ON MAPPING THE SURFACE OF THE MOON. 37 
TV A&84, the depression IV A®*, and the W. slope of the mountain-peak 
IV A*%, which appear best to answer to them. 
85: A craterlet in the S.W. angle of IV Af**; length N.W.-S.E. 3°54, 
breadth 3'-17, mag. 0:20. It is the tenth in order upon area IV A®, 
86. The depression containing IV A&74, [TV AF ®, and LV AF ®, 
87. The depression in which IV A#*! and IV A? ® are situated. 
88. The plain E. of the depression IVA*® and N. of the valley 
TV Af, the E. part of Lohrmann’s 58, See. I. 
89. A “fault” of a minor character, which is traceable along the W. 
wall of the depression IV Af *; it grazes the E. edge of the ring IV Af ®, 
passes along the N. part of the crest IV Af *!, through the valley IV A’ ®, 
to a point westward of IV A” §. 
90. A hillock on the plain IV Af? IV AY 3, 
91. A shallow depression on the plain ITV Af? IV AY’?. 
92. A mountain-range between 1V A” and IV A& 7, N. end. 
A large portion of this range lies in area IV A”; length of crest 4-01, 
breadth of base 8'°48. 
93. A low mountain N. of IV A % ; length of crest 9-79. 
94, A valley-like depression S. of [V A®®7; length 8'-48, breadth 4°01. 
_ 95. A “cleft” from the 8. angle of Horrox to the middle point of the E. 
border of ITV Af 19, 
This “cleft,” which is visible on Rutherford’s photogram, appears 
either to have broken through the S. border of Hurrow or to have originated 
there ; the almost rectilinear 8. W. part of the rim of Horrow ends abruptly at 
the point where the “cleft” cuts it. The cleft has not affected [LV A®!%, but 
reappears in the high land on its W. side, passes through the depression 
TV A877, and opens out beyond the mountain IV Af *, the S. end of which 
is thrust forward in the direction of the line of “cleft”? into the valley 
IV Af, and is traced still further between IV Af ®3 and IV Af, The 
objects above specified are among the faintest on the moon’s disk. If 
the surfaces E. and W. of the fault IV A” IV A®20 IV A*? were con- 
tinuous at the time of the production of the “ cleft,’ and the “ cleft,” 
when formed, cut through the rim of Horroaw, we might be able to infer that 
the date of Horrox was anterior to the dates of the “ cleft,” fault, and craters 
IV Af 19, TV Af 1, and that the period of upheaval of the high land forming 
the W. border of HWipparchus was posterior to the epoch of the production of the 
W. floor of Hipparchus. The character of TY Af 1%, combined with the 
absence of any trace of the “cleft”? upon the crater, strongly indicates the 
posteriority of [TV A 19; and this, taken in connexion with the probable recent 
date of the fault TV A"!! TV A820 TV A*7, tends to establish that the con- 
formation of the features in this part of the lunar surface is of more recent 
origin than the system of “rays” from Tycho. 
96(x). The western of two ridges on the interior W. slope of Horrow. 
97. The eastern of two ridges on the interior W. slope of Horrow. 
These ridges are inserted provisionally, having been observed but once. 
96 was seen very satisfactorily on 1868, May 1¢ 9» 45™ with the Crossley 
equatorial of 7-3 in. aperture. 
98. A cleft running from the N.E. border of IV Af" to the fault TV A” 
Ty Af 0 TV A*”, near IV Af 82, 
99. A craterlet at the S. extremity of the buttress in the semicrater 
TV A* *, discovered with the Crossley equatorial on May 2, 1868. It is the 
thirteenth in order on IVA, : 
