44. The N.E. boundary is 

 exceedingly iU figured by Lohrmann, and 34, with its two mountain-peaks, 

 IV A^^' and IVA^'^'', is placed too far to the east. The valley IV A^^' 

 between IV A^^' and IV A^^' is blocked on the S.S.E. by Lohrmann. 



27. This vaUey is well shown by Lohrmann. In it, just JST.W. of his 

 mountain (IV A^^*^, IV A^^' shown as one), he has placed a craterlet, which 

 I have not found, nor am I aware that it is mentioned in his text. 



31. This mountain is sho-vyn in Sec. I. of Lohrmann, but the semi-crater 

 jY^?S8 jg absent. 



32. This mountain appears to be the N.E. spur of Lohrmann's 20, Sec. I., 

 the south part of which he places in the position of Schmidt,'s crater-rill 355. 

 I have not detected his N.W. spur, unless it be I V A^ ^ ' , which is a difficult 

 object. Lohrmann gives four craterlets on the east side of the N.E. spur. 

 I have seen three of them, viz. IV A^^O, IV A^^^ and IV A^^^^ 



33. 68. Both given by Lohrmann on Sec. I, IV A^^^ between his 48 and 

 20, and IV A? ^** on his 20. 



40. It is uncertain if Lohrmann has this craterlet ; he indicates a very 

 small depression of a similar nature not far from its locality. 



42, 43. Both these craterlets are given by Lohrmann on his mountain 19, 

 Sec. I. I have not yet met with this mountain. 



47. Lohrmann shows IV A^ *^ as connected with a range running towards 



