2G0 REPORT — 18GG. 



seem that its appearance or visibility is rare, being seen, as many other 

 objects are, only under particular angles of incidence and visual ray. Mr. 

 Knott examined the locality on the 23rd and 24th of February, 1866. He 

 does not mention it in his record, but says that '• Mr. Freeman's description 

 of this region tallies better with my own seeings than that of Mr, Webb."' 



It is not unlikely that the S.E. rim of Lohrmann's X (IV A'' ^) may possess 

 such a configuration as sometimes to throw the furrow out of sight. This 

 might be produced by the interior slope being presented to the eye nearly in 

 a vertical line. It clearl)- appears that this object may be placed amongst the 

 most delicate and fugitive of the lunar features. 

 f21. A small crater east of IV A^^. 

 This crater appears on the photograph as elliptical ? The longer axis, 

 E.-W., 4"-76 ; the shorter, N.-S., 2"-S5 ; mag. 0-23. It may be regarded 

 as a craterlet. Lohrmann gives two here, none on the W. 

 t22. A craterlet west of IV A^^ 2"-3S, mag. 0-16. 

 Mr. Freeman mentioned these craterlcts to me in a letter bearing date 1865, 

 January 21. On the 22nd of February, 1866, at HartweU, I recorded an 

 observation of them, and remarked that B. & M. gave only the east crater. 

 I, however, find in theii- map, close to the west border of IV A^^, a very 

 small crater, and if the two be intended by B. & M. for the craters seen by 

 Mr. Freemau and by me, the position of one, if not both, requires to be more 

 accurately determined. They are given on tlie map as they align in the 

 photograph. B. & M.'s craters lie S.E. and N.W. Mr. Freeman and I give 

 them as seen in the telescope, east and west. 1867, March 15, seen as on map. 

 23. The highest (?) point of the west border of Ptolemteus. 

 Well shown by Lohrmann both in his map and Section I., but indifferently 

 by B. k, M. The mountain presents a fine, bold and steep front W.N.W. to 

 the high land situated in the angle between Albategnius and Ptolemseus, 

 and extends N.N.E. to about the middle of IV A^^^. Length from the west 

 edge of IV A^ ^^ to the promontory opposite IV A^ " 13"-79. At its W.N.W. 

 foot is a valley, IV A^ '^, somewhat wide at first, but which gradually con- 

 tracts towards the N.X.E., and terminates at a point where the rill, IV A^ '^> 

 which furrows the slope of IVA^^^, also terminates. 



*24. A plain west of Herschel (III A^ ^), the S.AV. part. 

 There are several objects on this plain. See p. 279, IV A^ ''^*, &c. 

 **25. The formation between Ilalley IV A'''' and IV A^^. 

 This is a very individualized formation on the south part of Hipparchus, 

 measuring N.N.W.-S.S.E. from IV A'^^^-IV A^ ^2 j^jji^gi^.e^ 37"-09, and 

 W.S.W.-E.N.E. from IV A? -"^-XS A^ ^ inclusive, about 34". Its boundary 

 on the S.W. and south consists of a mountainous border, springing from the 

 mountain IV A^ ^^ on the east border of Halley, which forms the N.W. part 

 of the mountain-chain separating Albategnius from Ptolemteus, and of which 

 the mountain IV A^ '-<' is the highest point. The N.W. (IV A^ 27) ^^^1 j^jg. 

 boundaries appear to be depressed below the general surface, the N.W. some- 

 what in the nature of a riU with two elevations, IV A^^^, IV A^^", on the 

 S.E. side ; the N.E. has somewhat the appearance of a crater-row, two cra- 

 ters being very apparent, IV A^^" and IV A^'*''; in addition there are two 

 mountains, IV A^ ^^ and IV A^ "^^ At the east extremity of this formation 



