ON MAPPING- THE SURFACE OF THE MOON. 267 



8672 English feet, or 2643 metres for its altitude. It appears to 



be on the line of cliffs on which the crater-row IV A^ ^^ to IV A^ "^ 

 is situated. 

 99. The steep interior slope of the east rim of HaUey, the west foot of 

 the mountain IV A^ -^, is distinctly visible on the floor of HaUey as 

 a curve projecting inwards. 



100. A craterlet on the north border of IV A? ^8 i".q^ ^^„_ q.iq 



101. A furrow crossing IV A^ ^^, .,t the foot of the cliff IV A?38_ The 



foot of the cliff with further indications of the furrow is continued 

 past IV A" '^ to the west edge of IV A" '". It was discovered by 

 the aiithor, Nov. 2, 1866, on Rutherford's photograph. 



102. A light spot just east of the vaUey IV A^ ^^ 3"-8, mag. 0-21. 



The strip of sm-face east of the vaUoy appears as a "ray" from IV A^^^. 

 It is on this ray that IV A^ '"^ is situated. 



[103.] IV A''-**, a crater or depression on the west side of IV A^^^. It 

 needs fiu'thor and careful observation. See p. 279, IV A ^. 



Summary of Hills, Crater-rows, and VaUeys registered as above not in 

 Schmidt's printed Catalogue : — • 



S. to N. IVA^9"toIVA^^2_ Crater-row, discovered August 



18, 1866. 

 S. to N. IVA^''°\ Furrow discovered November 2, 1866. 

 S.S.W. to N.N.E. IV A^ ^2 to IV A^ ^*. Crater-row*. 

 W.S.W. to E.N.E. IV A? *^ to IV A^ ^^. Crater-row. 



N.W. to S.E. IV A^ "^3 to IV A^^^ Crater-row, discovered August 



18, 1866. 



N.W. to S.E. IV A^"^. EiU discovered July 21, 1866. 



N.N.W. to S.S.E. IVA^^'. EiU discovered July 21, 1866. 



N.N.W. to S.S.E. IVA^84_ Yaiiey. 



N.N.W. to S.S.E. IV A^ 8^ VaUey. 



Area IV A". Full-Moon Aspect. 



One of the most interesting features of this area under the full- moon as- 

 pect is the portion of a " ray from Tycho," which traverses it from N.N.W. 

 to S.S.E. , and is coincident with the surface west of lihasticus, and also west 

 of the depression IV A" ' O- The mountains IV A" "^ the cliff IV A* 1 ■*, and the 

 south-west extremity of the valley IV A«^^ are crossed by this ray as well as 

 the west boundary of IV A" '". As the ray passes east of Horrox and crosses 

 the floor of Hipparchus, it is intersected by a short ray from Horrox towards 

 E.S.E., which includes the depression IV A" ''. 



The depressed surface IVA*^' around the crater IV A"*, which is a 

 blight spot at the time of full moon, exhibits a variety of middle tints that 

 appear to be unconnected with any definite objects, as none are found corre- 

 sponding with them when IV A" ' ^ is near the terminator. 



* Inserted on the iiuthority of Lohrmann. 



