ON MAPPING THE SURFACE OF THE MOON. 31: 
This “fault” is the westernmost of three that are nearly parallel and equi- 
distant, viz. [V Af #2, TV A®*l, and IV A% 20. These agree more or less in the 
steeper escarpments of the mountains found on them facing the E.8.E., their 
general direction being 8.8.W.—-N.N.E. Of the three, the fault IV A” ll 
Ly Af 20 TV A*” (see letterpress, areas IV A*, IV AS, p. 19, and Report 
Brit. Assoc. 1866, p. 255) is the longest and most distinctly marked as well as 
the easternmost. It is situated on the W. border of Hipparchus, and sepa- 
rates an elevated from a depressed tract of surface. If the parallelism of these 
faults points to a contemporaneity of origin, may we not recognize here the 
simultaneous operation of the upheaving force over a comparatively large 
area? It may be remarked, in connexion with this suggestion, that the two 
mountain-ranges forming the 8.8.W. and N.N.E. boundaries of the depressed 
portion E.S8.E. of the main fault IV A”! TV A*?o TV A“? have their steep 
escarpments towards depressed surfaces, 
With regard to the comparative ages of these faults, we have already sug- 
gested (letterpress, areas LV A*, IV AS p. 20, and Report Brit. Assoc. 1866, 
p. 256) that the fault IV A”"™ IV A#20 TV A*” is more recent than the 
“ray from Tycho” which it intersects; this suggestion is founded upon the 
fact that the “fault” is continuous throughout, but the “ray” is interrupted 
at the point of intersection. 
*43(x). A somewhat low mountain-range between IV A? 1° and IVAF 44, 
**44(x), A mountain-range §.E. of IV A* *%, situated on the line of cir- 
cumyallation around [TV A&? IV A’3, 
The short mountain-ranges [VY Af 4, TV Af 1, TY Af 43, and TV Af #4, with 
the crater IV A* ? and the intervening depressions, nearly form a radius from 
the centre to the circumference of the supposed ancient walled plain in which 
LY Af? IV A’* is situated. There are but few irregularities on the remaining 
portion of the plain. Itis probable these mountains are posterior in date to 
the plain. 
45(x), The crateriform depression between IV Af 1° and ITV Af 48, 
46, The valley between IV Af # and IV Af #4, 
_ This valley can be traced in a serpentine direction from between IV A* 43 and 
IV A* #4, past the W. end of [V A**, which slopes towards it, also past IV A® 7, 
which slopes towards the fault [IV A* *, through which IV Af 46 passes. 
**47(x). A mountain-peak on the W. border of Hipparchus, N.N.E. of 
TY A®%8. It is also on the fault IV A"! [TV Af 20 TV At? 
48, A wide opening or inlet in the mountain-border of Hi ipparchus, between 
the two mountain-peaks TV Af 38 and IV A®& 47, 
*#49. A depression W. of [TV Af", and between it and ITV Af*4, It is 
situated on the line of “circumyallation” around TVA 2p EAS: 
50, A shallow depression or crater on the S.W. border of IV Af}, 
diameter 8':02, mag. 0°47, which includes a rela of the depres- 
sion northwards (see TV AP 59 
51. A fault parallel with and between IV Ae”? and IV Af *0, 
This fault is the shortest of the three nearly parallel (see IV A* #2). It 
extends northward as far as the smooth surface on which Triesnecker is 
situated, and passes between LY A* 9 and LV Af ®2, along the W. border of 
IY Af** and the low ridge [LV A®7", towards the crater ITV A* ©, where it 
meets the line of fault TV A” LV AF 63, 
**52, A mountain-range forming the E.N.E. border of TV A®4, and part 
of the second wall of Aheticus on the west. It is 62 of Lohrmann’s 
See. I. 
*53(x). A semicrater on the “fault” TV A**1,S.8.E. of IV AS", Length 
