ox MAPPING THE SURFACE OF THE MOON. 265 



*75. A mountain south of IV A? ^^, at the S.E. end of the crater-rill 



IVA?S2 5"-23, mag. 0-31. 

 t76. A shght elevation, somewhat similar to a circular tableland, east of 

 the depression IV A^ ^ '^ 5"-23, mag. 0-3] . Not in Lohrmann. 

 **77. The slope of IV A? i** fronting the west, and south of IV A? ^, length 

 S.S.W.-N.N.E. 12"-84. Lohrmann, Sec. I. 16. 



78. The valley at the W.N.W. foot of lYA^-^, nearly parallel with 



IV A? ^-i, length, S.S.W.-N.N.E., 12"-84. 



79. A rill furrowing the jST.E. portion of the W.N.W. slope of IV A? 23 , 

 it communicates with the N.N.E. end of the valley IV A? '^, 

 length 6"-18; discovered July 21, 1866, by the author on Ruther- 

 ford's Photograph, and seen with the Royal Society's 4|-inch re- 

 fractor, power 230, on the 18th of August, 1866. 



80. A crater-form depression at the N.W. extremity of the N.E. 

 boundary of IV A? -^ 5"-23, mag. 0-31. Not in Lohrmann. 



81. A rill extending from the angle formed by the N.E. borders of 



IV A? ^f* and IV A? -^ to a point east of the cliff IV A? •*^ 16"-17. 



I do not find it in Schmidt's ' Catalogue of RiUs ; ' it was discovered, 



July 21, 1866, on Rutherford's Photograph. 

 This rill is in continuation of the line of cliffs that crosses Albategnius 

 andIVA^25_ r^^g elevations forming the JST.E. border of IVA^25 ^xaxe 

 apparently slightly heaved the line of cliffs, and probably produced the rill, 

 which runs but for a short distance. After crossing the central parts of 

 Hipparchus, the cliffs, which to the south present their faces to the W.S.W., 

 have them to the north, facing steeply the E.N.E. as well as "W.S.W. on the 

 borders of IV A* ^^ g^^j Rhaeticus. The whole line of cliffs is well marked, 

 extending from the east border of Albategnius to a point N".E. of Agrippa. 



82. A crater-rill on the N.E. waU of Albategnius 16"-17. It is probably 



No. 354 of Schmidt's ' Catalogue of Rills.' If so, it was discovered 

 by him on the 17th of August, 1843. It is in the same line with 

 IV A^ G7^ jjjj(j jjjQg^ probably the two formed one continuous crater- 

 rill at an earlier epoch than that of the protrusion of the line of 

 cliffs crossing IV A? ^5 ^nd Hipparchus, at which period the crater- 

 rill was separated into the two portions, IV A?"'' and IV A?^ ^2. 

 The earlier discovery of this rill, combined with the brightness and steep- 

 ness of IV A^^^, which Schmidt did not discover until February 3, 1865, 

 appears to point to a probable brightening and raising of IV A? "'' within the 



twenty-two years, otherwise the oversight of IV A? ^^ by Schmidt in 1843 is 

 remarkable. 



83. A valley parallel with IV A? '^^, but a httle more than half ita 



length. Length, S.S.W. to N.N.E., 8"-08. 



84. A vaUey in the west border of Ptolemajus opening out to the plain 

 between the mountains IV A^''' and IV? '", and running with a 

 gradual ascent between IV A ?^ 23 and IV A? ^•', to the high laud 

 bounded by the crater-rill IV A? ^3 to IV A? ^^ ; length about 1 6"-0. 



85. A valley between the two high mountains IVA?*" and IV A? 37 



length 64"-67. ' 



