ON MAPPING THE SURFACE OF THE MOON. 11 



E'tpparchus, IV A" ^i, and the Sinus Medii, tend to invest them with peculiar 

 interest. The apparent cutting away of the higher ground forming the E. 

 slope of Hind, the projection beyond the general line of cliffs of the N.E. 

 border of Ilallei/, the indentations of the cliffs N.W. of HaUet/ by the ravines 

 scoring the E. slope of Hind, the general integrity of the cliffs S.E. of Halley, 

 and the absence of similar indentations (these cliffs being cat through in one 

 instance by a fault and in another scored by an apparent lava-channel) are 

 phenomena which do not generally characterize wailed plains. It is extremely 

 difficidt in the present state of our knowledge even to conjecture the kind of 

 agencies which have operated in the production of a line of cliffs analogous in 

 many respects to a terrestrial coast-line. One thing, however, appears to be 

 certain, viz. the anterior existence of the E. slope of Hind as regards both 

 Hdlley and the line of cliffs, while the fault and lava-channel on the S.E. are 

 apparently more recent than the cliffs in which they occur." 



" Hind is situated just W. of the fault IV A" 23, IV A^ «3^ and occupies the 

 highest point of the mountain-range IV A"" ^. The slopes around it are of 

 very different characters. On the S.E., E., and N.E. the exterior slope is 

 grooved or farrowed with well-marked radiating valleys, while on the S.W. 

 and N. the slope is uninterrupted and destitute of any radiating markings. 

 The more recent production of Hind, as compared with the fault on the E., is 

 indicated by the vaUeys on its flank cutting through the fault. The posteri- 

 ority of the formation of HalUy, as well as the prodiiction of the depression 

 IV A"" 21 and the low floor of Hipparclius, is strongly suggested by the land 

 on which the grooved valleys occur being penetrated by Halley on the one 

 hand, and abruptly terminated on the other by the depression IV A'' 21 and 

 the valley IV A" " on the S.E., and the chff IV A" i" forming the S.W. 

 border of Hipparchus on the jST.E. The remarkable smoothness of the floor of 

 Hipparchus in close proximity- with the cliffs is very significant." 



" The slope of Hind on the S.E., E., and N.E., with its valley-like furrows 

 and interrupted continuity by Halley, and the cliffs on the S.W. of Hippar- 

 chus before mentioned, may be advantageously compared with the crater 

 Aristillus on the Palus Nehularum, which to all appearance now exists in its 

 primeval state surrounded by its furrowed flanks, extending far on the 

 surfaces both of the Palus Nehularum and the Palus Putredinis. Only a 

 small portion of the flank of Hind remains, the outer portions having been 

 cut off by the more recent formations. It is not a little remarkable that the 

 cliff IV A'' i*' should be so distinct and precipitous in the neighbourhood of a 

 crater partly surrounded by the remnant of a furrowed slope ; and it is 

 difficult to conceive with such phenomena, that ejecta from a volcano such as 

 Hind appears to be, should extend no further than so precipitous a cliff as the 

 S.W. border of Hipparchus. The order of production appears to be as 

 follows : — the fault on the ray from Tycho, Hind, Hcdley. It is probable 

 that the production of the floor of Hipparchus occui'red at a stiU later epoch. 

 * * * The highest portion of the region in which Hind and Hcdley have 

 been opened bears some resemblance to the granitic plateau of central 

 France." 



" A very strong indication of the protrusion of Hcdley, subsequent to the 

 formation of the valley IV A^ 27, ly ^"j 17, and IV A*^ ^^, sui^posing the throe 

 portions were once connected, is afforded by the valley being completely 

 blocked on the JST.N.E. and S.S.W. by the E.S.E. rim of Hcdley. Mr. Ingall, 

 on June 26, 1866, pointed out to me the connexion of the valleys N.N.E. and 

 S.S.W. of Hcdley. At first sight this connexion might appear to be in 

 direction only. The valley IV Ai 27 ig certainly closed, as appears on the 



